How to know if PCV valve is broken/clogged

[Noobie]

A few years ago i had a rough idling issue with the E39 M54 (6 Cylinder N/A) and i remember that one of the methods used to diagnose if the PCV was broken (Apart from disassembling it) was to pull the oil fill cap with the engine idling and if there was an insane vacuum holding the oil fill cap then the PCV valve probably had a problem.
So my question is, is that the same with other engines? (Diesel Toyota and Gasoline 4 cyl N/A Kia)

 

[CR94]

That method might detect plugged (or misassembled) fresh air intake to the pcv system, or a stuck-open pcv valve, but not other potential problems.

 

[Silk]

Certainly not on a diesel, they don't have PCV.

 

[Linctex]

Originally Posted by Noobie
A few years ago i had a rough idling issue with the E39 M54 (6 Cylinder N/A) and i remember that one of the methods used to diagnose if the PCV was broken (Apart from disassembling it) was to pull the oil fill cap with the engine idling and if there was an insane vacuum holding the oil fill cap then the PCV valve probably had a problem.


No, this only occurs if the fresh air supply hose from the air inlet / air filter to the crankcase (usually at the valve cover) becomes clogged or collapses.

 

[Donald]

Originally Posted by Noobie
A few years ago i had a rough idling issue with the E39 M54 (6 Cylinder N/A) and i remember that one of the methods used to diagnose if the PCV was broken (Apart from disassembling it) was to pull the oil fill cap with the engine idling and if there was an insane vacuum holding the oil fill cap then the PCV valve probably had a problem.
So my question is, is that the same with other engines? (Diesel Toyota and Gasoline 4 cyl N/A Kia)


Its a one way air valve. Try cleaning the area your lips will touch then blowing and sucking in air.

 

[Virtus_Probi]

Originally Posted by Donald
Originally Posted by Noobie
A few years ago i had a rough idling issue with the E39 M54 (6 Cylinder N/A) and i remember that one of the methods used to diagnose if the PCV was broken (Apart from disassembling it) was to pull the oil fill cap with the engine idling and if there was an insane vacuum holding the oil fill cap then the PCV valve probably had a problem.
So my question is, is that the same with other engines? (Diesel Toyota and Gasoline 4 cyl N/A Kia)

Its a one way air valve. Try cleaning the area your lips will touch then blowing and sucking in air.

I would sell the car before doing this!!

 

[ARCOgraphite]

Hey this is an "oil lovers" forum!
We may have to question your commitment ....

 

[Mad_Hatter]

Buy a new one, they're not that expensive.

Otherwise, at warm idle you can pinch the hose between the valve and the intake and you should hear the plunger click. If you don't, there's a problem. If it's easy to get to, just take it off and see if it rattles freely - it should. If it doesn't, you have a problem.

 

[Yah-Tah-Hey]

Remove it and inspect. Pintel should move freely when shaken.

 

[CR94]

Originally Posted by Virtus_Probi
Originally Posted by Donald
... Try cleaning the area your lips will touch then blowing and sucking in air.
... I would sell the car before doing this!!
Then try blowing into one end, then blowing into the other end---as Toyota recommends.