I'd think it indicates that they are a problem; disconnect the GP relay on the "good" one to find out.
BTW, GP relays can completely and utterly fail yet still be able to light the light; it seems to happen to the ones that have small slotted head screws holding the case together; one at each corner of the side with all the electrical connections. The two halves of the case have a gasket/o-ring cross-section type of seal between them which can shrink (linearly, not diametrically) and split, leaving a gap through which water can infiltrate. When this happens on the side that mounts to the car, water can get close enough to be drawn in by capillary action. The water gets in and shorts out the electronics; mine was more than half full. (If your GP relay is glued/welded/non-openable, this failure cannot occur) This mode of failure seems particular to instances where the GP relay is mounted vertically beneath the hood/fender joint (I had it happen in an '85 300D, but not in an '84 300SD)... I suspect that water infiltration could also be an issue with relays that were missing the protective cap that covers all the electrical connections; the plastic pin in the place of the sixth GP pin has a vent hole in the very top... Then there are the frakko brand electrolytic crapacitors, which seem to start failing after 10 years or so; this is also what takes out many CC amps... When I had two OM 617's I kept a spare GP relay (and a set of plugs) on the shelf. Using and removing the injection lines, you can replace all of them, including the back one, in about half of an hour... -- John W Reames jwrea...@comcast.net Home: +14106646986 Mobile: +14437915905 On Dec 15, 2010, at 16:56, andrew strasfogel <astrasfo...@gmail.com> wrote: > Another question. The "good" 300TD starts without glowing when the > engine is warm. The "bad" 85 300TD always needs to be glowed before > starting, regardless of engine temperature. It starts quicker when > it's warm, but I still need to glow it or it cranks a lot. Does this > observation mean the glow plugs aren't the problem? > > On Wed, Dec 15, 2010 at 9:12 AM, Rich Thomas > <richthomas79td...@constructivity.net> wrote: >> Yeah that sounds right. I forget these things, maybe I should use a >> notebook or something when doing these jobs. But those gearwrenches are >> great tools. >> >> --R >> >> On 12/14/2010 10:35 AM, John Reames wrote: >>> >>> An 8mm gearwrench for the electrical connections, and a 10mm for the plugs >>> proper. >>> >>> -- >>> John W Reames >>> jwrea...@comcast.net >>> Home: +14106646986 >>> Mobile: +14437915905 >>> >>> On Dec 14, 2010, at 10:28, Rich >>> Thomas<richthomas79td...@constructivity.net> wrote: >>> >>>> Might want to check your glow plugs, relay, and CHECK YOUR FUSE. The 84 >>>> SD was getting a bit balky, even in warm weather, I replaced a couple of >>>> glow plugs and the relay (which did not appear to be relaying very well for >>>> reasons unclear), and it fires right up (though I have not yet tried it >>>> today after last night way down in the 20s). I CHANGED THE FUSE too, first >>>> thing, but it was OK so that was not the issue. Sort of minimal stuff that >>>> you should probably check as a matter of course, but makes quite the >>>> difference. >>>> >>>> Note: changing the glow plugs really benefits from a 10mm (I think) >>>> gearwrench as that is about the only thing I could fit in there easily to >>>> loosen/tighten everything. The relay is easy to change, make sure you >>>> disconnect the battery first. >>>> >>>> --R >>>> >>>> On 12/14/2010 10:14 AM, andrew strasfogel wrote: >>>>> >>>>> This is a new problem for me. The 1985 300TD recently had a valve >>>>> adjustment so I wasn't too worried about it starting in the cold. >>>>> Well, I should have been! Yesterday, with a temp of around 23 F., >>>>> after sitting in the street for a mere 6 hours the 300TD barely >>>>> started up without running down the (relatively new) battery. I had >>>>> to key the glow cycle three times for an additional 10-20 seconds each >>>>> time before it fired up. >>>>> >>>>> So how do I diagnose whether this is bad glow plugs or low >>>>> compression? Or could it be something else? The car never fires up >>>>> quickly in the best of circumstances, compared to the '83 turbo diesel >>>>> wagon, although it has adequate power and acceleration. Fuel is >>>>> clean, too (I recently changed the tank strainer and other filters). >>>>> >>>>> As always, TIA. >>>>> >>>>> Andrew >>>>> 1983 300TD starts like a 300TE >>>>> 1985 300TD needs to be wound up >>>>> >>>>> _______________________________________ >>>>> http://www.okiebenz.com >>>>> For new and used parts go to www.okiebenz.com >>>>> To search list archives http://www.okiebenz.com/archive/ >>>>> >>>>> To Unsubscribe or change delivery options go to: >>>>> http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com >>>>> >>>> _______________________________________ >>>> http://www.okiebenz.com >>>> For new and used parts go to www.okiebenz.com >>>> To search list archives http://www.okiebenz.com/archive/ >>>> >>>> To Unsubscribe or change delivery options go to: >>>> http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com >>> >>> _______________________________________ >>> http://www.okiebenz.com >>> For new and used parts go to www.okiebenz.com >>> To search list archives http://www.okiebenz.com/archive/ >>> >>> To Unsubscribe or change delivery options go to: >>> http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com >>> >> >> _______________________________________ >> http://www.okiebenz.com >> For new and used parts go to www.okiebenz.com >> To search list archives http://www.okiebenz.com/archive/ >> >> To Unsubscribe or change delivery options go to: >> http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com >> > > _______________________________________ > http://www.okiebenz.com > For new and used parts go to www.okiebenz.com > To search list archives http://www.okiebenz.com/archive/ > > To Unsubscribe or change delivery options go to: > http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com _______________________________________ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
