e320 water pump. level of difficulty?
 

what is the level of difficulty in replacing the water pump in a e320.

after replacing the coolant and thermostat, the car still overheats but only when idling.

How many miles are on the fan clutch?

I would say this is the most difficult dyi job I have ever done. However, I have done three of them, so it's not very intimidating, just very time consuming and a lot of back bending.

If you are not weeping or leaking it is likely the fan clutch. You absolutely have to have a thermostat in the car. It's counter intuitive...but our cars need a thermostat to keep cool.

I guess you have already determined your aux fans are fine.

i haven't even considered the fans.

what's the procedure for checking the fans?

i don't think the wp is weeping.

With the engine as hot as it will get shut it off and see how hard the fan is to turn. If it is easy then you need a new fan clutch. Worn ones are easy to stop with your hand while the engine is running but I would not recommend to anyone to stick there hand in there.

I suggest a tightly rolled up newspaper.

Check your radiator for cold spots , you also have seperate low speed and high speed fan control, unscew fuse box cover and look at blue and green fuses and check them out, is your coolant mixture 50%?,is your cap holding pressure?

benhogan, what's the mileage on your 1995 E320? When was the water pump changed last? As mentioned it's critical that the viscous fan clutch and auxiliary fans are working properly. If not, replacing the water pump will not resolve your overheating problem at idle.

After diagnosing the overheating problem further if you need to replace the water pump suggest buying a reconditioned water pump at your local MB dealer.

is the big fan behind the radiator supposed to keep running AFTER you take the key off?

it is not turning unless the motor is running.

It is connected to the front of the engine isn't it?

yes.

it is easy to turn. so i guess i need a fan clutch.

i've never replaced one before.

There is an allen head fastener in the center of the fan that will need to be removed (conventional threads). You will need to hold the belt with an old belt wrapped around it with vise grips or there is a place in the back that you can lock it in place with a small rod bent at a certain angle at the end. I'll try to get a pic of what I use over the weekend. Replace the fan clutch first if it is easy to turn when the engine is at operating temperature.

is it harmful to drive it as it is? it does not really overheat unless i am stuck in traffic

It should not hurt it at all as long as it does not get up in the red. On one of my E300's I don't even have a fan shroud on it. It will get slightly over 100dC but that is all.

Something I've noticed on hi performance BMW's and MB's is that the radiator is only being used at around 25-40% capacity at 80 mph (based on cleanliness/newness, etc...).