got a big issue with the missus bmw 318 is the engines building up silly pressure as in when running im struggling to get the oil cap off its sucking it back on and when i turn the shed off its hissing as the pressure releases any ideas i think its shagged

 

ive never come accross this before ive known of engines blowing caps off but never sucking them on has anyone got an idea

 

up

 

where abouts are you?

 

we've got a problem with one of the latest Vauxhall petrol engine's doing this due to a faulty one way valve in the cam cover that connects via a pipe to the inlet plenum. The vacuum is strong enuff to suck the engine oil up into the inlet and create a Batman style smoke screen....plus you are totaly unable to remove the oil filler with engine running. Dunno if a old BM has a similer one way vacuum valve set up?