Re: [MBZ] GP Infant Mortality ('91 300D 2.5T W124)
Jim Cathey wrote: need to put a light on the GPs and see how many seconds they're staying on when cold. We're getting mid 30'sF in the morning so I should get a lengthy glow. Around freezing you should be seeing something like 30 seconds of glow. If you don't, just wait that long anyway before starting. It ought to start a lot better. (You don't need a functioning light to get a good start, if you know how long you're supposed to wait.) Until temps get well below freezing, between 5-10 seconds is as long as the dash lamp should remain illuminated (if the relay is properly working). By zero deg.(F) that might extend out to 15-20 sec (although the later plugs optimized for afterglow heat MUCH faster and take only 10-15 sec to reach 1180 deg C vs 30 seconds for the older style plugs). It is usually desirable to allow the plugs to heat for an additional 10-15 sec AFTER the dash light extinguishes before once temps drop below freezing. The time constant that controls the duration of the dash lamp and time until power is turned off consists of a temperature sensitive resistor and a capacitor. When stored without being periodically energized, the capacitors deteriorate and after as little as a year they may fail and the temperature defined delay drops to almost nothing. Sometimes they can be revived by cycling them many times - and sometimes that doesn't work. Marshall -- Marshall Booth Ph.D. Ass't Prof. (ret.) Univ of Pittsburgh School of Medicine [EMAIL PROTECTED]
Re: [MBZ] GP Infant Mortality ('91 300D 2.5T W124)
For electronics I have a Fluke 189, for automotive stuff I keep a $3 harbor
freight multimeter in each car. I have rarely found any time I needed a more
expensive multimeter for car work.
A friend of mine has a $400 Snap On multimeter, which I refuse to use. It
has a little problem that when the battery is low it will read voltages
wrong. He replaced at least two alternators in a car due to the meter
reading the voltages low.
Fluke in my opinion is the best multimeters but you do not need that level
of performance for occasional use.
I also have a hall effect clamp on current meter, they are awesome and I use
mine a lot on just on cars but other items as well. For example checking a
water heater element over the weekend, it had power and with current meter I
just clamped on and verified that current was zero to know it was bad.
Otherwise I would had to cut power and measure resistance.
Trampas
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
On Behalf Of Jim Cathey
Sent: Monday, November 27, 2006 9:22 AM
To: Mercedes Discussion List
Subject: Re: [MBZ] GP Infant Mortality ('91 300D 2.5T W124)
> I saw some Flukes at Sears - for around ~$100. and some Simpson DMM's
> for
> a similiar price. I'll probably get one in that price range which I
> hope
> indicates a decent gauge.
It was a few years ago, but my (then-new) Fluke was more like $300.
I know they've come down since then! The true-RMS ones are superior,
and more expensive, but that may not matter to you.
> Anyway - I'll get a DMM that will read dc current as well as the more
> common readings -
I've never seen a commonly-available DMM that will measure more than
10A directly, including my Flukes. Some kind of adapter is needed to
go beyond that. The cool thing, of course, is the clamp-on hall-effect
current probe.
-- Jim
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Re: [MBZ] GP Infant Mortality ('91 300D 2.5T W124)
BTW, my GP system will work easily with your suggestion - I can unplug the wiring harness that goes to the individual GPs from the relay - it'll be easy to put the ammeter between the wire to each GP and the battery + side. Even easier is to use the screw that mounts the 80A fuse. That's hot all the time, and is right next to the plug. -- Jim
Re: [MBZ] GP Infant Mortality ('91 300D 2.5T W124)
Thanks Phillip! What a great solution. Jim C suggested a solution using
old GP parts but I didnt have them - this is something I can pick up for
small $'s and I understand exactly how to use it from your description.
BTW, my GP system will work easily with your suggestion - I can unplug the
wiring harness that goes to the individual GPs from the relay - it'll be
easy to put the ammeter between the wire to each GP and the battery + side.
Thanks again!
Larry T (67 MGB, 74 911, 78 240D, 91 300D)
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- Original Message -
From: "Fmiser" <[EMAIL PROTECTED]>
To: "Mercedes Discussion List"
Sent: Sunday, November 26, 2006 9:51 PM
Subject: Re: [MBZ] GP Infant Mortality ('91 300D 2.5T W124)
rumor has it that LarryT wrote:
BTW, I searched for a DMM that reads dc
current to 30a or so and no one had them. I'll order one though.
DMM can be hard to read the slope, or change over time.
The current draw starts high, then drops back a bit as the plug warms
up.
My favorite way to test them is with an old
add-a-gauge-under-the-dash-style ammeter. I had a +- 40A in my parts
box.
On a OM616 or OM617 with parallel plugs, I unplug the glow plugs from
the relay. This seperates the plugs - they now each have there own
wire. I then connect the ammeter between batter positive and each of
the glowplug contacts in the connector. It's quick and easy to see if
they all act the same.
I don't know how this method will adapt to a newer engine, but the
meter should work the same. I know Summit Racing sells an ammeter by
itself. I believe AutoZone does too.
--Philip
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Re: [MBZ] GP Infant Mortality ('91 300D 2.5T W124)
I saw some Fluke's at Sears - for around ~$100. and some Simpson DMMs for
a similiar price. I'll probably get one in that price range which I hope
indicates a decent gauge. It's so frustrating to go into a store and find
they're sold out of the thing I want. It just boggles my mind that a store
would be sold out of a product - some sell out often and to me the easiest
thing is to keep enough stuff on the shelf so customers don't walk out empty
handed.
SOrry 'bout the rant.
Anyway - I'll get a DMM that will read dc current as well as the more
common readings -
Thanks again for everyone's help on troubleshooting my GP system- I'm
convinced something inside the relay is flakey and hopefully the dealer
won't give me a hardtime & exchange it without a fight.
Larry T (67 MGB, 74 911, 78 240D, 91 300D)
www.youroil.net for Oil Analysis and Weber Parts
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- Original Message -
From: "Jim Cathey" <[EMAIL PROTECTED]>
To: "Mercedes Discussion List"
Sent: Sunday, November 26, 2006 10:00 PM
Subject: Re: [MBZ] GP Infant Mortality ('91 300D 2.5T W124)
DMM can be hard to read the slope, or change over time.
A fast-reading DMM, especially with the analog bar graph
(like the Fluke 8x series) works fairly well for that.
Cheap DMM's might convert slower, they might be harder to use.
-- Jim
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Re: [MBZ] GP Infant Mortality ('91 300D 2.5T W124)
Jim Cathey wrote: > A fast-reading DMM, especially with the analog bar graph > (like the Fluke 8x series) works fairly well for that. > Cheap DMM's might convert slower, they might be harder to use. > Don't trust the accuracy of cheap DMMs, either. Mine reads about 10% low on the voltage scales, these days. I need to change the battery and see if that helps.
Re: [MBZ] GP Infant Mortality ('91 300D 2.5T W124)
DMM can be hard to read the slope, or change over time. A fast-reading DMM, especially with the analog bar graph (like the Fluke 8x series) works fairly well for that. Cheap DMM's might convert slower, they might be harder to use. -- Jim
Re: [MBZ] GP Infant Mortality ('91 300D 2.5T W124)
rumor has it that LarryT wrote: > BTW, I searched for a DMM that reads dc > current to 30a or so and no one had them. I'll order one though. DMM can be hard to read the slope, or change over time. The current draw starts high, then drops back a bit as the plug warms up. My favorite way to test them is with an old add-a-gauge-under-the-dash-style ammeter. I had a +- 40A in my parts box. On a OM616 or OM617 with parallel plugs, I unplug the glow plugs from the relay. This seperates the plugs - they now each have there own wire. I then connect the ammeter between batter positive and each of the glowplug contacts in the connector. It's quick and easy to see if they all act the same. I don't know how this method will adapt to a newer engine, but the meter should work the same. I know Summit Racing sells an ammeter by itself. I believe AutoZone does too. --Philip
Re: [MBZ] GP Infant Mortality ('91 300D 2.5T W124)
Jim Cathey wrote: need to put a light on the GPs and see how many seconds they're staying on when cold. We're getting mid 30'sF in the morning so I should get a lengthy glow. Around freezing you should be seeing something like 30 seconds of glow. If you don't, just wait that long anyway before starting. It ought to start a lot better. (You don't need a functioning light to get a good start, if you know how long you're supposed to wait.) Later glow plugs designed for afterstart glow function reach maximum temp (1180 deg C) after only 10-15 sec while the plugs used thru most of the '80s took 30 sec to get that hot and series plugs took a minute or so to get that hot. Marshall -- Marshall Booth Ph.D. Ass't Prof. (ret.) Univ of Pittsburgh School of Medicine [EMAIL PROTECTED]
Re: [MBZ] GP Infant Mortality ('91 300D 2.5T W124)
Thanks Jim,
Tomorrow I'll try to talk the MB dealer into replacing the relay. And the
real fun begins. ;-)
Larry T (67 MGB, 74 911, 78 240D, 91 300D)
www.youroil.net for Oil Analysis and Weber Parts
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- Original Message -
From: "Jim Cathey" <[EMAIL PROTECTED]>
To: "Mercedes Discussion List"
Sent: Sunday, November 26, 2006 6:33 PM
Subject: Re: [MBZ] GP Infant Mortality ('91 300D 2.5T W124)
gets to after x seconds. it maxs out at 20 seconds and 1750F and
while it
will maintain that temp if the GP stays on ot doesn't get any hotter.
