M111 W124 E220 oil in coolant

[Sam Skelton]

Hi all,

Just bought myself an E220 Coupe from a mate - and I've discovered oil in the header tank. There is no mayo, nor froth, either in the oil cap or on the dipstick. The heater isn't hot, and the water temperature isn't increasing significantly. The header tank doesn't appear to be pressurising even to the expected level.

The car is running fine despite this. The amount of oil in the tank doesn't appear to increase with revs, only with time. I've been trying to clear it as I go with some degree of success.

The chap my mate bought it from (He only had it a couple of months - a fellow journalist who bought it for a feature) wasn't a car person, and it is more than possible he topped the oil up into the wrong hole. I can't rule out something so stupid yet.

Instinct is telling me it probably isn't the head gasket, it's possible that it could be the oil cooler - are there any possibilities I've missed, or any tests I can do to narrow it down?

 

[LostKiwi]

If its the oil cooler i will probably leak coolant into the oil too (once the engine shuts down there is more pressure on the coolant side than the oil side so if the leak is bad enough it will leak back - not guaranteed but likely).
It is possible to be the headgasket - the oil gallery in the head goes close to a waterway.

I'd flush the coolant system thoroughly and monitor it.