Can anyone help me here. In October 2008, I heard my belt squeeling, looked into the engine compartment, and found water-pump leaking at the bearings. I replaced the pump and fan belt, but also made absolutely sure the motor never ran hotter than normal. Then in late November, during a routine water check, I found oil in the cooling system bottle - immediately ran the car to a shop to investigate. After checking radiator and oil cooler, we found a faulty oil cooler. Replaced it, and all was fine - that is until last week - and found oil back in the cooling system. There is no water in the oil. I have replaced the oil cooler again, but there is still oil in the cooling system. I am fanatical about temperatures and overheating, and can vouch that the car has NEVER run hot. Is there any other way oil can get into the system? I have verified that it is engine oil, and not tranny fluid.
thanks
Rainer

I think that once oil gets in the cooling system, it is difficult to get out in one shot. You will probably want to use an Alkaline cleaner, like Disodium trioxosilicate, pentahydrate. Part number is 001 986 21 71 (500 grams). May take more than one treatment?

Once you've used the cleaner, then you might want to use a Citric Acid flush at 100 grams per liter. Part number is 000 989 10 25 (500 grams).

I think it is also recommended that the coolant over flow tank be replaced. I'm not sure that you can really get it clean, but maybe so.

If the oil is left in the system too long, it will degrade all of the rubber hoses and they will have to be replaced.

Good luck!

__________________
Steve

1992 300CE Sportline Sophie
1990 300E Emma - in the family
1979 240D Josephine - sold, but not forgotten
2004 Pacifica AWD

http://web.mac.com/dakota/Mercedes/Home.html

Are you noticing any oil loss? If so, you have another leak - probably the head gasket.

If you aren't losing any oil, chances are there was some residual oil in there that never got flushed out. Getting foreign crud out of a cooling system is a royal PITA.

I have an old '78 Volare that the PO decided to put stop leak in. Well, I replaced the radiator, the hoses, etc., and flushed the whole thing for no less than 30 minutes with a garden hose and the motor running.

4 years later, two coolant changes later, I still see that crud when I take my cap off. And that's on a car with a dirt simple cooling system.

-tp