It
just stays hot longer.
The extra heat goes into the engine. It's not wasted. Sounds
like your GP's are working fine, only the light timer is wonky.
-- Jim
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Re: [MBZ] GP Infant Mortality ('91 300D 2.5T W124)
gets to after x seconds. it maxs out at 20 seconds and 1750F and while it will maintain that temp if the GP stays on ot doesn't get any hotter. It just stays hot longer. The extra heat goes into the engine. It's not wasted. Sounds like your GP's are working fine, only the light timer is wonky. -- Jim
Re: [MBZ] GP Infant Mortality ('91 300D 2.5T W124)
Jim wrote:<
of glow. If you don't, just wait that long anyway >>
That's what we've *been* doing since I replaced the GPs and relay - but I
want the preglow relay & light to work properly. And it sounds like a new
relay will be needed to make that happen. I read the chart in the WSM
showing the various glow times needed and the curve showing the temp the GP
gets to after x seconds. it maxs out at 20 seconds and 1750F and while it
will maintain that temp if the GP stays on ot doesn't get any hotter. It
just stays hot longer.
It starts instantly - we count to 15 when it's cold and it always starts on
the 1st 1/2 revolution.
Even when it was around 15F it starts after 15 seconds of glowtime. Always
starts instantly.
Larry T (67 MGB, 74 911, 78 240D, 91 300D)
www.youroil.net for Oil Analysis and Weber Parts
Test Results http://members.rennlist.com/oil
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- Original Message -
From: "Jim Cathey" <[EMAIL PROTECTED]>
To: "Mercedes Discussion List"
Sent: Sunday, November 26, 2006 5:17 PM
Subject: Re: [MBZ] GP Infant Mortality ('91 300D 2.5T W124)
need to put a light on the GPs and see how many seconds they're
staying on
when cold. We're getting mid 30'sF in the morning so I should get a
lengthy
glow.
Around freezing you should be seeing something like 30 seconds
of glow. If you don't, just wait that long anyway before starting.
It ought to start a lot better. (You don't need a functioning light
to get a good start, if you know how long you're supposed to wait.)
-- Jim
___
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Re: [MBZ] GP Infant Mortality ('91 300D 2.5T W124)
need to put a light on the GPs and see how many seconds they're staying on when cold. We're getting mid 30'sF in the morning so I should get a lengthy glow. Around freezing you should be seeing something like 30 seconds of glow. If you don't, just wait that long anyway before starting. It ought to start a lot better. (You don't need a functioning light to get a good start, if you know how long you're supposed to wait.) -- Jim
Re: [MBZ] GP Infant Mortality ('91 300D 2.5T W124)
Jim wrote:<> should have said it feels like its running on 4 cylinders out of 5. Also -when I tested the GPs with my Bat Chgr I should have mentioned it has a gauge on it - it was pegged at 15 amps on each trial. Don't know how accurate the gauge is - the charger is 20 years old. So I was able to test GP dc current draw after all - sort of. But I guess with it pegged it's not telling me much. BTW, I searched for a DMM that reads dc current to 30a or so and no one had them. I'll order one though. Marshalls suggestion about the TSB comment to cycle the relay to try and revive it is worth a try unless MB agrees to replace it - it's only 4-5 weeks old after all. I'll try to keep the battery from dieing. Also, I need to put a light on the GPs and see how many seconds they're staying on when cold. We're getting mid 30'sF in the morning so I should get a lengthy glow. I have to go to the dealer anyway to get the correct intake man gasket - they gave me a 6 cyl one by mistake. BTW, the wiring harness is in great condition - the car has 115000 babied miles on it and everything I come across as I work my way thru maint. items looks like its been well cared for or original. Thanks for everyong help - Larry T (67 MGB, 74 911, 78 240D, 91 300D) www.youroil.net for Oil Analysis and Weber Parts Test Results http://members.rennlist.com/oil PORSCHE POSTERS! youroil.net Weber Carb Info http://members.rennlist.com/webercarbs Porsche Road Test http://members.rennlist.com/roadtest/ . - Original Message - From: "Jim Cathey" <[EMAIL PROTECTED]> To: "Mercedes Discussion List" Sent: Sunday, November 26, 2006 3:24 PM Subject: Re: [MBZ] GP Infant Mortality tested them by attaching each in turn to a Batt chgr and all glowed red hot at the tip within ~12 sec. from the chart in the book that's pretty good - of course, they're all only about 4 weeks old. That sounds good. A plug can still get hot yet draw out-of-spec current, possibly enough to PO the GP relay. But if all five acted exactly the same the chances of this are lessened. Ok, the relay was replaced 4 weeks ago also after it failed to light up the GPs one night when my wife wanted to come home. A new replay gets the GPs to light but the light goes out within 1 sec (about 1/5 sec) and it feels like only 4 GPs are preglowing. The light is hooked to a temperature-sensitive timer. The GP's are hooked to a _different_ timer. They have nothing to do with each other, except that both are started with the key. If all five GP's do not heat up, and stay heating for something like 90+ seconds before automatically cutting off, then the GP relay is defective. With good GP's, if the light does not obey the ambient temperature/time curve that's in the (some, anyway) manuals, then it is defective. I don't know what you mean about the 'feel' of 4 GP's. What do you think? Should I just button things up? If we have definitively diagnosed the relay, yes. Unless you want to dive into the relay's guts to try to repair it. Bad for warrantee issues, and you risk making things worse too. If you still have your old one, of course... There was a TSB about cycling a preglow relay that exhibited foreshortened intervals about 10-12 times in a row (turn on the glow plugs and allow them to remain on until the relay cut off - and repeat 10-12 times - will likley run the battery down, but MAY revive the relay and timing MAY return to normal). This TSB (early/mid '80s as I recall) referred to new and used preglow relays that exhibited short timing intervals after being stored and not used for months or years. This is SOP for reforming an electrolytic capacitor, since the days of vacuum tubes. It doesn't always work, of course, but is worth a try. To save your battery just unplug the GP harness. The timers should still do their cycling, which should do any possible reformation during that time. To _really_ reform a cap, you need to take it out of circuit. At that point, of course, you'd just replace it. -- Jim ___ http://www.okiebenz.com For new parts see official list sponsor: http://www.buymbparts.com/ For used parts email [EMAIL PROTECTED] To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.409 / Virus Database: 268.14.16/552 - Release Date: 11/26/2006
Re: [MBZ] GP Infant Mortality
tested them by attaching each in turn to a Batt chgr and all glowed red hot at the tip within ~12 sec. from the chart in the book that's pretty good - of course, they're all only about 4 weeks old. That sounds good. A plug can still get hot yet draw out-of-spec current, possibly enough to PO the GP relay. But if all five acted exactly the same the chances of this are lessened. Ok, the relay was replaced 4 weeks ago also after it failed to light up the GPs one night when my wife wanted to come home. A new replay gets the GPs to light but the light goes out within 1 sec (about 1/5 sec) and it feels like only 4 GPs are preglowing. The light is hooked to a temperature-sensitive timer. The GP's are hooked to a _different_ timer. They have nothing to do with each other, except that both are started with the key. If all five GP's do not heat up, and stay heating for something like 90+ seconds before automatically cutting off, then the GP relay is defective. With good GP's, if the light does not obey the ambient temperature/time curve that's in the (some, anyway) manuals, then it is defective. I don't know what you mean about the 'feel' of 4 GP's. What do you think? Should I just button things up? If we have definitively diagnosed the relay, yes. Unless you want to dive into the relay's guts to try to repair it. Bad for warrantee issues, and you risk making things worse too. If you still have your old one, of course... There was a TSB about cycling a preglow relay that exhibited foreshortened intervals about 10-12 times in a row (turn on the glow plugs and allow them to remain on until the relay cut off - and repeat 10-12 times - will likley run the battery down, but MAY revive the relay and timing MAY return to normal). This TSB (early/mid '80s as I recall) referred to new and used preglow relays that exhibited short timing intervals after being stored and not used for months or years. This is SOP for reforming an electrolytic capacitor, since the days of vacuum tubes. It doesn't always work, of course, but is worth a try. To save your battery just unplug the GP harness. The timers should still do their cycling, which should do any possible reformation during that time. To _really_ reform a cap, you need to take it out of circuit. At that point, of course, you'd just replace it. -- Jim
