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bobo 03-09-2007 10:39 AM

pcv valve bad???

a friend of mine has a '96 jeep cherokee, with an inline 6cyl. he said that smoke was comming from under the hood, and when he checked it out, oil was seeping from the valve cover gasket. he removed the oil fill cap from the valve cover and there was quite a bit of air pressure built up in the engine. only thing i could think of is the pcv valve is clogged/stuck closed...anyone have any ideas????


slickshift 03-09-2007 12:55 PM

That part can be checked by removing it and shaking it
If the "valve" inside doesn't move back and forth, it's time for a new one

But a clogged one won't cause valve cover gasket leakage enough for oil to hit the exhaust manifold and create smoke
That means it's time for new valve cover gaskets

Or perhaps the covers just need a little tightening
Find the specs and use a torque wrench
Over-torquing can bend the covers causing a worse leak

bobo 03-09-2007 02:11 PM


im not conerned about the leakage from the valve cover. its the pressure that was released when the oil fill cap was removed. i told my friend to find the pcv valve and shake it, if it rattles its ok, if not replace it. but could a clogged pcv valve cause that much pressure in the crankcase???


P.S. it doesnt burn oil, and runs a good 35-40 oil pressure, so its not the rings or bearings

slickshift 03-09-2007 04:23 PM

It wouldn't help, no

But it may be normal for that engine to have enough pressure in there to blow out some oil splatter if the oil cap was removed while it's running

It's hard to say if it's excessive from here

bobo 03-10-2007 06:03 PM


my friend removed the pcv valve, and there was no more pres sure when he removed the oil fill cap. he is going to replace the pcv valve and valve cover gasket. ty for ur input...bob:thumbup:

slickshift 03-10-2007 07:59 PM

Thanks for the update
That would be normal to lose pressure w/o the valve
the valve requires a certain amount of pressure to open
We still don't know if the pressure is excessive or if the valve is clogged

IIRC the valve is an easy access and is inexpensive to replace
A new one would answer some questions

bobo 04-22-2007 01:15 AM


he replaced the pcv valve, valve/cam cover gasket, and all is well...bob:thumbup:

slickshift 04-22-2007 07:43 AM

Thanks for the update!

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