I have a 300D Turbo with about 180,000 miles and I have determined that oil is passing from the valve cover to the air filter through the tube that conects them both. Why? Is it blow-by in the valves or the the piston rings? Please advise. If you want me to call you to talk me though it send me your number.

 

TODD ARE YOU SURE ITS COMING FROM THE VALVE COVER BREATHER OR IS IT COMING FROM THE SEAL LEAKING ON THE TURBO AND ITS SPRAYING IT BACK INTO THE AIR CLEANER ASSEMBLY AT IDLE TIME I HAVE SEEN THIS HAPPEN AND A TURBO OVERHAUL SOLVES IT AS FAR AS COMING FROM THE VALVE COVER SOME HAD SMALL BREATHER HOLES IN THE COVER NEAR THE BACK AND THEY GET CLOGGED

 

I am pretty sure it is coming from the tube running from the valve cover to the intake. I will check it out.

Normal Operation? If you ask do irun it under normal operation? Yes, every now and then i kickin the turbo. But i run it about 10 miles to and 10 backto and from work, five days a week.

I will try to change out the valve cover gasket this week-end as i have one already. Ialso loosened the oil filler cap and checkedthe pressure.The capalmost jumps all the way off.Do i need toreplace the rings? I will have to get my wagon on the roadto breakthe sedan down and replce therings. A good charge on the battery and repair the hydline leak and she will be running again.

 

That is called "sump compression" blow by or what ever, if there is some smoke comming out of your oil filler cap, then it is time for new rings...

 

I love the cap lock pix

 

A plugged Air Filter can cause you to pull in more oil vapor than it normally would as the air will take the path of least resistance. How about a "tune up"-adjust the valves and injection pump timing so that things are happening when they are supposed to.
Besides piston rings worn exhaust valve guides/valve stemscan increase your blowby.