I have a 2012 MCS Countryman, which has the N18 engine. I have replaced the integrated PCV valve diaphragm twice, after the original diaphragm started leaking oil due to a tear. The issue I am having is that the the valve is still leaking fumes that smell very strongly of gas, which end up getting sucked into the fresh air intake of the climate control system. I simply used my nose to trace down the source to the PCV valve. The valve is no leaking any oil, only the fumes. I replaced the diaphragm a second time, and the issue started again almost immediately. The diaphragm cover does not seem to be loose, and appears to be fully snapped into place.

Has anyone experienced the same issue with the PCV valve leaking fumes that get into the cabin via the climate control fresh air intake?

It occurred to me that perhaps the apparent malfunction of the PCV valve may be related to some other problem in the PCV system, so I wanted to check the functioning of the other components of the system. The N18 has a PCV vent hose that runs from the crankcase to the the engine air intake duct, connecting to the duct on the drivers side of the duct. I thought perhaps there was a clog somewhere between the duct and the crankcase. I assumed that the air would flow from the crankcase into the intake, but this does not appear to be the case. I hooked up a vacuum/pressure gauge to the both the hose and the connection to the intake. What I found was that there is a slight vacuum coming from the hose, and there is no pressure or vacuum at the intake connection, which was puzzling, as I assumed there would be a very strong vacuum in the air intake. Even more puzzling is that if I hook up a hose to the intake connection, it passes air in both directions (I can suck on the hose or blow on the hose, with no restriction of airflow in either direction). If I just leave the connection unblocked with the engine running, the engine runs normally, with no air being sucked through the unblocked connection.

Can anyone tell me if this is normal, and what the function of this part of the PCV system is? Because there is a vacuum coming from the PCV vent hose, I figured that the air intake simply acts a source of "metered" air for the PCV system, since the connection is after the MAF; however, I don't understand how, if air can flow either direction through the air intake connector, there is not a massive vacuum pulling air the other way, into to the air intake.

I would greatly appreciate any help or insight the community can provide.

 

How did this all end up? I’ve got a similar issue.

 

Hmmmm, there's no "gas" in the PVC system as these are direct injection engines.

Are you smelling oil or gas?

 

Blow-by that the PCV system is scavenging is air/fuel mix that makes it past the rings and into the crankcase, where it must be separated (along with oil particles), so there are definitely times your nose can pick up the smell of fuel.
If you have tried to repair the integrated PCV, and it's not workingworkimight be worth a while new valve cover. I'm about to go that route while doing a chain set, FWIW. Not a cheap answer, but repeating a repair that didn't last isn't money well spent either.
will try to update how this one turns out.