Re: [MBZ] GP Infant Mortality
LarryT wrote: Hi JimC, Hope you're out there ;-) I've pulled the intake and removed the GPs - tested them by attaching each in turn to a Batt chgr and all glowed red hot at the tip within ~12 sec. from the chart in the book that's pretty good - of course, they're all only about 4 weeks old. I wrote:<< preglow light goes out within 1 sec. of turning the key) You replied --> That sounds like a problem internal to the GP relay. >> Ok, the relay was replaced 4 weeks ago also after it failed to light up the GPs one night when my wife wanted to come home. A new replay gets the GPs to light but the light goes out within 1 sec (about 1/5 sec) and it feels like only 4 GPs are preglowing. So, does this sound like enough testing to convince MB to replace the relay? I hate to buy another one (from Rusty this time) but if I have to so I'm sure it'll start and run properly I will. I tested the wiring between the relay and each GP - all have .4 ohms resistamce - don't know what else to test. What do you think? Should I just button things up? Glow plug relays that sit on the self (or in a car) for months or years without power being applied to them often have timing problems. The capacitors that determine the timing seem to deteriorate and that leads to very short intervals. You MIGHT get perfectly good starting by allowing the plugs to glow for 5-10 seconds AFTER the light goes off before starting, but that's not an ideal solution - that assums that power to the plugs continues for the proper period after the lamp goes off and the post start glow function timing is proper. There was a TSB about cycling a preglow relay that exhibited foreshortened intervals about 10-12 times in a row (turn on the glow plugs and allow them to remain on until the relay cut off - and repeat 10-12 times - will likley run the battery down, but MAY revive the relay and timing MAY return to normal). This TSB (early/mid '80s as I recall) referred to new and used preglow relays that exhibited short timing intervals after being stored and not used for montns or years. Marshall -- Marshall Booth Ph.D. Ass't Prof. (ret.) Univ of Pittsburgh School of Medicine [EMAIL PROTECTED]
Re: [MBZ] GP Infant Mortality
Hi JimC, Hope you're out there ;-) I've pulled the intake and removed the GPs - tested them by attaching each in turn to a Batt chgr and all glowed red hot at the tip within ~12 sec. from the chart in the book that's pretty good - of course, they're all only about 4 weeks old. I wrote:<< preglow light goes out within 1 sec. of turning the key) You replied --> That sounds like a problem internal to the GP relay. >> Ok, the relay was replaced 4 weeks ago also after it failed to light up the GPs one night when my wife wanted to come home. A new replay gets the GPs to light but the light goes out within 1 sec (about 1/5 sec) and it feels like only 4 GPs are preglowing. So, does this sound like enough testing to convince MB to replace the relay? I hate to buy another one (from Rusty this time) but if I have to so I'm sure it'll start and run properly I will. I tested the wiring between the relay and each GP - all have .4 ohms resistamce - don't know what else to test. What do you think? Should I just button things up? Larry T (67 MGB, 74 911, 78 240D, 91 300D) www.youroil.net for Oil Analysis and Weber Parts Test Results http://members.rennlist.com/oil PORSCHE POSTERS! youroil.net Weber Carb Info http://members.rennlist.com/webercarbs Porsche Road Test http://members.rennlist.com/roadtest/ . - Original Message - From: "Jim Cathey" <[EMAIL PROTECTED]> To: "Mercedes Discussion List" Sent: Wednesday, November 01, 2006 11:33 PM Subject: Re: [MBZ] GP Infant Mortality Got my 2 new GPs today so tomorow I'll try to find out what the problem is. To refresh memory - I have new GPs and new GP relay - preglow light goes out within 1 sec. of turning the key) That sounds like a problem internal to the GP relay. These things are likely NOS, not new-new, and the timing capacitor could have aged to death before you ever got it. I got my DMM out and set it to Resistance - using a new GP I touched the threads at the top and the threads that contact the cylinder head - got a reading of .3 - then I crossed the leads and the reading was .0 - is it OK that my DMM doesn't have a reading greater than .0? Yes, you just cross the leads to find out what its idea of zero is, and then subtract that from your reading. How do I tell if my DMM will measure current in the range you mentioned -- Was it exceedingly expensive? Then maybe. It's usually clearly written on the face somewhere, if it does current at all. I'm thinking I need at least a 30A max? But I think my DMM is good for 0A's - it's from Radio Shack -- Most DMM's have a 10A current scale, if they have anything at all. To measure more requires a shunt, rarely seen these days, or a relatively expensive clamp-on DC ammeter probe. Even my $300 Fluke only goes to 10A without the 400A external probe (another $200 IIRC). Attempts to measure more than 10A results in blowing its internal fuse, an item that costs more than an entire DMM from Harbor Freight. An old-fashioned charging gauge from the auto parts store could work, those are usually 60A over a half-scale, so are a bit too crude to get a good measurement off of. It would have detected my one bad one that had 2x normal current, however. -- Jim ___ http://www.okiebenz.com For new parts see official list sponsor: http://www.buymbparts.com/ For used parts email [EMAIL PROTECTED] To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.409 / Virus Database: 268.13.23/513 - Release Date: 11/2/2006
Re: [MBZ] GP Infant Mortality
I can handle a $20 ammeter. How will this be differnt from my 10A DMM? Simple, it'll measure 30A without burning out! So, this will tell me if the glow plug is getting hot? Nothing will tell you that, except maybe eyeballing one while it runs. But if it isn't drawing the proper amount of current you know it is not good. Would the test light on the GP tell me if the timer is staying on as long as it should? I'd have to do it when the engine is stone cold - not a problem lately - but when it's 30F-40F I should be getting 60+ seconds on the timer, right? Is it possible that the relay is coming on for ~1 second and slightly heating the GPs - enough to fire the engine. Since the engine is in *very* good condition it starts - altho it runs a little rough for 3-5 seconds when very cold - with the present GP (or relay) condition. Putting a test light or meter on a glow plug will tell you how long the timer is powering them, yes. Remember, there are _two_ timers in the GP relay: one for the plugs and one for the dash light. They're almost entirely unrelated to each other, and only the dash light timer is temperature-controlled. The other one just runs for about 1.5-2 minutes and times out. Unless the key is released from start, then it'll shut off then too. The light is just giving you its opinion on whether or not the GP's have heated for long enough. Nobody says you have to respect its opinion! BTW, I have a electrical tester for the battery & alt system - it clamps onto the battery terminals and depending on what I'm testing it will tell me if the alt or battery is bad. Don't recall what this is called. A voltmeter. Better ones measure AC ripple voltage looking for bad alternator diodes too. -- Jim
Re: [MBZ] GP Infant Mortality
