ThreeE's

Hey guys, first time posting. Hope I can get some advice. My 1990 300E seems to be running warm during the following conditions:

First off, it's been in the 90's-100's in temperature lately.

-On Steep highway grades, the coolant gets close to being at the 100 degree C. line.

-In traffic stops, the needle creeps up, just about to the 100 degree line.

-After driving, and I turn the car off, if I leave the car on ACC mode, the coolant will get to the 100 degree line after the car is off.

On some cars I've owned, the electric fan motor goes on after driving to cool the engine once the car is off. Is that the case on the W124's? Should it be going on?

I've verified that the two accessory fans in front of the radiator do go on when the engine and AC is on.

I opened the coolant resevoir and it looked like there was fluid in there. It appeared to be clear liquid, not the colored stuff you usually find. Not sure who changed it last or what they put in.

Otherwise, the car is great. A/C is cold, all electrical accessories work fine and everything is original. Love the car, just don't want to ruin it with over heating/stressing the 18 year old beauty.

Thanks, your help is appreciated

As well,

neanderthal

dont worry about it

100 is within the operational parameters designed for the engine. you should worry if its constantly in the 100s and edging towards 120.

in my car (i live in northridge) i run pretty much straight water in summer and if the level gets low (which it does as my car consumes water (slowly) and oil) towards winter i add anti freeze.

ThreeE's

Thanks for the response. If you turn your car off after running it, when the temp is right around 80c does it rise up after the car is off? ie...leaving it in the ACC mode so that the gauges still work....and seeing if the temp rises? I've never noticed this before in the car so I was concerned. As you know, we've had very hot temps lately so I wasn't sure if something was wrong or if the extreme heat caused this.


Thanks for the response.

CaliE320

If you're not sure what kind of fluid it is, then I suggest you flush and fill with the proper MB fluid and add water wetter along witha new thermostat.

~Cali

ThreeE's

I think I'll bring it in for that. Do you know about how much a thermostat should cost? I assume it's not much. A flush is probably in order as the car sat for about a year with very minimal usage.

X03

I've been having the same problem that you just described for a while now... i never had the chance to take it down to the mechanic and always had to wait in the car after I turned it off to turn on the heater because it would shoot up to 100+ and close to 120.

Anyways, finally took it in and he said its the temp gauge thats faulty. He switched my instrument panel with another car and said it ran fine w/out overheating and drove with the A/C on. He even laser'd it or whatever and it wasn't overheating. I am waiting for the part to come in from ebay because the dealer wanted $1000 just for that small temp/gas/oil gauge. ridiculous i swear... so possibly something you might want to look into

ozopera

i think 100+ is common on 300e, When I used to have 300e, I will wait until the temp goes down below 100+ before it shut it down.

I believe the electric fan has 2speed for 300e, check the fuse/relay on the fuse box, make sure the fuse is OK! If the fuse busted your electric fan only work in low speed, never go to second speed.

mr300ce

Don't just guess at things. It could cost you (or someone reading these forums) lots of $$$$.

100*C is 212*F (F* = what we here in the USA are used to). So, best thing to do is ALWAYS use a 50/50 mix (unless you live in frozen north) of Mercedes coolant and water. (Water Wetter does work to loew operating temp, I've run extensive tests).

Boiling Points & Pressures
Pressure Boiling - Temp. (Deg. F)
0psi - 212*F (100*C) Sea level
4psi - 224
7psi - 232
9psi - 237
13psi -246
14psi -249


Note: Boiling point drops with altitude. At 2,500 feet, water boils at 207 degrees; at 5,000 feet, 202 degrees; at 7,500 feet, 198 degrees; at 10,000 feet, 193 degrees. Sea-level atmospheric pressure is 14.7 psi. By contrast, at 10,000 feet, atmospheric pressure is 10.0 psi.


NEVER run straight water. Corrosion will KILL your engine.

A new radiator cap (20psi) is a good thing, as that will raise the boiling point a whole lot.

A new thermostat every 2-3 years is a good thing.

The electric fans are 2 speed. Low is ONLY for A/C operation.

High comes on ONLY when engine coolant temps get REALLY hot.

The mechanical fan clutch has a WHOLE lot to do with engine temp staying in the correct range.

Check it for proper operation, and change if not working properly.