I have a 2011 Acura RDX with 385000km on it. When I remove the oil filler cap with engine running, the air blowing out the filler hole is substantial.

With engine running I unplugged the output side of the PCV and no air is coming out. Since the PCV looked original I replaced it. But STILL no air coming out of it. Why not? I tried revving engine up but no change, no air blowing out. (Good suction at intake port leading to PCV though)

This vehicle's PCV is metal and screws into the block (just above alternator). Does that mean the crankcase whole may be blocked with carbon and I should scrape it out with a screwdrive? Not sure what's wrong

1 Answer 1


If you're seeing fumes coming out through the filler cap, this is typically called blow by and has nothing to do with PCV function. It would mean the rings are worn out and combustion gasses are going past them and into the crankcase, then out through the filler cap when it's off. Only fix is either rebuild or replace the engine. With nearly 240k miles on it, this is very likely what you're seeing.

  • I had a feeling the cause was blow-by, and I'm hoping stuck rings might also cause this? I thought of pouring seafoam into each cylinder and leaving for a few days to see if that helps.
    – TSG
    Commented Mar 24 at 22:16
  • Also...wouldn't blow-by pressure the lower crankase too - and shouldn't that appear at the PCV port? (To allow return to the intake)? Not clear why the PCV isn't allowing this pressure to pass.
    – TSG
    Commented Mar 24 at 22:17
  • @TSG - I'm not going to say you're wrong in that the PCV isn't passing gas (sorry - had to go there). I'm suggesting you have way broader issues than the PCV. You might try using some SeaFoam to try and free up the rings, but I'm doubting that's really your issue. I'm thinking your engine is tired. Commented Mar 24 at 23:27

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .