Can anyone help describe where the pcv is or have a pic of where it is 1991 I6

 

on top of the engine is a plastic tube coming from the valve cover that is the pcv vavle

 

got two of those, toward front or rear?

 

the one towards the rear

 

Thanx

 

just to chime in, its been posted a lot, but they WILL break when you take them out. If you are really careful you might be able to salvage them. I too thought I was going to be different and get them out with no problems, and 10 min later I was driving to the parts store.
BN

 

Well this is a new to me Jeep, just picked up yesterday and my buddy that knows way more about cars than me want to check it but we could not figure out which one it was. Thanx for the info I will get one today before we mess with it.

 

The PCV valve is the one in the front. The one in the rear is the calibrated orifice where the air comes out from the crankcase.

 

I have an 89 and 94 I6 and neither one has a PCV. both have a metered vacuum on the back and a breather tube on the front

 

Ya, good call, I should have mentioned that too. Its a "PCV orfice," not a valve, as there is no valve inside there. Its just an orfice, or fancy speak for a small hole.
Ben

 

I changed them out on my 94 i had, and it caused my valve cover gasket to blow out and leak really bad. I was later told Its not a good idea to change them because that happens alot

 

Don't see how it could blow out valve cover gasket. Without vacuum at the rear metered port, the crankcase will just breath through the front breather tube and dip stick tube causing blow by and a oily air filter. but not build enough pressure to blow out gaskets. We used to run V8 powered race cars all the time without a PCV

 

If the PCV system isnt working the crankcase will be pressurized, and will cause leaks at all the gaskets.(Or the weakest one!). You need Vacuum on the crankcase at all times. The PCV valve is only to seperate the oil so it doesnt "Suck" oil.
If the engine has more Blowby than the PCV can handle then you will also have positive pressure in the crankcase...
This is one of the most important "Invisible" systems on the motor. Everyone overlooks it !

 

on the 4.0 its actually called a CCV system and not PCV b/c there isn't any valve involved. just a tidbit of info I thought yall might like to know

 

i thought PCV = Positive Crankcase Ventilation?