Jim and Don wrote:<> I can handle a $20 ammeter. How will this be differnt from my 10A DMM? - if you could look at Radio Shack and give me a part number I'l now more what I'm trying to buy. I'm *really* electrically challenged if we go beyond continuity and test lights. I *can* understand it, but I work with it so seldom it takes a little *thinking* to get the concepts in my noggin'. So, this will tell me if the glow plug is getting hot? Or what? Would the test light on the GP tell me if the timer is staying on as long as it should? I'd have to do it when the engine is stone cold - not a problem lately - but when it's 30F-40F I should be getting 60+ seconds on the timer, right? Is it possible that the relay is coming on for ~1 second and slightly heating the GPs - enough to fire the engine. Since the engine is in *very* good condition it starts - altho it runs a little rough for 3-5 seconds when very cold - with the present GP (or relay) condition. Possible? BTW, I have a electrical tester for the battery & alt system - it clamps onto the battery terminals and depending on what I'm testing it will tell me if the alt or battery is bad. Don't recall what this is called. Thanks again for your patience - Larry T (67 MGB, 74 911, 78 240D, 91 300D) www.youroil.net for Oil Analysis and Weber Parts Test Results http://members.rennlist.com/oil PORSCHE POSTERS! youroil.net Weber Carb Info http://members.rennlist.com/webercarbs Porsche Road Test http://members.rennlist.com/roadtest/ . - Original Message - From: "OK Don" <[EMAIL PROTECTED]> To: "Mercedes Discussion List" Sent: Saturday, November 04, 2006 11:51 PM Subject: Re: [MBZ] GP Infant Mortality Yes - you can test to see if the glow plugs are getting 12v., but that doesn't mean they're getting hot. I like the suggestion to use a battery charger with an ammeter to read the current draw, or buy a $19.95 30-0-30 ammeter from a McParts house, connect a couple of 14 - 12 gauge wires, and put it between the wire and the glow plug - read the current in place. -- OK Don, KD5NRO Norman, OK "The Americans will always do the right thing... after they've exhausted all the alternatives." Sir Winston Churchill '90 300D, '87 300SDL, '81 240D, '78 450SLC, '97 Ply Grand Voyager ___ http://www.okiebenz.com For new parts see official list sponsor: http://www.buymbparts.com/ For used parts email [EMAIL PROTECTED] To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.409 / Virus Database: 268.13.27/517 - Release Date: 11/3/2006
Re: [MBZ] GP Infant Mortality
True - I'll look in the morning and see if I still have any series plugs. I don't have a car that uses them any more. On 11/4/06, Jim Cathey <[EMAIL PROTECTED]> wrote: I don't think that any methodology using a test light is going to tell you much more than the ohmmeter already did. For cheapness, little can beat using an old series GP as a current shunt, in conjunction with the voltmeter he already has. Doesn't anybody have one they can send him? I have a spare or two, but I also have a car that uses them. I'm planning to keep them in other words. -- Jim -- OK Don, KD5NRO Norman, OK "The Americans will always do the right thing... after they've exhausted all the alternatives." Sir Winston Churchill '90 300D, '87 300SDL, '81 240D, '78 450SLC, '97 Ply Grand Voyager
Re: [MBZ] GP Infant Mortality
I don't think that any methodology using a test light is going to tell you much more than the ohmmeter already did. For cheapness, little can beat using an old series GP as a current shunt, in conjunction with the voltmeter he already has. Doesn't anybody have one they can send him? I have a spare or two, but I also have a car that uses them. I'm planning to keep them in other words. -- Jim
Re: [MBZ] GP Infant Mortality
Yes - you can test to see if the glow plugs are getting 12v., but that doesn't mean they're getting hot. I like the suggestion to use a battery charger with an ammeter to read the current draw, or buy a $19.95 30-0-30 ammeter from a McParts house, connect a couple of 14 - 12 gauge wires, and put it between the wire and the glow plug - read the current in place. -- OK Don, KD5NRO Norman, OK "The Americans will always do the right thing... after they've exhausted all the alternatives." Sir Winston Churchill '90 300D, '87 300SDL, '81 240D, '78 450SLC, '97 Ply Grand Voyager
Re: [MBZ] GP Infant Mortality
Hi Jim, I was thinking again (always a bad sign) and thought I'd run this past you. To check the GP's I was thinking I could remove the intake manifold and then turn the key to Pre-Glow position. Then I can use my 12V test light to make sure each GP is getting power and maybe I'll even be able to tell how long the GPs stay lit. That should test the timer circuit as well as each wire from the relay to the GP - right? In lieu of the 12V test light I could use the DMM and see how much voltage each GP is getting. What value would I be looking for? 12V seems the obvious answer. Then, assuming all those tests look reasonable, I could remove the GPs and test them with my battery charger - Pos to the relay wire connection and neg to the threads that contact the block. The GPs should get *real* hot within 15 seconds. Would that test be enough to indicate a good GP? I also have a large starting battery charger but would probably use my small BC. I'm sure that big a$$ ammeter you mentioned is the preferred method but I probably wouldn't use it very often - and I'd rather not spend the $90. ;-) Would these tests narrow down the problem? Thanks again for your help -- Larry T (67 MGB, 74 911, 78 240D, 91 300D) www.youroil.net for Oil Analysis and Weber Parts Test Results http://members.rennlist.com/oil PORSCHE POSTERS! youroil.net Weber Carb Info http://members.rennlist.com/webercarbs Porsche Road Test http://members.rennlist.com/roadtest/ . - Original Message - From: "Jim Cathey" <[EMAIL PROTECTED]> To: "Mercedes Discussion List" Sent: Friday, November 03, 2006 10:13 AM Subject: Re: [MBZ] GP Infant Mortality clamp-on DC ammeter myself, because it's also good for measuring things like starter current, etc. They're not particularly cheap, but they can certainly be had for less than my Fluke cost me. This one, for example, is $90. http://www.electrical-contractor.net/The_Store/EX/MA200_220.htm The 400A range is nice for automotive work, because starters (usually) draw less than this. -- Jim ___ http://www.okiebenz.com For new parts see official list sponsor: http://www.buymbparts.com/ For used parts email [EMAIL PROTECTED] To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.409 / Virus Database: 268.13.25/515 - Release Date: 11/3/2006
Re: [MBZ] GP Infant Mortality
Thanks Jim - I'll study on this for a while - Larry T (67 MGB, 74 911, 78 240D, 91 300D) www.youroil.net for Oil Analysis and Weber Parts Test Results http://members.rennlist.com/oil PORSCHE POSTERS! youroil.net Weber Carb Info http://members.rennlist.com/webercarbs Porsche Road Test http://members.rennlist.com/roadtest/ . - Original Message - From: "Jim Cathey" <[EMAIL PROTECTED]> To: "Mercedes Discussion List" Sent: Friday, November 03, 2006 10:13 AM Subject: Re: [MBZ] GP Infant Mortality clamp-on DC ammeter myself, because it's also good for measuring things like starter current, etc. They're not particularly cheap, but they can certainly be had for less than my Fluke cost me. This one, for example, is $90. http://www.electrical-contractor.net/The_Store/EX/MA200_220.htm The 400A range is nice for automotive work, because starters (usually) draw less than this. -- Jim ___ http://www.okiebenz.com For new parts see official list sponsor: http://www.buymbparts.com/ For used parts email [EMAIL PROTECTED] To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.409 / Virus Database: 268.13.25/515 - Release Date: 11/3/2006
Re: [MBZ] GP Infant Mortality
Gentlemen, the way I test GPs is with a battery charger which has a 0 - 20 AMMETER by connecting the GP to the leads and watch the ammeter go to around 20A and as the GP heats the current slowly drops to around 15A and stays at 15A steady state. Now that is a good GP. Darrell Jim Cathey wrote: Did my test of the resistance of the wiring & GPs do any good at all? Yes, it appears that your test has cleared the GP's themselves of being completely dead. But there is still room for doubt given the borderline ability of most meters to give accurate readings in this range. Should I ty to get Mercedes to fork over a new relay? If I tell them I You could try, but were I they I'd want a little more proof. You need a hefty ammeter, or that series glow plug. I like the clamp-on DC ammeter myself, because it's also good for measuring things like starter current, etc. They're not particularly cheap, but they can certainly be had for less than my Fluke cost me. One of the 'toaster racks' from a series-GP MB would also work, with a voltmeter. All you're really doing is looking for imbalances among the GP's, but you need something capable of taking 20-30A of current without melting or dropping too much or too little voltage in series with the plug. (Untwisted wire coat hanger with the ends filed clean? It's a substantial length of iron [poor] wire, of smallish diameter. Just grasping at straws here.) I still have the old relay - and it's got a card filled with soldered joints holding lots of little things in line. If I test those for continuity will that help point to the part that's possibly bad - or has a bad solder joint? Unlikely to be of any success. Resoldering them, if you can actually solder well, may work wonders. It restored the one in my 190D to life. (Though it seems to be timing the light too long right now, I need to look into that sometime.) I may re-install the old relay to see how things act. Couldn't hurt, and could give you another data point. OK - back to the new relay and new GPs - it seems like either #1 is bad or the relay is bad - sound reasonable? Really it could be any of the GP's, though it is most sensitive to poor behavior on #1. Or the wiring to them. Unfortunately you really haven't completely ruled out anything yet. The next test is a current test of each plug, you need to figure out a way to do that. -- Jim ___ http://www.okiebenz.com For new parts see official list sponsor: http://www.buymbparts.com/ For used parts email [EMAIL PROTECTED] To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] GP Infant Mortality
