Overheating @ idle
 

I have a 1987 MB 190E 2.3 that’s overheating at idle. It maintains a steady temp when driving. So, this tells me that the cooling system is working, somewhat. From the research I have done it has to do with a Cooling Fan. I’ve looked at the fan mounted on the engine and it spins freely. I’m not sure if it should do this (possibly and bad fan clutch?). Any suggestions? Just want to make sure I’m barking up the right tree before I drop some cash on a new part. I plan on fixing it myself.

Thanks

Electric clutch or visco clutch?

If electric clutch (as I think it is), you need to check operation (temp sensor switch) and engagement. If it switches on but doesn't speed the fan up, you need a new clutch, if it never switches on, you need to fix the sensor system.

I'm not very familiar with it, though...

Peter

Parts book lists it as electric clutch (magnetic) for your car, so follow Peter's suggestion.

Please define "overheating". Is it boiling over or is the temp. just going up? It's normal for the temp to increase at idle and low speed driving, particularly in warm weather.

Does the engine have and electromagnetic fan clutch ofra themo fan clutch? At about 100C the engine fan should engage via either the electomagnetic clutch or the thermo clutch. At about 105C the electric fan should engage at high speed.

Duke

I believe I have an electromagnetic clutch according to the parts listing.

Yes, it is overheating and boiling over at idle.

I see two fans, one attached to the engine block and one in front of the radiator; I believe this one is associated with the transmission. Is it possible that neither fan sys is working?

I'm guessing it could be the temp switch, fan clutch or wiring. The radiator, fans, and fan shrouds appear to be in good condition.

How should I go about troubleshooting the fan system?

My A/C system is not working either, which is fine, but will it have any effect on the engine cooling system?

Thanks for your help

Check your fuses -- I'll bet they are all in bad shape, and the ones for the fan clutch and aux fan have cracked.

Treat yourself to a new pressure cap, too. Your's is probably bad, as it shouldn't boil over until the needle gets close to the red zone.

Peter

Most auto parts stores have pressure cap testers. It should hold about 15 psi. With a 15 psi cap and a 50/50 mix of antifreeze and water, boilover should not occur until at least 120C.

If the fans are operating properly is should never exceed 110C. What is the maximum reading you are seeing on the temp gage?

The electromagnetic engine driven fan clutch should engage at about 100C and you should hear it click. When engaged you should feel much more air flow and hear more fan noise when the engine is revved up. The electric fan should engage at about 105C.

As Peter said, the fuses are a good place to start, then check the temperature switches.

Duke

Also test your thermostat by dropping it in a pan of "almost" boiling water. It should open at about 190 degrees F, or 87 C. Check water temp with your turkey thermometer. A sticking thermostat will cause all of the above problems.