How many diesel owners have had problems with overheating????? - PeachParts Mercedes-Benz Forum

RLNAMERCEDES100 · #1 09-08-2002, 07:12 AM

I have had to bake all summer because I cannot run the AC when I'm in town because my car starts to overheat. I have done all the necessary work to it to prevent it from doing it but still steaming. I have read a few other posts of peoples cars getting hot. How many people have had problems with their car overheating for no apparent reason???

CHAPP · #2 09-08-2002, 07:31 AM

I did everything also...flush, themostat, etc. I changed my Radiator before it got hot...I have been cool all summer. With your engine warmed up..the bottom hose and the top hose should be close to the same temp. if not ...change the radiator.

RSH · #3 09-08-2002, 03:57 PM

No problems with my 1983 300SD even on 100+ degree days with a/c full blast, yesterday I did do a flush and refilled with prestone 5/150 orange coolant, now it seems to run even cooler.

P.E.Haiges · #4 09-08-2002, 04:39 PM

RLNA,

First, have you checked the thermostat? Try removing it and running without it. If the overheating problem goes away, try a new thermostat.

If the thermostat isn't your problem, remove the radiator and take it to a radiator shop that has a live steam flush system and have the radiator cleaned. That cured my 300SD that used to run on the hot side in the dessert

Cost: about $35.

While you have the radiator out, pull the water pump and make sure the impeller isn't loose on the shaft. If the impeller is loose, weld it to the shaft. You probably won't need the radiator cleaned if you have a bad water pump and fix or replace it.

P E H

Holson Adi · #5 09-08-2002, 08:27 PM

Try replacing the Thermostat. You can get it from Fastlane here. I got it from Autozone because I needed to get it done during the weekend and Autozone's a walking distance from my apartment.

The Autozone T-Stat is made by Wahler and is cheap! The previous T-Stat was also a brand new unit also by Wahler (just looks a lil different) that was bought from the Benz Dealer.

That Dealer T-Stat did not open until the engine was running at 98-100 Deg C! On a very hot summer day (95+F), the t-stat opened promptly. But, when it got colder (60-70F here) the car was running at 95-100 Deg! unless I punch it and drive it hard... once I start driving slower the temperature went up again and the lower radiator hose was cold.

The reason why I put that dealer supplied Wahler was that my car would run really cool but in traffic it went up to 105 easily (without A/C) and found out that the old T-stat had snapped.

But, what do you mean by overheating. How hot does it run?

#6 09-08-2002, 10:33 PM

I had the opposite problem; my 300CD was not getting up to operating temperature. I replaced the T-stat, and that fixed the problem, and it seems to not get hot in the summer.

#7 09-08-2002, 11:47 PM

Didn't read all the posts here so- sorry if redundant. I had this problem and turned out to be a fan clutch. I bought a new one (without fan) for a great price at fast lane-(phil) and replaced it easily. Problem solved!

The Warden · #8 09-09-2002, 12:19 AM

TANK, how much was it just for the clutch?

I'm pretty sure I need a fan clutch as well (I have never hear the fan spool up), along with an aux electric fan...car runs at a good temp while driving, but the temp gauge starts creeping up while sitting at idle...

RLNAMERCEDES100 · #9 09-09-2002, 04:55 AM

My car is a 1987 300D turbo 3.0. On the highway it pretty much stays in the 85-95C, but when I'm in traffic it goes almost to the 120C. Do you really think it might be the T-stat?

engatwork · #10 09-09-2002, 05:25 AM

RLN - Seeing as how it goes up in traffic it means one of two things - there is not enough air flow through the radiator (fan clutch - I suspect this is the problem) or there is not enough water through the radiator (thermostat). I have seen the temperature stay elevated even at highway speed when the thermostat was the problem. Do a search on fan clutch and somewhere you will find the way to test it.

Holson Adi · #11 09-09-2002, 08:47 AM

Quote:

Originally posted by RLNAMERCEDES100
My car is a 1987 300D turbo 3.0. On the highway it pretty much stays in the 85-95C, but when I'm in traffic it goes almost to the 120C. Do you really think it might be the T-stat?

Well it could still be it.. I mean the T-Stat might not open fully or something. It is still worth checking. My problem was like that too. Just starting the engine and driving around (when it was mild and cold), the engine would barely heat up and on a cold day it ran at less than 80C.....

but on a hot day it overheated.

diesel don · #12 09-10-2002, 09:34 PM

All 3 of my 300's are running hot this summer. I became very alarmed when I was away from home, but am a bit calmer now that I see all of them up there.

I've done a few things like 70% water, water-weter and a flush. But nothing too radical.

Don

Piotr · #13 09-10-2002, 09:57 PM

I can't believe NOBODY mention fan switch.

I had the following symptoms- while driving over 65mph temp went up to 105-110C. In traffic/idling, the temp went to 120C. Needless to say the AC did not work. I replaced the fan clutch-NO CHANGE (after $290)! I replaced the t-stat- no change. Finally I replaced the fan switch. The temp would go up to 110C at idle, then fall down to 100C i.e. perfectly normal according to spec. But the temp above 65mph now reach about 110C . So I replaced the radiator and the temp went down to 95 C, again in accordance with the spec.

Then I tried to make my AC work and I found out that the aux fan was rusted-it turned but blew a fuse. I replaced the fan and coupled it with main fan-now temperature goes down from 110C to 100C in 10 seconds.

Your symptoms scream bad fan switch. I would try that before anything else-it's a $22.00, 10 minutes with the wrench fix and I BET your temp will not go over 110C.

By the way, after all of the above my temp went once to 105C while driving- the expansion tank pressure cap was bad. Also, the "new" fan switch went bad within a year. Bought the new one from a dealership - this one NEVER worked, finally I had my mech replace it at cost.

If your fan clutch is like mine, than it's electromagnetic and they VERY rarely go bad. Fan switches, however, are notoriously the culprit.

#14 09-10-2002, 10:12 PM

Hio Warden, sorry for my delay response, been busy these days. It was $165 +-shipped from fastlane. Make sure you don't buy the fan with it because you probably don't need it and it's lots more $$. ps My mechanic determined it was the fan clutch and gave me a price of $250+. I consulted with my friend and he showed me how easy it was to replace ourselves. I am not sure how exactly to determine whether this is the actual problem though.

Don't mean to contradict Piotr's helpful post, My tech said he has tons of cars, not sure if they were 126's, coming in with this problem considering the hot weather. Perhaps just coincidence.. My temp hardly ever reaches 90 degrees now and usually holds around 82.

CHAPP · #15 09-11-2002, 05:06 AM

Still beleive that your radiator could very well be your problem. These cars are old with old stopped-up radiators. They work great until it gets hot then they can't do the job...mine has plastic tanks and could not be cleaned. No running hot since replacing before summer. If you have metal tanks your's can be cleaned for around $50.