clamp-on DC ammeter myself, because it's also good for measuring things like starter current, etc. They're not particularly cheap, but they can certainly be had for less than my Fluke cost me. This one, for example, is $90. http://www.electrical-contractor.net/The_Store/EX/MA200_220.htm The 400A range is nice for automotive work, because starters (usually) draw less than this. -- Jim
Re: [MBZ] GP Infant Mortality
Did my test of the resistance of the wiring & GPs do any good at all? Yes, it appears that your test has cleared the GP's themselves of being completely dead. But there is still room for doubt given the borderline ability of most meters to give accurate readings in this range. Should I ty to get Mercedes to fork over a new relay? If I tell them I You could try, but were I they I'd want a little more proof. You need a hefty ammeter, or that series glow plug. I like the clamp-on DC ammeter myself, because it's also good for measuring things like starter current, etc. They're not particularly cheap, but they can certainly be had for less than my Fluke cost me. One of the 'toaster racks' from a series-GP MB would also work, with a voltmeter. All you're really doing is looking for imbalances among the GP's, but you need something capable of taking 20-30A of current without melting or dropping too much or too little voltage in series with the plug. (Untwisted wire coat hanger with the ends filed clean? It's a substantial length of iron [poor] wire, of smallish diameter. Just grasping at straws here.) I still have the old relay - and it's got a card filled with soldered joints holding lots of little things in line. If I test those for continuity will that help point to the part that's possibly bad - or has a bad solder joint? Unlikely to be of any success. Resoldering them, if you can actually solder well, may work wonders. It restored the one in my 190D to life. (Though it seems to be timing the light too long right now, I need to look into that sometime.) I may re-install the old relay to see how things act. Couldn't hurt, and could give you another data point. OK - back to the new relay and new GPs - it seems like either #1 is bad or the relay is bad - sound reasonable? Really it could be any of the GP's, though it is most sensitive to poor behavior on #1. Or the wiring to them. Unfortunately you really haven't completely ruled out anything yet. The next test is a current test of each plug, you need to figure out a way to do that. -- Jim
Re: [MBZ] GP Infant Mortality
Hi Jim, I sincerely appreciate you taking the time to do the writeup below - but my limited knowledge of electrical stuff makes most of it meaningless. Did my test of the resistance of the wiring & GPs do any good at all? Should I ty to get Mercedes to fork over a new relay? If I tell them I believe it's bad because the resistance of the rest of the GP circuit says *that* part was good leaving the relay as the only part left as suspect - would they buy that? I know you cannot speak for the parts guys - just looking for some way to gauge my possible success ;-) I hate to keep bothering you about this -- but I'd like to have it working properly since my wife drives this one all the time. She has no trouble counting to 10-15 before cranking though. ;-) I still have the old relay - and it's got a card filled with soldered joints holding lots of little things in line. If I test those for continuity will that help point to the part that's possibly bad - or has a bad solder joint? I may re-install the old relay to see how things act. OK - back to the new relay and new GPs - it seems like either #1 is bad or the relay is bad - sound reasonable? Thanks again for all your time spent explaining this stuff to me - I'm not dumb, (it only seems that way) but my experience has been mechanical with electrical limited to getting lights working for the most part -- Larry T (67 MGB, 74 911, 78 240D, 91 300D) www.youroil.net for Oil Analysis and Weber Parts Test Results http://members.rennlist.com/oil PORSCHE POSTERS! youroil.net Weber Carb Info http://members.rennlist.com/webercarbs Porsche Road Test http://members.rennlist.com/roadtest/ . - Original Message - From: "Jim Cathey" <[EMAIL PROTECTED]> To: "Mercedes Discussion List" Sent: Friday, November 03, 2006 12:57 AM Subject: Re: [MBZ] GP Infant Mortality got a reading of .4 on all 5 - The nominal 0.6 ohm (cold, but not too cold) value of the new-style plugs is in the borderline area of being able to use a garden-variety ohmmeter to diagnose. Consider the lowly series plug of yore, that has a nominal (hot) resistance of 0.02 ohms, probably half that when cold. That's why you use a voltmeter in-circuit to diagnose those, there's hardly an ohmmeter alive that can give you that number meaningfully. But fed 50A of current and the nominal 1V dropped across it is well within the good range of a standard voltmeter. In effect you're using the remainder of that GP system as a dummy load for the DUT. No such luck on the parallel system, you need a hefty series (or clamp-on) DC ammeter to diagnose those, if the ohmmeter doesn't cut it. Another idea would be to keep around an old series GP for use as a shunt for measuring heavy current. It would drop 1-2V feeding a new-style GP. A little bit of calibration work with a known good plug or two and you'd have a cheap (and small) test harness for GP's. Just don't burn yourself! -- Jim ___ http://www.okiebenz.com For new parts see official list sponsor: http://www.buymbparts.com/ For used parts email [EMAIL PROTECTED] To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.409 / Virus Database: 268.13.23/513 - Release Date: 11/2/2006
Re: [MBZ] GP Infant Mortality
got a reading of .4 on all 5 - The nominal 0.6 ohm (cold, but not too cold) value of the new-style plugs is in the borderline area of being able to use a garden-variety ohmmeter to diagnose. Consider the lowly series plug of yore, that has a nominal (hot) resistance of 0.02 ohms, probably half that when cold. That's why you use a voltmeter in-circuit to diagnose those, there's hardly an ohmmeter alive that can give you that number meaningfully. But fed 50A of current and the nominal 1V dropped across it is well within the good range of a standard voltmeter. In effect you're using the remainder of that GP system as a dummy load for the DUT. No such luck on the parallel system, you need a hefty series (or clamp-on) DC ammeter to diagnose those, if the ohmmeter doesn't cut it. Another idea would be to keep around an old series GP for use as a shunt for measuring heavy current. It would drop 1-2V feeding a new-style GP. A little bit of calibration work with a known good plug or two and you'd have a cheap (and small) test harness for GP's. Just don't burn yourself! -- Jim
Re: [MBZ] GP Infant Mortality
I just checked the wiring and GPs by testing the resistance between the plug at the relay and the engine. I removed the plug and put the pos lead in the plug and the neg against the engine block - got a reading of .4 on all 5 - Does that mean my wiring *&* the GPs is good or do I have to remove the GPs? Sounds right. Also - assuming the wiring and GPs are good - I guess that means the relay is bad? Probably. But a current-check of the GP's would be definitive. Remember that the relay balances the current drawn by #1 against a ratio of the current drawn by the rest. If any plug draws the wrong amount of current, especially #1, the relay's light will not work correctly. That's its diagnostic channel back to you. -- Jim
Re: [MBZ] GP Infant Mortality
