’84 300SD 233000 miles – decent shape – average MPG around 26-27
Had a new thermostat and M/B coolant installed first part of the year.
Installed all new belts in March this year.
Installed a new fan clutch a month ago – felt engine was running a tad warm (hovering around 100c way to much)
Radiator new in latter part of ’99 along with head gasket – less than 15000 miles

Situation: All of a sudden, stuck in L.A. stop and go traffic – temp gauge is sitting around 120C --- pulled over to shoulder stopped engine and checked water level (boiled out about a couple of quarts or so). Waited around 5 minutes, filled expansion tank and took off. Traffic sped up and temp fell to normal very quickly (a little below 90). I just shrugged it off.

Happened again, normal running at freeway speed, and very hot in traffic. No oil residue in expansion tank, or water in crankcase oil. I’m not having any of this garbage---
A friend suggested trying a “fail-safe thermostat” – never heard of um. Could be only two things – bad thermostat and or water pump (which looked like an original one).

Instead of fooling around with local parts houses and their aftermarket stuff, I bounced on Fastlane and ordered a BEHR thermostat and a new Laso pump.
From the time I placed my order via the website until items were in my paw –
--less than 24 hours -- although I’m not that far from Orange Co. (So. Calif.)
KUDOS PHIL
Installed the Behr thermostat (took out a Wahler less than 6 mo. old) and Laso pump (old pump wasn’t leaking or making noise, and looked as good as the new one, but since I had the new one and I intend on keeping this ‘mutha’ for a while --), and changed oil and filter just in case – cheap insurance. Overheating will kill a diesel faster then most anything! I speak from being around them for many years, both heavy equipment and high-horsepower big trucks.
--Situation remedied. -- Must have been the Wahler thermostat considering the old pump looked very good. Around a two hour job (I tend to take my time) which is VERY easy.

PS cleaning threads and using new bolts are a must for me. Old ones that held pump in almost caused a problem – could’ve twisted one or two very easily.

Jim

Jim:

Quality control on auto parts, even the German stuff (usually made in India these days) is going to hell. Bad thermostats out of the box are VERY common.

Only comment I would make is to replace the radiator cap, too -- I've had two bad ones now on 87 vintage cars, and have heard of several more at my local repair shop. Either won't hold pressure (the case on the 300TE -- fine until you stopped, and it blew coolant out) or won't vent vac, so the hoses are collapsed cold.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

There's been a lot of talk here recently about viscous fan clutches and auxiliary electric fans. Were the fans working properly?

The symptoms you described exactly matched those of my 240D which had a loose radiator cap and a faulty relay connection for the aux fan.

__________________
Rick Miley
2014 Tesla Model S
2018 Tesla Model 3
2017 Nissan LEAF
Former MB: 99 E300, 86 190E 2.3, 87 300E, 80 240D, 82 204D Euro
Chain Elongation References

Peter

Thanks very much for the radiator cap suggestion!
Sometimes I have a hard time seeing the forest for the trees -- even tho I live in one.


Rick

I replaced the viscous fan clutch which helped a tad. My aux. fan functions as designed and DOES come on even when the A/C is off. My car is an original California car and has not been modified that I am aware of. I'm the third owner.

I am convinced my problem was the Wahler t-stat. Temp now stays around 85 or so and "cycles" at about 95 or there abouts. Hard to be precise as the temp. indicator probably isn't right on the money.

As long as the needle doesn't hover around 100 I'm a happy camper.

olderdude,

You know on my 190D 2.2, the temp gauge also cycles in normal driving. I too had cooling probs and replaced coolant/hoses/theremostat. This certainly fixed the prob (bad thermostat), but it is funny how sometimes it can run a hair under 100 and other times it runs 'bout 85. I'd think that the thermostat would keep it pretty much the same at all times.

Still, I'm happy with the results.

Sholin

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What else, '73 MB 280 SEL (Lt Blue)
Daily driver: '84 190D 2.2 5 spd.

The Trax Gurkha 4WD made by MB subsidiary in India uses a OM 616 turbo engine. This engine comes with 72C thermostat which keeps the temps at 80c steady at 45c ambient temp outside and the max it would go up is 92c on a long hill climb. It uses a BEHR radiator but the thermostat is made localy and it is a brass one instead of the BEHR stainless steel job.

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