I have a bit of a stumper that I have not seen before. I have coolant in my reservoir that looks a bit like foam from dishwashing liquid. This is a 1990 760 turbo wagon with 240K.

My first thought was a blown head gasket, but I have none of the normal symptoms. There are no signs of coolant in the oil, no signs of oil in thecoolant, no signs of coolant around the head gasket and none of the sparkplugs look steam-cleaned. I have not done a hydrocarbon test on the coolant yet because my strips were contaminated. Compression was even across the cylinders when I had my post-purchase inspection 14 months ago.

The car has mysteriously lost about a gal of coolant over the 14 months that I have owned it. The radiator was new when the car got repo'ed (date of the receipt was 6/2003 and the paper tag on the rad has a manufacture date of 2002).

My thoughts are leaning toward some sort of leaking seal in the turbo (Mitsubishi). Would this make any sense? Not knowing the architecture of the cooling passages in the turbo I am thinking that some pressurized air could be leaking past the seal causing the foaming and some coolant could be sucked into the intake under vac.

Any suggestions are welcome.

Thanks,

Onkel Udo