Just got a 98 S70 turbo with 76,000 miles. When driving a bit on the aggressive side, I get oil being forced past the oil filler cap. It by passes the oil filler cap and collects under the spark plug cover. Any ideas on where to look for the problem. Put a new gasket on the cap, but it still leaks. thanks Ron

 

More then likely Ron, you have a clogged up PCV system. The pressure in the crankcase is not being relieved through the PCV and is now forcing it's way out of you car through the filler cap. I would not try to seal it up until you have the PCV looked at. Otherwise you could blow something else out, like a RMS.

 

+1 on the PCV system.

if it is working fine and no clogged hoses, then get a catch can.

 

I had the same problem, it means that it is the PCV system. I assume you are having smoke coming out of the dip stick tube as well? Do the PCV system and clean the PTC system, then run it for a while and if your still having the problem, do a compression test and that will tell you if your problem is running a little deeper than just a PCV system.

 

Hey !! thanks for the info on checking out the PCV system. Based on other threads on the Forum, it sounded like that was the thing to look at next. So I'm off to get my hands a bit dirty. Thanks again. Ron

 

On my 98 S70 it turned out to be the oil cap gasket. The thing was as hard as steel by the time I replaced it. It's probably the crankcase ventilation as others have mentioned, but you might want to replace the 50 cent gasket as well.

 

If cleaning out your PCV system doesn't solve the problem you may want to look at your turbo or the valve stem seals. Both can cause backpressure buildup and cause blowback in the crankcase.