This may seem like a dumb question, but I have to ask. I changed the water pump and thermostat plus flushed the cooling system in my girlfriend’s 300 diesel (turbo engine with 200K on it) a month ago. It now shows just the very smallest wisp of oil in the expansion tank. There is probably less than one drop worth of it in there, and it is definitely oil NOT transmission fluid. (I blotted some up with a paper towel and it is not red.)

I know what this means: head gasket time. But there is no coolant in the oil, in fact the cooling system holds pressure in it overnight (strange?). There is no coolant in the transmission fluid either. In fact, there is no coolant loss at all. The car does run warm, about 95-100 degrees in hot weather with the air conditioning on.

But I was wondering if there is ANY chance at all that re-torqueing the head bolts might even have ANY chance at sealing it back up? Is it worth trying, or do I even have to worry about this small of an amount of oil? I hear about diesel’s leaking, but I always assumed that means external, not internal leakage.

Thanks for the help everyone!

Greetings 450,

Is the oil that appears in the overflow tank consistant? What I mean by thatis, does it reappear after either flushing the tank or blotting it all out? I'd fully flush the tank and try this one over again. The next thing is that seeing as you have good coolant pressure, maybe to much from what you say, could be a stuck thermostat at those constant temp readings. If it were me I'd check the following items. First blot the paper towel into the oil in the coolant tank, and let it sit till the coolant has dried and only the oil remains. Does it smell like tranny fluid then? If it does, then you probably have a radiator leakage from the tranny fluid line internally, which is a better case senerial. If you are convinced that the oil on the paper towel is engine oil then drain the engine oil into a clean pan and visually inspect it for the coolant which should be quite evident. Pulling the dipstick won't tell you the story unless you have a massive leak of antifreeze into the engine. Coolant pressure is higher than oil pressure thus you should have coolant flowing into the lubrication system until the coolant cools down where by leaks only through cracks in the block would allow oil into the cooling system. A leaking tranny line that goes through the radiator would be my first guess culprit if I were guessing blindly.

Charles

Here is an update. I decided to go for broke and retorque them since I would have to pull the head anyways. I have not seen any more oil in the coolant, just a little left over stuff floating around. I don’t know how long it will hold, but I have my fingers crossed. I will keep you posted!