Expert: Sean Halliday - 2/26/2008

Question
Hi, My 1995 318i runs very rough at idle. And there's a  whistling sound coming from engine (think its sumwhere in the intake manifold but I could be wrong).

Idling & oil cap removed => intakes air through the oil cap & dipstick.  What & where could be the problem?

Thanks

Answer
A leak at the intake manifold is the likely problem.Whistling is air being drawn in through the gasket and will make the idle,fuel air mix totally off.Hence the bad idle.Check all vacuum hoses also and especially the one under the intake,its real hard to get to so you may need to remove the intake anyway to get at it,so replace the gasket at the same time.