Bmw 316 e46 - Oil leaking from oil cap - allan doc

I have bought 3 new oil caps for my e46 316 bmw and after a few months each start to leak again. When i remove the cap there is positive pressure coming from from filler hole. Is this a common problem with these cars? There is also an oil leak around the dipstick or sump. It difficult to tell. Could a knackered ccv cause this? Is there any checks to prove this? Thanks

Bmw 316 e46 - Oil leaking from oil cap - RT

Sounds like it's got a blockage in the Crankcase Ventilation System - or the piston rings have gone - the +ve pressure is from piston blow-by gases which are normal in slight amounts.

A compression test will tell you the state of the piston seal and you'll need to check/clean the PCV hoses between the engine and inlet manifold.

Bmw 316 e46 - Oil leaking from oil cap - allan doc

Thanks. Car has only done 75000 and been well looked after so hoping it not the piston rings.

 

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