Cosider this: It starts instantly - after I count to 10 before firing it up - so it *is* pre-glowing the GPs. Else it would be hard to start. When it starts, it seems as though 1 cylinder is not firing until ~10 seconds after the engine starts - which makes me think it's a GP or the wiring - The _best_ check of the plugs, except for just swapping them out for new, is to get a hefty ammeter and jumper each one in turn to +12V (the fuse screw in the GP relay is handy) while monitoring the current draw. Starts out about 30A (each), dropping below 20A within a few seconds. The GP relay has _two_ timers in it. One to run the plugs, and one to run the light. Only the latter is temperature-sensitive. Only the latter is hooked to the GP-out circuitry. In a pinch you just count potatoes for a suitable time before starting, in effect pretending the light is working properly. If the Relay were at fault - especially the timer - wouldn;t it be hard to start (or not start at all) if the GPs were not pre-glowing? Yes indeed. One other observation - after the car starts while I'm keeping the revs at ~1000 maybe 45 seconds after it starts, I noticed the interior lights get brighter - I take this to mean the GPs have "turned-off". Sounds right. Normally they turn off as soon as the key is released from start, but the newer systems (and retrofits) have a post-start glow cycle that improves cold running, at the expense of GP life. -- Jim
Re: [MBZ] GP Infant Mortality
Jim wrote:<< That sounds like a problem internal to the GP relay. These things are likely NOS, not new-new, and the timing capacitor >> Hi Jim, Need your expertise one more time -- I just checked the wiring and GPs by testing the resistance between the plug at the relay and the engine. I removed the plug and put the pos lead in the plug and the neg against the engine block - got a reading of .4 on all 5 - Does that mean my wiring *&* the GPs is good or do I have to remove the GPs? Also - assuming the wiring and GPs are good - I guess that means the relay is bad? Thanks again for your help - and, changing the relay is gonna be a *whole* lot easier than changing the wires or GP's! ;-) (if that's what is indicated as being bad) Larry T (67 MGB, 74 911, 78 240D, 91 300D) www.youroil.net for Oil Analysis and Weber Parts Test Results http://members.rennlist.com/oil PORSCHE POSTERS! youroil.net Weber Carb Info http://members.rennlist.com/webercarbs Porsche Road Test http://members.rennlist.com/roadtest/ . - Original Message - From: "Jim Cathey" <[EMAIL PROTECTED]> To: "Mercedes Discussion List" Sent: Wednesday, November 01, 2006 11:33 PM Subject: Re: [MBZ] GP Infant Mortality Got my 2 new GPs today so tomorow I'll try to find out what the problem is. To refresh memory - I have new GPs and new GP relay - preglow light goes out within 1 sec. of turning the key) That sounds like a problem internal to the GP relay. These things are likely NOS, not new-new, and the timing capacitor could have aged to death before you ever got it. I got my DMM out and set it to Resistance - using a new GP I touched the threads at the top and the threads that contact the cylinder head - got a reading of .3 - then I crossed the leads and the reading was .0 - is it OK that my DMM doesn't have a reading greater than .0? Yes, you just cross the leads to find out what its idea of zero is, and then subtract that from your reading. How do I tell if my DMM will measure current in the range you mentioned -- Was it exceedingly expensive? Then maybe. It's usually clearly written on the face somewhere, if it does current at all. I'm thinking I need at least a 30A max? But I think my DMM is good for 0A's - it's from Radio Shack -- Most DMM's have a 10A current scale, if they have anything at all. To measure more requires a shunt, rarely seen these days, or a relatively expensive clamp-on DC ammeter probe. Even my $300 Fluke only goes to 10A without the 400A external probe (another $200 IIRC). Attempts to measure more than 10A results in blowing its internal fuse, an item that costs more than an entire DMM from Harbor Freight. An old-fashioned charging gauge from the auto parts store could work, those are usually 60A over a half-scale, so are a bit too crude to get a good measurement off of. It would have detected my one bad one that had 2x normal current, however. -- Jim ___ http://www.okiebenz.com For new parts see official list sponsor: http://www.buymbparts.com/ For used parts email [EMAIL PROTECTED] To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.409 / Virus Database: 268.13.23/513 - Release Date: 11/2/2006
Re: [MBZ] GP Infant Mortality
Jim wrote:<< That sounds like a problem internal to the GP relay. These things are likely NOS, not new-new, and the timing capacitor >> Hi Jim, I just checked the wiring and GPs by testing the resistance between the plug at the relay and the engine. I removed the plug and put the pos lead in the plug and the neg against the engine block - got a reading of .4 on all 5 - Does that mean my wiring *&* the GPs is good or do I have to remove the GPs? Also - assuming the wiring and GPs are good - I guess that means the relay is bad? Thanks again for your help - and, changing the relay is gonna be a *whole* lot easier than changing the wires or GP's! ;-) (if that's what is indicated as being bad) Larry T (67 MGB, 74 911, 78 240D, 91 300D) www.youroil.net for Oil Analysis and Weber Parts Test Results http://members.rennlist.com/oil PORSCHE POSTERS! youroil.net Weber Carb Info http://members.rennlist.com/webercarbs Porsche Road Test http://members.rennlist.com/roadtest/ . - Original Message - From: "Jim Cathey" <[EMAIL PROTECTED]> To: "Mercedes Discussion List" Sent: Wednesday, November 01, 2006 11:33 PM Subject: Re: [MBZ] GP Infant Mortality Got my 2 new GPs today so tomorow I'll try to find out what the problem is. To refresh memory - I have new GPs and new GP relay - preglow light goes out within 1 sec. of turning the key) That sounds like a problem internal to the GP relay. These things are likely NOS, not new-new, and the timing capacitor could have aged to death before you ever got it. I got my DMM out and set it to Resistance - using a new GP I touched the threads at the top and the threads that contact the cylinder head - got a reading of .3 - then I crossed the leads and the reading was .0 - is it OK that my DMM doesn't have a reading greater than .0? Yes, you just cross the leads to find out what its idea of zero is, and then subtract that from your reading. How do I tell if my DMM will measure current in the range you mentioned -- Was it exceedingly expensive? Then maybe. It's usually clearly written on the face somewhere, if it does current at all. I'm thinking I need at least a 30A max? But I think my DMM is good for 0A's - it's from Radio Shack -- Most DMM's have a 10A current scale, if they have anything at all. To measure more requires a shunt, rarely seen these days, or a relatively expensive clamp-on DC ammeter probe. Even my $300 Fluke only goes to 10A without the 400A external probe (another $200 IIRC). Attempts to measure more than 10A results in blowing its internal fuse, an item that costs more than an entire DMM from Harbor Freight. An old-fashioned charging gauge from the auto parts store could work, those are usually 60A over a half-scale, so are a bit too crude to get a good measurement off of. It would have detected my one bad one that had 2x normal current, however. -- Jim ___ http://www.okiebenz.com For new parts see official list sponsor: http://www.buymbparts.com/ For used parts email [EMAIL PROTECTED] To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.409 / Virus Database: 268.13.23/513 - Release Date: 11/2/2006
Re: [MBZ] GP Infant Mortality
you wrote:< goes out within 1 sec. of turning the key)> That sounds like a problem internal to the GP relay>> Jim, Cosider this: It starts instantly - after I count to 10 before firing it up - so it *is* pre-glowing the GPs. Else it would be hard to start. When it starts, it seems as though 1 cylinder is not firing until ~10 seconds after the engine starts - which makes me think it's a GP or the wiring - It this a good assumption? If the Relay were at fault - especially the timer - wouldn;t it be hard to start (or not start at all) if the GPs were not pre-glowing? One other observation - after the car starts while I'm keeping the revs at ~1000 maybe 45 seconds after it starts, I noticed the interior lights get brighter - I take this to mean the GPs have "turned-off". Is this likely? as always - TIA! Larry T (67 MGB, 74 911, 78 240D, 91 300D) www.youroil.net for Oil Analysis and Weber Parts Test Results http://members.rennlist.com/oil PORSCHE POSTERS! youroil.net Weber Carb Info http://members.rennlist.com/webercarbs Porsche Road Test http://members.rennlist.com/roadtest/ . - Original Message - From: "Jim Cathey" <[EMAIL PROTECTED]> To: "Mercedes Discussion List" Sent: Wednesday, November 01, 2006 11:33 PM Subject: Re: [MBZ] GP Infant Mortality Got my 2 new GPs today so tomorow I'll try to find out what the problem is. To refresh memory - I have new GPs and new GP relay - preglow light goes out within 1 sec. of turning the key) That sounds like a problem internal