89 300ce leaking coolant from unknown part
 

I saw coolant leaking from that round black unit. Can anyone tell me what part is it and how to change it. Thanks.

That's the auxiliary pump for the climate control system. Are you sure the pump is leaking and not one of the hoses? I think removing and replacing is straightforward. Drain enough coolant so the level is below the pump beofre you touch the pump.

Sixto
95 S420
87 300SDL

didnt see your purple circle

I should get some sleep now

Sixto
Thank you very much. You are right, it is called auxiliary water pump. It costs about $200. I just spent all my $$$ to buy this 89 300 ce. I am broke and cannot afford replacing it now. I saw the coolant leaking in between the gap of the black plastic part with screws area. Does it have a ring in between or should I tight up the screws? What is the aux. water pump for? Will I get into big problem in the future if I do not replace it.

Try tightening the four screws, worked for me when I had the exact same leak on a 89 300e. The O ring is loose or bad at the mating surface of the plastic. Also during my search for the part name the cheapest price I found was from adsitco.com for $139.00 with free shipping. Hope this helps.

You need to fix this leak pronto (try the hints first) or bypass it and unplug it. If coolant gets into the motor, it will short and fry the climate control pushbutton unit, and you will be out another couple hundred bucks to get a defroster....

If you bypass it, you will get wide variations in cabin temp as the circulation at idle isn't that good, but that's better than full heat all the time from a blown PBCU or no heat at all!

Sadly, no one ever said these cars were cheap to maintain....

Peter

I fixed it by removing the pump and using gasket sealant all around the 2 mating surfaces.

Straightforward remove and replace.

It stopped leaking by tightening four screws. Thank you all.

newkid, it's fortunate that you were able to fix it simply w/ a screwdriver.