T6 PCV system

[monty400k]

I'm having a bit of a nightmare with the oil box/PCV system on my 2010 T6, bought the car around a month ago and noticed what I initially thought was a bad pulley noise coming from the engine when warm, from some investigation I worked out that it was air being drawn past the seals as the crank case was pressuring, the dipstick and oil cap are both hard to remove with the engine running as they are under pressure.

Found several threads online from people with the same issues, and sure enough the diaphram on the oil box on top of the engine had torn. Rather than replace the whole oil box I bought a replacement cap and diaphragm from ebay which seems to cure this issue for most people however I can't get the cap to seal properly, crankcase is still pressuring and I'm getting an intermittent mooing noise from the valve as air is drawn past the diaphragm, which is causing the idle to fluctuate.

I can't buy just the cap and diaphram from Volvo, only the whole oil box, the replacement aftermarket cap is poor quality (it's not perfectly round) should I take a punt on another aftermarket cap or stump up for a complete genuine oil box, my car has 180k on it and it's still fitted with the date stamped original.

[GrahamBrown1]

I’d just fit the genuine item and be done with. Sounds like a lot of messing about. You probably could have sorted it by now or by the time another eBay special arrives. I’m not sure how access is but if it’s difficult I certainly wouldn’t want to be having to do it twice or more.