PCV Set up

Stock, no real need for anything else. On a 4.0, the front elbow needs to be free flowing and the rear elbow needs to have an orifice. If that is the case, and the hoses have no leaks, and engine is in good condition (minimal blowby), you won't have issues. No issues with mine whatsoever.

Sometimes the engines will puke oil onto the air filter, on a 4.0 this happens when the orifice elbow gets clogged. Pressure forces oil up the front elbow and down to the airbox.

On a 2.5, only one elbow is used, it's placed towards the rear, and it is hooked to the airbox. The line to the intake manifold is hooked to a threaded tube in the valve cover. When 2.5's puke oil onto the air filter, it is because the threaded tube got clogged and pressure forced oil up the rear elbow, and again, up and down into the air filter like a 4.0.

On my 2.5L I disassembled the valve cover to clean the internal vent tubes and PCV valve and fittings. I found a small brass orifice inside the cover that was completely sealed over with tar and gunk. No way could any air get through it.

It might be worth you while to do the same to ensure it works properly.

Like what flyer says, on my 91 that uses no oil, the brass fitting in the front of the VC has a fairly small passage thru it that does get plugged or restricted after time. I use a small drill bit the same OD size and gently clear it out by hand NO drill motor. Also dosent hurt to pull the small plastic line off and make sure its clear as well. A catch can and the like is a defeating the purpose of a pcv system as it will do nothing for venting the crank case. If you have that much blow by then there is other issues like rings. The plastic 90 off the top of the VC can be had from jeep parts suppliers if yours is broken. It will also come with a new rubber gasket.

BTW, there is no PCV at all on a 91+ fuel injected YJ. It is a Crankcase Ventilation (CCV system) and the elbows are CCV elbows. Since you have a 2.5, clean up the tube at the front of the valve cover, change the single elbow, and you should be good to go for a long time.

machoheadgames said:

BTW, there is no PCV at all on a 91+ fuel injected YJ. It is a Crankcase Ventilation (CCV system) and the elbows are CCV elbows. Since you have a 2.5, clean up the tube at the front of the valve cover, change the single elbow, and you should be good to go for a long time.

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Ah you're right. My jeep has had long term effects of my short term memory.

I had all my vacuum lines off during the rebuild and remember cleaning a suction valve but t it was the power brake booster check valve.

Bummer. Hopefully it's not an expensive fix. I'm sure you noticed a lot of fluid on the ground from the transfer case. Be sure to top it off when you get it back together.