Hey there,

This problem regards a 1990 760 turbo. I just bought the car and have no idea about its history. Has 115K on it, runs great. Turbo a bit smokey.

Anyway, It seems that I have a thin layer of oil in my radiator expansion tank. I also have water vapor condensing on the top of the dipstick causing it to rust and crud up. The oil is not milky and looks very good. It has also exhibited white cheesey stuff (a.k.a. mayonaise) on the underside of the oil cap. They mayonaise council may have a problem with this description, though.

I have read quite a bit about oil and coolant leaks here (radiator/transmission leaks, head gaskets, etc). Pretty informative stuff. Great page!

Since this is a turbo (mitsubishi td-04), I was wondering if it is likely that the turbo cartridge has a crack in it. The proximity of oil and coolant is very tight here. I am sure this it is theoretically possible, but how often do you guys see this? Also, what is the likelyhood of a cracked head or block, causing this?

I am hoping for a head-gasket problem (how often does one wish for this?). I have installed a reworked head in half a day- not really that bad. Hopefully this will translate in to an opportunity to have a valve job. Trying to look on the bright side here!

Any one have any ideas about the cause or how to diagnose the source?

Thanks in advance,