Crank Case Vent issues

Hello all, first post. I just got my first XJ, 1992 4.0 4x4. Overall its in good shape, I'm just going through it fixing little stuff, using the Chilton manual as a guide. The rear valve cover grommet now has a silver(aftermarket) breather cap on it, the front fitting looks like it is connected to where the rear should be, (into the intake manifold perhaps), and the tube where the front fitting SHOULD connect to the airbox is taped off.
There is a significant amount of oil all over the valve cover and top of the engine, possibly from the front grommet, which is badly deteriorated and cracked. My plan was to replace the front fitting, leaving everything connected as-is, degrease the engine to determine the source of the leak, and go from there, but as soon as I started messing with the fitting it broke in a couple places. I don't even want to degrease the engine and risk getting anything into the valve cover, and I want this thing to run right, so I'm hoping for some help on how to get everything replaced and connected properly.
I was planning on taking the grommet and fitting off to take to the parts store to get replacements, but it was only coming off in pieces. The manual didn't provide much guidance in HOW to remove anything...is there any special technique to removing whats left of the grommet and fitting? Do I have to pull the valve cover? Can I get replacement parts at a parts store, or do I have to go to a dealer?

Check with Napa. I think they've got it all.

The vac lines come in three sets.

The line from the valve cover FRONT grommet (grommet included).
Goes from the front of valve cover to intake.

The continuation of that line (the other half). Also comes with fuel pressure regulator hose.

...and the grommet (metered orifice) to the rear of the valve cover and hose to the front of the intake manifold.

I think I paid a total of 35-40 bucks at NAPA for all three. Removing and cleaning the valve cover and the baffles at each end and having the correct and clear vac lines should fix your problem.





EDIT: These are the RENIX vac lines. Should be similar.

I've seen some real Einstien (sarcastic) logic to mods to the vac system to correct blow-by, but in my experience, having all the right parts, hooked up the right way, actually works.

One correction of above: on the 95 and 99, at least, the vacuum line from rear of valve cover goes to the nipple on the manifold just aft of the throttle body.

The difference between working and not working in this system is fairly small, and I think some people, rather than fixing it right, figure it should be modified. I found that if the parts are all good and not clogged, it will work as designed, even in an old engine with a fair amount of blowby.

The earlier Renix engines were pretty notorious for blowby, the later HO less so. There was a vacuum line update made for the Renix, in which the elbows were changed from sharp corners to gentle curves. That alone made a critical difference in my 87, and it stopped oiling up the air cleaner. Later models have a larger diameter line with fewer sharp turns.

Matthew Currie said:

One correction of above: on the 95 and 99, at least, the vacuum line from rear of valve cover goes to the nipple on the manifold just aft of the throttle body.

Click to expand...

Correction noted and checked...you are correct. Same, same on the RENIX.

Thanks for the info, I'll give it a shot. There's no Napa listed where I live (Yuma, AZ) so I'll check where I work(El Centro, CA) but I'm not overly hopeful that they'll have the parts in stock in a towm this small...is there another store that would carry them? Also, the grommet feels more like plastic than rubber-I'm guessing it has been overcooked. Is there a trick to getting the old one out, or do I just break it apart? Then does a new one go in pretty easy, or is there a trick to it?

Just from memory, but I think yours go in and turn a little to lock.

This is the front without the orifice, but I believe they lock in the same:


Good luck.

joe_peters said:

Just from memory, but I think yours go in and turn a little to lock.

This is the front without the orifice, but I believe they lock in the same:

Good luck.

Click to expand...

If it's the original valve cover and CCV parts from 1992, it might be. Then again, it might not.

My '92 has the later fittings that just snap into the grommets. I had a valve cover leak develop that was discovered during an oil change at the local dealer almost 10 years ago. Apparently, Chrysler didn't sell the gasket alone, you had to buy a whole new cover to go with it, so that's what was done. I ended up with a cast valve cover with the baffle plate in it (not the two tubes like some pics show of older models), the later CCV grommets and elbows, and the original 92-style oil cap (put on and twist 1/4 turn to lock into place. After 18 years, I wouldn't rule out the possibility of the same thing happening to Johnny.

The grommets will come out easier if you can get the elbows out first - try twisting and pulling first. If it's like the picture above, some degree of twist will allow it to come out. If it's like mine, that won't work and you'll just have to wiggle the thing out. Once the elbow's out, just use a flat screwdriver to pry the grommet out of the valve cover. Be patient, but expect to apply some force - they fit pretty snug.

Grommets bought at the dealer will have a part number molded into them, but I don't recall on the elbows themselves (though I would expect it to come up on the same "page" in the "catalog").


Rob