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CRANKCASE VENTILATION SYSTEM

All 2.5L 4–cylinder and 4.0L 6–cylinder engines
are equipped with a Crankcase Ventilation (CCV)
system (Fig. 5) or (Fig. 6). The CCV system performs
the same function as a conventional PCV system, but

does not use a vacuum controlled valve.

 

http://jeep.off-road.com/jeep/articl....jsp?id=257985
The Jeep does have a PCV Valve and I suggest reading the above link to find out about it.
It is attached to the valve pan on the inside and is only replaceable by replacing the whole pan...but this will be explained in the above link. If your throwing out oil...you should read, this could cause other problems as well with the vehicle running bad. Let me know if this helps.
Billy

 

No.

No PCV valve.

You dont need to replace the whole "pan," or valve cover as its actually called. That link completely debunks what you posted. 5-90 and whowey's posts put together are all you need to know. Take the valve cover off and clean it up, get new breathers from the dealer and youre good to go, unless youre like me and your oil control rings are bad.

Why do people on this forum CONSTANTLY throw out incorrect information and say its proven fact? Even in this very thread where the correct answer was already told, and expanded upon, you post wrong information, and provide a link that DISPROVES what you have written.

Its beyond me.

 

whats to confuse about it...also says this was a problem...and should be changed between 30k and 50k miles....sounds like someone needs glasses..lol so they can read.

 

This is the quote from the link...
"I say breather because the PCV valve is built into the valve cover."

I suppose you didnt read that part and then attacked me because I did.
Hmmm...read just a little bit better.

 

Theres about 20 different opinions on this page. Only 1 is correct. Are you sure its yours?? Just because its on the internet, doesn't mean its true. BTW the link you provided says that the 4.0 has a CCV and PVC. Which one is it?

 

if we are on the subject of reading further it also stated that

Models Affected: 1987-1990 Jeep Cherokee/Comanche

so I would do a little more research for other models.

 

well imma go ahead and order it for my 87 xj its only $20 for the tubing and valve....

 

Its the rear valve on the valve cover. The front one is your ccv. Just repalced mine. was causing me to stall every time i stopped if i didn't leave my foot on the gas. then a week later my upstream O2 went hahaha

 

It a bit of a pain but how i did it worked. I took some pliers and broke it down so that it was even with the grommet. i pulled the grommet out and then took out what remained of the valve. I stuck the grommet back in then stuck the new Pcv valve in. You might want to take the valve cover off but you dont need to

 

That is quite an entertaining thread. My Haynes manual states that the later models have the CCV system which is basically a hose that goes into a rubber grommet on the valve cover. Seeing how yours is a 1990 it should have a pcv valve which is set on the rear of the valve cover, with a hose connected to it (which should have vacuum in it), the valve will twist right out, very simple, I just cleaned mine a couple weeks ago, you can buy a new one for about 10$ at Autozone. Another part of testing the valve, aside from checking for vacumm is to take it off and shake it, it should rattle inside, if not it is bad.

I JUST POSTED THIS ON THE WRONG THREAD LIKE A TARD, BUT IT'S STILL VALID TO THE DEBATE......

 

The books are wrong just call Ma Mopar they will tell you it is really the CCV system.

 

The Jeep dealer parts catalog calls it an oriface, not a PCV valve. I just did my rounds with mine when I replaced my valve cover gasket on my GC.

 

well I was thinking the elbows that go into the VC could just be empty pieces of plastic and not actual pcv valves like my 86 olds had, but still....they do call it a pcv valve.....

 

"They" do, but Jeep does not.