Re: PCV gone bad?

I have heard that the manner in which a PCV valve on a turbocharged car operates is somewhat different than that of one on a normally aspirated car. I admittedly don't know if the model year of the vehicle in question could have a turbo and more specifically if yours does but this may effect the testing procedure to determine proper operation of said PCV valve. IIRC in the case of a turbocharged car the valve should allow ventilation of any positive pressure from the crankcase to the intake only when the engine is not in a boost condition. There seems to be a number of people here on the group that may be able to verify/clarify this for you as I'm a little rusty on the subject. Hopefully this too will change soon however. Who knows, maybe this doesn't even apply to your car.

HTH,

David Bickel

With turbo vs. non-turbo, the PCV plumbing may be a little different, but the design of the valve is the same - it's a simple check valve in either case.

Bill Putney (to reply by e-mail, replace the last letter of the alphabet in my address with "x")

The PCV valve is a $5 part you can replace in 5 minutes.

If you're concerned it may be defective, why not just replace it and see if the oil consumption disappears? It's probably not worth the time to clean it out, and if you haven't replaced it before it's probably due anyway.

-DanD

Thank you, that is a nice piece of information to know. I had heard from someone a number of years ago that there was a slight difference between the way the thing would work under the two different circumstances. I suppose that the only difference may be the pressure that is seen by the device.

David Bickel

Exactly. The intake actually gets pressurized under boost which doesn't happen without turbo. It's nice they figured out a relatively simple way to do it (a simple check valve rather than a microprocessor-controlled solenoid). 8^)

Bill Putney (to reply by e-mail, replace the last letter of the alphabet in my address with "x")

Not all PCV valves have springs - many are just a free-floating plunger.

I know that it is strongly felt on the older Subaru forums that many brands of aftermarket PCV valves are inferior (even the metal ones). If you take a look at the finish of the plunger seating surface, they sometimes are very rough and pitted - not good for sealing very well. This is another case in which the recommendation is to get the part from the dealer.

Also, to add to the discussion, you need to make sure the PCV hoses are not obstructed. One of my vheilces recently started using a lot of oil. I found that the main PCV hose was totally clogged even though the valve itself was OK - so a secondary vent hose that went to the intake plenum was getting all the pressure differential and passing oil into the intake. Cleaned out the hose, oil consumption dropped back down. Also check for split hoses.

Bill Putney (to reply by e-mail, replace the last letter of the alphabet in my address with "x")

For what it is worth...

I pulled the PCV and the check ball was loose. I went ahead and used some carb cleaner and cleaned it up good. That appears to have addressed the problem. I but 600 miles on the car this weekend and did not use any appreciable amount of oil.

The lesson here is keep the PCV clean.

Jack