to the GP relay. These things are likely NOS, not new-new, and the timing capacitor could have aged to death before you ever got it. I got my DMM out and set it to Resistance - using a new GP I touched the threads at the top and the threads that contact the cylinder head - got a reading of .3 - then I crossed the leads and the reading was .0 - is it OK that my DMM doesn't have a reading greater than .0? Yes, you just cross the leads to find out what its idea of zero is, and then subtract that from your reading. How do I tell if my DMM will measure current in the range you mentioned -- Was it exceedingly expensive? Then maybe. It's usually clearly written on the face somewhere, if it does current at all. I'm thinking I need at least a 30A max? But I think my DMM is good for 0A's - it's from Radio Shack -- Most DMM's have a 10A current scale, if they have anything at all. To measure more requires a shunt, rarely seen these days, or a relatively expensive clamp-on DC ammeter probe. Even my $300 Fluke only goes to 10A without the 400A external probe (another $200 IIRC). Attempts to measure more than 10A results in blowing its internal fuse, an item that costs more than an entire DMM from Harbor Freight. An old-fashioned charging gauge from the auto parts store could work, those are usually 60A over a half-scale, so are a bit too crude to get a good measurement off of. It would have detected my one bad one that had 2x normal current, however. -- Jim ___ http://www.okiebenz.com For new parts see official list sponsor: http://www.buymbparts.com/ For used parts email [EMAIL PROTECTED] To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.409 / Virus Database: 268.13.23/513 - Release Date: 11/2/2006
Re: [MBZ] GP Infant Mortality
30-0-30 ammeter. On Wed, 01 Nov 2006 22:33:54 -0600, Jim Cathey <[EMAIL PROTECTED]> wrote: >> Got my 2 new GPs today so tomorow I'll try to find out what the >> problem is. >> To refresh memory - I have new GPs and new GP relay - preglow light >> goes out >> within 1 sec. of turning the key) > > That sounds like a problem internal to the GP relay. These things are > likely NOS, not new-new, and the timing capacitor could have aged to > death before you ever got it. > >> I got my DMM out and set it to >> Resistance - using a new GP I touched the threads at the top and the >> threads >> that contact the cylinder head - got a reading of .3 - then I crossed >> the >> leads and the reading was .0 - is it OK that my DMM doesn't have a >> reading >> greater than .0? > > Yes, you just cross the leads to find out what its idea of zero is, and > then subtract that from your reading. > >> How do I tell if my DMM will measure current in the range you >> mentioned -- > > Was it exceedingly expensive? Then maybe. It's usually clearly written > on the face somewhere, if it does current at all. > >> I'm thinking I need at least a 30A max? But I think my DMM is good for >> 0A's - it's from Radio Shack -- > > Most DMM's have a 10A current scale, if they have anything at all. > To measure more requires a shunt, rarely seen these days, or a > relatively expensive clamp-on DC ammeter probe. Even my $300 Fluke > only goes to 10A without the 400A external probe (another $200 IIRC). > Attempts to measure more than 10A results in blowing its internal > fuse, an item that costs more than an entire DMM from Harbor Freight. > > An old-fashioned charging gauge from the auto parts store could work, > those are usually 60A over a half-scale, so are a bit too crude to get > a good measurement off of. It would have detected my one bad one that > had 2x normal current, however. > > -- Jim > -- Luther KB5QHUAlma, Ark '87 300SDL (270,491 mi) head case? '83 300SD (241 kmi) '82 300CD (162 kmi) '82 300D (74 kmi) needs MAJOR engine work '85 300D (280,176) parts car
Re: [MBZ] GP Infant Mortality
Got my 2 new GPs today so tomorow I'll try to find out what the problem is. To refresh memory - I have new GPs and new GP relay - preglow light goes out within 1 sec. of turning the key) That sounds like a problem internal to the GP relay. These things are likely NOS, not new-new, and the timing capacitor could have aged to death before you ever got it. I got my DMM out and set it to Resistance - using a new GP I touched the threads at the top and the threads that contact the cylinder head - got a reading of .3 - then I crossed the leads and the reading was .0 - is it OK that my DMM doesn't have a reading greater than .0? Yes, you just cross the leads to find out what its idea of zero is, and then subtract that from your reading. How do I tell if my DMM will measure current in the range you mentioned -- Was it exceedingly expensive? Then maybe. It's usually clearly written on the face somewhere, if it does current at all. I'm thinking I need at least a 30A max? But I think my DMM is good for 0A's - it's from Radio Shack -- Most DMM's have a 10A current scale, if they have anything at all. To measure more requires a shunt, rarely seen these days, or a relatively expensive clamp-on DC ammeter probe. Even my $300 Fluke only goes to 10A without the 400A external probe (another $200 IIRC). Attempts to measure more than 10A results in blowing its internal fuse, an item that costs more than an entire DMM from Harbor Freight. An old-fashioned charging gauge from the auto parts store could work, those are usually 60A over a half-scale, so are a bit too crude to get a good measurement off of. It would have detected my one bad one that had 2x normal current, however. -- Jim
Re: [MBZ] GP Infant Mortality
Hi Jim, You wrote:
Re: [MBZ] GP Infant Mortality
Now, bear in mind I'm electrically challenged ;-) - so, I remove the plug from the relay and set my meter to resistance - automatic scaling - and with one wire to ground I touch the other to the plug going to a GP and read the resistance? Exactly. Nominally 0.6 ohms engine cold, but on a warm day. Don't forget to subtract any value that you get off the meter with the two leads shorted together, low-ohms readings can be tricky that way. BTW - I sent a seperate email with this question - but is there a preference between Beru GPs and the much lower priced Bosch? I suspect Beru are OE. My understanding is that the Beru are preferred. More durable or something like that. I've used both. -- Jim
Re: [MBZ] GP Infant Mortality
Thanks Jim, I'll try to measure the resistance - Now, bear in mind Im elecricall challenged ;-) - so, I remove the plug from the relay and set my meter to resistance - automatic scaling - and with one wire to ground I touch the other to the plug going to a GP and read the resistance? I'm sure I'll figure it out. BTW - I sent a seperate email with this question - but is there a preference between Beru GPs and the much lower priced Bosch? I suspect Beru are OE. After removing the intake manifold and the metal fuel inj lines to access the GPs I'm in no hurry to do it again because one decided to die. But, it looks like that's what I need to do - but this time, if Beru is preferred that's what I'll use - Thx - Larry T (67 MGB, 74 911, 78 240D, 91 300D) www.youroil.net for Oil Analysis and Weber Parts Test Results http://members.rennlist.com/oil PORSCHE POSTERS! youroil.net Weber Carb Info http://members.rennlist.com/webercarbs Porsche Road Test http://members.rennlist.com/roadtest/ . - Original Message - From: "Jim Cathey" <[EMAIL PROTECTED]> To: "Mercedes Discussion List" Sent: Saturday, October 14, 2006 8:20 PM Subject: Re: [MBZ] GP Infant Mortality I replaced my GPs and the GP relay within the past 3 weeks or so. Yesterday, the preglow light came on for only a second or less - even though it was in the upper 40s and hadn't been started since the night before - it was stone cold - it started instantly although it runs like one cylinder isn't firing evenly. Within a minute the engine idles & runs smoothly. That's way too quick. No wonder it ran poorly. I'm wondering about the possibility of a GP being bad out of the box? Certainly. The relay, too. It happens. 'New' relays usually are new old stock, and the internal components can fail with age, though not so much as with use. Most likely is the GP, or its wiring. Also - is there a way to check each GP without removing them Sure. The quick way is to pull the plug off the GP relay and use a DMM to measure the resistance to ground of each one. The rated value is 0.6 ohms, though it can vary with temperature. The important part is that they all be about the same. Even better is to use a hefty ammeter to measure the current to each one. I just did that on the 190D a couple of days ago. Within a couple of seconds each one dropped from about 28A to under 20A, except for the bad one that was drawing about 2x normal current. (_That_ is a weird failure mode.) Most people don't own an ammeter that is good for more than 10A, however. The GP's seem to be pretty basic - but I guess the innards could be bad in one. They are pretty basic, but they're not as simple as the old series plugs. -- Jim ___ http://www.okiebenz.com For new parts see official list sponsor: http://www.buymbparts.com/ For used parts email [EMAIL PROTECTED] To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.408 / Virus Database: 268.13.4/475 - Release Date: 10/13/2006
