I have a 1990 525i that had its head rebuilt with new rocker arms,
valve guides etc. this summer. It was losing antifreeze which we
traced to the two hoses that go to and from the engine back into the
throttle housing. (the hoses are probably 1/2" diameter) and the gasket
for the throttle housing. When we fixed these, we noticed that the
radiatior had some oil at the top of the overflow bottle on the side of
the radiatior. The mechanic theorized that there must be a leak from
the oil cooler lines going into the radiator because I don't have any
antifreeze in the oil, the engine isn't overheating and the radiatior
blow-out plug is intact, so no extra pressure from the engine into the
cooling system, and no white smoke upon startup or any other time.
He thinks this is left over stuff from the summer's debacle and we just
didn't flush it out of the engine. But just to be on the safe side, we
replaced the radiatior along with the hoses. Bled the system as best
as we could (does anyone have a foolproof system for doing this?) and
we still get some oil at the top of the overflow bottle. Where could
this be coming from?
He wants to retorque the head just as a precaution, as we did not
retorque it after the head installation. What do you think of this
idea and do you have any specs for the retorquing?
Thanks for reading this lengthy post.