Crankcase pressure

[Martymartino]

I have a 2003-2004 m-9000 which is blowing oil out of the lower filler cap hole or dip stick hole if you open either. I have done a compression test, which checked out within specs. Also checked the vent valve on top of the valve cover which seems okay. Where are there any other vent valves which could be dirty or stuck. Any other ideas would be appreciated.

 

[jaxs]

This isn't from inadequate ventilation, the problem lies with unusual crankcase pressure. Since you've eliminated piston blowby, I'd look toward exhaust valve seals then oil circuit in turbo. Disconnect hose bringing exhaust to turbo to see if there's change.