where is the pcv valve?

[choppedzj]

i have an 87 4.0 mj and i haven't the slightest clue where the pcv valve goes. Any help would be greatly appreciated.
brad

 

[jneary]

there is no pcv valve. the rubber grommet in the back of the valve cover is the pcv system, although you do need to make sore the grommet isnt blocked. there should be a small hole underneath.

 

[jneary]

i didnt realize you haa 94 until i read your profile, the pcv valve is the gray fitting at the rear of the valve cover. it has a small restriction in it so it doesnt suck too much oil out of the engine, still make sure it isnt plugged up.

 

[Matthew Currie]

It's common, especially on the early 4.0's like your 87, for the crankcase vent system to misbehave, create a lot of blowby, and foul the air cleaner. You may never solve the problem completely, but it can be kept under control. It's important to keep the vacuum tube clean and clear so that it pulls a vacuum and doesn't allow the blowby to push vapor out the larger front hose, which is supposed to be the inlet. At some point the tube itself was subtly updated, with gentler curves in the fittings, which seems to help, so if you're having trouble it might be worthwhile to bite the bullet and buy the new tube from Jeep. You should also clean it out occasionally, because it does get restricted by oily sludge.

 

[choppedzj]

thanks for the info guys. It alleviated some guess work.
brad