PCV valve - how often to replace, how can you tell if bad?

Discussion in 'Fox 5.0 Mustang Tech' started by bloopbloob, Apr 2, 2008.

  1. like the title, how do you know when your PCV valve is done? i'm trying to find a mysterious oil leak, no luck, but its coming from the pcv area/(back of the engine where i can't see much....) so i pulled it out but didn't even know what to look for... but it looked fine to me.... replaced it last year...
  2. Service Manual calls to replace at minimum every 60,000 miles. The wire/mesh filter directly underneath the PCV Valve, which helps minimize the amount of oil that is introduced to the intake manifold, should be replaced every 30,000 miles.

    To test the PCV Valve, remove it from the plastic grommet in the lower intake. Shake the PCV valve, if it rattles, it's most likely fine. If it doesn't rattle, the valve is sticking and needs to be replaced.
  3. ok mine well mine rattles and looks clean, and just fine.... so how can the pcv cause an oil leak back there? cuz thats what everyone said to look at for my source..... ? but everything seems ok with it and the hose....?
  4. If it's leaking near the back of the lower intake, it's probably leaking between the block and manifold. If the PCV is sticking, you'll typically end up with oil in your upper plenum before you'll have a leak.
  5. And a bad PCV valve or excessive clogging in the circuit can cause oil leaks elsewhere, though the underlying cause is the blocked PCV pathway (the crankcase vapors start finding a new path of least resistance).

    I like to see folks check the plunger resistance in the PCV valve itself. The valve has a spring in it - if the spring broke, the valve would still rattle but the valve would not be considered servicable.