Can anyone definitively tell me the purpose of the crankcase vent hose on >2011 N18 engines? This is the skinny hose that comes up from the back of the engine and and attaches to a port on the driver's side of the air intake duct. I'm trying to figure out which way air should be flowing - out of the hose, or into the hose.

Interestingly, the N18 engine prior to 2012 does not have this hose.

The PCV system on my 2012 Countryman S doesn't seem to be working right, so I am trying to diagnose it.

Thank you!

 

There should be a slight vacuum in the turbo inlet pipe, which would cause that small tube to be flowing from the crank case to the turbo inlet. However, the main PCV hose is the larger tube running to the cam cover. If you are having issues with the PCV system, chances are better it is related to the baffles and valve inside the cam cover.

 

Nik,

Thanks for the input. According to my vacuum gauge, I have atmospheric pressure (0 on the gauge) from the fitting on the turbo inlet pipe, and a slight vacuum on the crankcase vent pipe, the opposite of what I was expecting. I found that I can blow air into or suck it out of the fitting on the turbo inlet pipe (through a hose), so it is not as if it is blocked or has a check valve on it, so the lack of vacuum there is puzzling.

I have replaced the PCV "valve" diaphragm in the valve cover twice, but it is still leaking vapors (strong gas/oil odor, but not actual oil) that find their way into the cabin through the climate control system. I was therefore trying to determine if there was trouble elsewhere.

I don't understand the lack of vacuum from the turbo inlet pipe. Anyone have any theories?


-------------------------
Patrick
'12 Countryman S All4

 

Is this with the tube connected and the car running?

 

The car was running. The PCV tube was disconnected, and then pressure from the tube was measured (slight vacuum), as well as the pressure at the hose fitting on the inlet pipe (atmospheric or 0 gauge pressure). I even revved the engine up to about 3,000 rpm, which had no effect on the turbo inlet pipe pressure.