I own an 84' 190D with 82,000 miles on it with a new radiator. Now my car is running at an average of 100 degrees celcius which I think is high. (maxes out at 120 degrees). It used to completely overheat before I got the new radiator, the radiator hose used to blow off of the radiator and vapor would pour out.

I've noticed that if I drive slower then 60mph, my temp guage wobbles back and forth from 80 degrees, but primarily goes to 100. However, if I'm traveling at an excessive speed 60mph or greater, the temp primarily stays at 80-85 degrees. I think 80 degrees is where it should stay all the time personally.

Inside the engine compartment, the fan behind the radiator has a lot of slip, though it spins a little....meaning I can grab the fan and prevent it from moving with little effort even though the belts are still moving. Shouldn't it be moving just as fast as the belts are when the car is parked and not be able to have slip at all?

Also the fan nearest to the grille of the car. Is it for air conditioning? I never have seen this fan move. I don't know whether it is a fan problem, water pump problem, thermostat, etc. Any suggestions would be great.

 

Fan clutch. And replace the themostat there cheap and fail often 80-90 is normal and 100 is a bit high. Plus overheating is worse on a diesel that a gas. Low miles man get the car fixed right ok.

 

Not real sure about the front fan but mine only runs when its really hot out like 90F plus.

 

I figured the fan clutch. How sure are you on that though? Also, where is the best place to buy one?

Will replacing the fan clutch make my fan not slip?

 

The best place to but one would be at Potomac German Auto on Lime Kiln Road on RT. 85. As far as the fan being able to be stopped by hand very sure nothing is 100% but it would be the first thing i would try. Plus i am very strong suggesting u change the themosat and buy one that when it fails that it will fail in the open and not closed position and auto supply will have it.

 

What exactly does a thermostat and fan clutch do? Just curious

 

Thermosat opens and closes letting coolant into the motor once it has warmed up the operating temp.

Fan clutch turns the fan on once the engine temp is high enough to engage the clutch.

 

So the fan clutch is basically an electric motor

 

No the fan clutch is based on a principle in which heat expands or contracts a metal inorder to engage a clutch.

 

I'd imagine most of us saw my thread about the car overheating. Did you make sure your belt is tight? That made my situation peachy. For what it's worth, my temps are perfect now and my fan still moves very freely of the pulley it's on. I don't claim to be an expert or anything, but I think that for the most part, the "fan clutch" in these older diesel mercedes is all but nonfunctional, the top priority being that the fan is allowed to move independently of the pully when you are on the highway and wind is coming at the fan much faster than the engine wants to turn it (so the belt doesn't snap).

But if the fan is moving slow enough that it's not a blur, ie you can see the individual blades moving at idle, then yea that's your problem IMO.