Another PCV Valve Question

Topic: Another PCV Valve Question (Read 2318 times) previous topic - next topic

Another PCV Valve Question

October 23, 2004, 11:15:19 PM

So today I finally found the blasted PCV Valve and changed it out. But in the process i noticed a couple things and have a couple questions.
1: What exactly is the purpose of the valve and how does it work? 2: Is it supposed to expell oil or be covered in it when you replace it? 3: If it is/isn't/indifferent is it possible for it to create a significant/noticable leak. And 4: Is there anything that I should be looking out for after the fact now that i've changed it. And yes i realize there was another thread on this, but it was kinda going off on a tangent!!! Anywho any insight on this would be appreciated. Thanks!

Re: Another PCV Valve Question

Reply #1 – October 24, 2004, 12:14:22 AM

1: the PCV allows the crankcase to expel excess pressure (pulsations) caused mostly by the internal movements of the engine while not allowing the negative pulses to suck air into the crankcase. Essentially, it is a check valve.
2: Yes, it will expel oil vapors. The hose connects the PCV to the intake manifold (negative pressure) where the vapors are burnt by the engine.
3: Yes. If your engine has worn rings it will have excessive blow-by. Pressure form the cylinders will pass by the rings, into the crankcase and out the PCV carrying with it extra oil vapors. But there will be no liquid oil flow from here - as in a gushing oil leak.
Also, check that the rubber grommet the PCV fits into is OK. (it just pulls out) If your spark plugs are oil fouled or you have low compression, engine wear could be your problem but if your PCV is properly seated and your hose is good there should be no mess.
4:Clean the area thoroughly with degreaser, then drive it. If the oil comes back, double check your PCV system for a good seal,clean it again and check your rear lower intake gasket. The old stock 5.0 in my XR-7 had a bad seal when i bought it that leaked like a sieve and caused the engine to smoke horribly from the rear of the block. I ffirst thought it was the PCV. Bigger job but still not to expensive to D-I-Y.

Re: Another PCV Valve Question

Reply #2 – October 24, 2004, 12:17:48 AM

Oh - yeah , if you run a supercharger your PCV should vent between the outlet of the mass air and the inlet of the blower (negative pressure)

Re: Another PCV Valve Question

Reply #3 – October 24, 2004, 01:09:27 AM

I'm in the process of fixing such a leak on my Grand Marquis and I'm gonna have to replace the PCV filter and screen as well, it seems. Anyone had any success finding these at retail parts stores?

Re: Another PCV Valve Question

Reply #4 – October 24, 2004, 01:13:01 PM

Quote from: Ifixyawata

Anyone had any success finding these at retail parts stores?

At my local Auto Zones they are on one of those four-sided self-standing racks (i'm sure there's a name for these things..... :wtf: ) Anyways, it's full of small Purolator parts, PCV valves, fuel filters, all that tune-up goodness. Hope this helps.