On Sat, 13 Jul 2013 20:33:37 -0600 Craig <diese...@pisquared.net> wrote:
> On Sat, 13 Jul 2013 19:33:18 -0500 Peter Frederick
> <psf...@earthlink.net> wrote:
>
> > Ye gods that's an old post!
How about a couple from "der Dieseling Doktor"?
====================================================================
From: Marshall Booth <mboo...@pitt.edu>
To: die...@mbz.org
Reply-To: die...@mbz.org
Subject: Re: Fan clutch test procedure (was: RE: [DIESEL] RE: Running
hot underload)
Date: Tue, 04 Jun 2002 16:17:50 -0400
Sender: owner-die...@mbz.org
Organization: University of Pittsburgh School of Medicine
X-Mailer: Mozilla 4.79 [en] (Windows NT 5.0; U)
Here's the test I was looking for from Hank van Cleef:
> Ray, with the engine cooled off and stopped, you should be able to
> turn the fan blades fairly easily, and feel some drag---but it should
> turn with far less torque than needed to slip the pulley on the belt.
> Just a few inch-pounds. Hot (around 95C) a thermostatic spring turns
> a valve so that the silicone inside flows into the coupling chambers,
> but this is just another version of a fluid coupling, so the blades
> will still be fairly free to turn with the engine stopped. That's the
> reason for doing the "roar test" with the engine hot. The most common
> failure is failure to engage hot. If the aux fan is running, and the
> engine fan doesn't follow engine speed increase and make lots of noise
> and blow lots of air at 2000-2500 RPM, it's not passing the roar test.
> However, with the mechanism mechanically seized up, you've got a
> solid fault diagnosis before you start the engine.
>
> There is a centrifugal valve, separate from the temp valve, that dumps
> the fluid out of the chambers at about 3500 RPM. That is there to
> prevent the fan from overspeeding and throwing blades (which really
> can do a lot of damage). If the whole thing is siezed up, you've got
> an internal mechanical failure, and the "get you home solution" is to
> take it off the car and run without it until you can replace it. Of
> course, that means inadequate cooling below about 40 mph steady speed
> at 70F outside air temperature. The alternative is to leave it on,
> but keep the engine below 3000 RPM, and I consider that also a "get
> you home" strategy only.
>
> --
> Hank van Cleef
> 1986 420SEL
>
Marshall
======================================================================
From: Marshall Booth <mboo...@pitt.edu>
To: die...@mbz.org
Reply-To: die...@mbz.org
Subject: Re: [DIESEL] Temp variation
Date: Tue, 11 Jun 2002 21:29:12 -0400
Sender: owner-die...@mbz.org
Organization: University of Pittsburgh School of Medicine
X-Mailer: Mozilla 4.79 [en] (Windows NT 5.0; U)
Pete, The 15 degree rise you refer to takes the temperature from the
point where it is depending entirely on passive air flow and the flow of
the pumped water up to the point where the main and aux fans cut in (at
100-105 deg C) and increase air flow at low speeds. If the thermostat is
not opening fully, then less heat will need to be generated for the temp
to creep up to 100-105.
All other things being equal, and I quote from a very well informed man
(Hank van Clef), "...in general, loss of cooling control at high speed
is generally related to coolant flow problems; at low speed, air flow
problems. Dirty fins will act like high speed troubles." Warm temps,
high humidity, and city speeds with the AC on put the ultimate stress on
an auto cooling system.
Marshall
--
Marshall Booth
"der Dieseling Doktor" mboo...@pitt.edu
'87 300TD 150Kmi,'87 190D 2.5 205Kmi, '84 190D 2.2 224Kmi, '85 190D 2.0
154Kmi, '87 190D 2.5 turbo 200+kmi, '84 190D 2.2 234Kmi dismantled
Diesel Technical Advisor MBCA, member GWSection
http://www.dhc.net/~pmhack/mercedes/mbooth1.htm
Pete Dunbar wrote:
>
> What do you all see as far as cooling temperature variation on a hot
> day? My 190 usually holds at about 85 degrees no matter what, but my
> E300D will rise up about 15 degrees on a hot day with the AC on. That
> is not too surprising and it cools right back to 85 ish once you get
> moving as you would expect. I'm wondering about it rising up to 100 C
> though, do those thermostats sometimes fail by not opening all the way
> up? Is a 15 degree variation a problem or pretty normal for these
> diesels?
>
> Pete D 1987 190 D 2.5 turbo, 210,000 mi
> 1995 E300D, 120,000 mi
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