Re: [MBZ] GP Infant Mortality
Hi Luther, Nope - zero carbon buildup - when I changed the GPs I was prepared with a reamer to clean any out needing it - none had any carbon build up. Of course, for the last 8 months I've been running a heavy duty cylinder head treatment to remove all the carbon - called Ferox 230. It corrected a cold running problem I had and as far as I can tell it completely cleaned the carbon from the head. Anyway - thanks for the help -- ;-) Larry T (67 MGB, 74 911, 78 240D, 91 300D) www.youroil.net for Oil Analysis and Weber Parts Test Results http://members.rennlist.com/oil PORSCHE POSTERS! youroil.net Weber Carb Info http://members.rennlist.com/webercarbs Porsche Road Test http://members.rennlist.com/roadtest/ . - Original Message - From: "Luther Gulseth" <[EMAIL PROTECTED]> To: "Mercedes Discussion List" Sent: Saturday, October 14, 2006 6:42 PM Subject: Re: [MBZ] GP Infant Mortality is there any carbon build up around the GP's? That will kill a GP quick. You might need to ream out. I used several old GP's and flattened them with a hammer and run them down tight to scrape out the carbon. On Sat, 14 Oct 2006 17:33:34 -0500, LarryT <[EMAIL PROTECTED]> wrote: Howdy - I replaced my GPs and the GP relay within the past 3 weeks or so. Yesterday, the preglow light came on for only a second or less - even though it was in the upper 40s and hadn't been started since the night before - it was stone cold - it started instantly although it runs like one cylinder isn;t firing evenly. Within a minute the engine idles & runs smoothly. I'm wondering about the possibility of a GP being bad out of the box? Also - is there a way to check each GP without removing them - it's a PITA on a 1991 300D 2.5T. ;-) Don't know how successful I'll be but I plan to see if I can wiggle my hand past all the in the way to see if I can detect any loose wires. The GP's seem to be pretty basic - but I guess the innards could be bad in one. BTW, everything on this car looks to be in perfect condition - all the wiring looks new with no corrosion - there's only 114k on this car. Thx - Larry T (67 MGB, 74 911, 78 240D, 91 300D) www.youroil.net for Oil Analysis and Weber Parts Test Results http://members.rennlist.com/oil PORSCHE POSTERS! youroil.net Weber Carb Info http://members.rennlist.com/webercarbs Porsche Road Test http://members.rennlist.com/roadtest/ . -- Luther KB5QHU Alma, Ark '87 300SDL (270,491 mi) head case? '83 300SD (241 kmi) '82 300CD (162 kmi) '82 300D (74 kmi) needs MAJOR engine work ___ http://www.okiebenz.com For new parts see official list sponsor: http://www.buymbparts.com/ For used parts email [EMAIL PROTECTED] To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.408 / Virus Database: 268.13.4/475 - Release Date: 10/13/2006
Re: [MBZ] GP Infant Mortality
30-0-30 ammeter is the best way. On Sat, 14 Oct 2006 19:20:04 -0500, Jim Cathey <[EMAIL PROTECTED]> wrote: >> I replaced my GPs and the GP relay within the past 3 weeks or so. >> Yesterday, the preglow light came on for only a second or less - even >> though >> it was in the upper 40s and hadn't been started since the night before >> - it >> was stone cold - it started instantly although it runs like one >> cylinder >> isn't firing evenly. Within a minute the engine idles & runs smoothly. > > That's way too quick. No wonder it ran poorly. > >> I'm wondering about the possibility of a GP being bad out of the >> box? > > Certainly. The relay, too. It happens. 'New' relays usually are > new old stock, and the internal components can fail with age, though > not so much as with use. Most likely is the GP, or its wiring. > >> Also - is there a way to check each GP without removing them > > Sure. The quick way is to pull the plug off the GP relay and use a > DMM to measure the resistance to ground of each one. The rated value > is 0.6 ohms, though it can vary with temperature. The important part > is that they all be about the same. > > Even better is to use a hefty ammeter to measure the current to each > one. I just did that on the 190D a couple of days ago. Within a couple > of seconds each one dropped from about 28A to under 20A, except for the > bad one that was drawing about 2x normal current. (_That_ is a weird > failure mode.) Most people don't own an ammeter that is good for more > than 10A, however. > >> The GP's seem to be pretty basic - but I guess the innards could be >> bad in >> one. > > They are pretty basic, but they're not as simple as the old series > plugs. > > -- Jim > -- Luther KB5QHU Alma, Ark '87 300SDL (270,491 mi) head case? '83 300SD (241 kmi) '82 300CD (162 kmi) '82 300D (74 kmi) needs MAJOR engine work
Re: [MBZ] GP Infant Mortality
High current draw is usually the result of the internal coil grounding on the side back from the tip rather than at the tip as it's supposed to. A white hot spot on the side doesn't help starting much. The other failure is for the wire to pull through at the tip, leaving a neat little hole. In that case, the circuit will be open (infinite resistance). You probably have a loose wire. Peter
Re: [MBZ] GP Infant Mortality
I replaced my GPs and the GP relay within the past 3 weeks or so. Yesterday, the preglow light came on for only a second or less - even though it was in the upper 40s and hadn't been started since the night before - it was stone cold - it started instantly although it runs like one cylinder isn't firing evenly. Within a minute the engine idles & runs smoothly. That's way too quick. No wonder it ran poorly. I'm wondering about the possibility of a GP being bad out of the box? Certainly. The relay, too. It happens. 'New' relays usually are new old stock, and the internal components can fail with age, though not so much as with use. Most likely is the GP, or its wiring. Also - is there a way to check each GP without removing them Sure. The quick way is to pull the plug off the GP relay and use a DMM to measure the resistance to ground of each one. The rated value is 0.6 ohms, though it can vary with temperature. The important part is that they all be about the same. Even better is to use a hefty ammeter to measure the current to each one. I just did that on the 190D a couple of days ago. Within a couple of seconds each one dropped from about 28A to under 20A, except for the bad one that was drawing about 2x normal current. (_That_ is a weird failure mode.) Most people don't own an ammeter that is good for more than 10A, however. The GP's seem to be pretty basic - but I guess the innards could be bad in one. They are pretty basic, but they're not as simple as the old series plugs. -- Jim
Re: [MBZ] GP Infant Mortality
is there any carbon build up around the GP's? That will kill a GP quick. You might need to ream out. I used several old GP's and flattened them with a hammer and run them down tight to scrape out the carbon. On Sat, 14 Oct 2006 17:33:34 -0500, LarryT <[EMAIL PROTECTED]> wrote: > Howdy - > I replaced my GPs and the GP relay within the past 3 weeks or so. > Yesterday, the preglow light came on for only a second or less - even though > it was in the upper 40s and hadn't been started since the night before - it > was stone cold - it started instantly although it runs like one cylinder > isn;t firing evenly. Within a minute the engine idles & runs smoothly. > > I'm wondering about the possibility of a GP being bad out of the box? > Also - is there a way to check each GP without removing them - it's a PITA > on a 1991 300D 2.5T. ;-) Don't know how successful I'll be but I plan to > see if I can wiggle my hand past all the in the way to see if I can detect > any loose wires. > > The GP's seem to be pretty basic - but I guess the innards could be bad in > one. > > BTW, everything on this car looks to be in perfect condition - all the > wiring looks new with no corrosion - there's only 114k on this car. > > Thx - > > Larry T (67 MGB, 74 911, 78 240D, 91 300D) > www.youroil.net for Oil Analysis and Weber Parts > Test Results http://members.rennlist.com/oil > PORSCHE POSTERS! youroil.net > Weber Carb Info http://members.rennlist.com/webercarbs > Porsche Road Test http://members.rennlist.com/roadtest/ > . > -- Luther KB5QHU Alma, Ark '87 300SDL (270,491 mi) head case? '83 300SD (241 kmi) '82 300CD (162 kmi) '82 300D (74 kmi) needs MAJOR engine work
