Valve Cover Bolt Size

[KMAPRO]

OK, I am headed out tomorrow to pick up a valve cover from a 96 Cherokee to go on my 87 Comanche. Anybody know, off the top of their head, what size socket I need to take with me? I just don't want to have to fool around in the dark looking at mine tonight...

 

At least, I am hoping to go get one. The local Pull-A-Part has 2 96 Cherokees on their lot. They do not list whether or not they still have the valve covers on them though.

 

Also, I have located a 98 4.0 valve cover as well. Will this work on my 87 4.0?

[HellCreek]

I have a 2.5L and it takes an 11 mm. I just tightened them yesterday.

 

-Tom

[maddzz1]

You need to use the newer style gasket with it and reroute/plug some of the vacuum lines. mjeff87 did this, I think it is in his build thread. Get the felpro gasket, its worth the money. youll need the newer style black one.

[mjeff87]

97 was the chageover year for the cast aluminum to stamped steel cover....up to 96 takes the "older" style gasket, 97+ is the "new" style that uses grommets around the cover bolts. Either one works well, but I can say the only downfall of using the stamped steel cover is that it's thinner and you can hear more valvetrain noise than with the aluminum cover. Not a big deal to me, as just about everything on my MJ is noisy in one way or another....but if you're building/running something more streetable/daily driver, you may want to opt for the aluminum cover as it has more sound deadening capability.

 

Anywhoo.....with that said, here's my tech thread on swapping the cover, in case you need a hand :cheers:

 

(and yes, the cover bolts are 11mm as Tom mentioned...2.5/4.0 are the same as well)

 

viewtopic.php?f=2&t=12871&hilit=valve+cover

[KMAPRO]

Will the 96 cover fix my blow by problem? I am tired of putting 2 quarts of oil every other to three days...

 

I think the valve cover is leaking down the back side of the motor as well. I originally thought it was the rear main seal, but I now believe it just to be the valve cover. At least I hope so. I had every bolt out of the oil pan and beat on the oan for over 2 hours and still did not get it to bust loose.

[Randy in Maine]

If your blowby is from excessive wear in the piston rings, the best valve cover in the world won't help. Be sure to torque the valve cover bolts correctly.

 

I would do a correct compression test. Basically you run the engine until warm (about 5 minutes), remove the spark plugs, disable the fuel pump, open up the throttle, do 10 cycles of compression, write it down, do 10 more cycles, write it down, squirt a tablespoon of oil into the cylinder, do ten more cycles. Your compression would be the average of the the first 2 cycles. If squiting the oil in changes things by 10 psi, your rings may have a problem.

 

A leakdown test (properly done) will give you additional information as to just what is worn.

 

I also found that using Gum Out carb spray helped unseal the oil pan from the RTV sealant that some people use. Mine doesn't leak a drop.

[HellCreek]

If you are having a lot of blow-by around the valve cover gasket, you might want to check the crankcase vent tube at the rear of the valve cover. That would be the smaller plastic tube that goes where a PCV valve would normally be, which our engines do not have. I was getting a puddle of oil on the garage floor, so I checked mine, and the tube was completely stopped up from the previous owner not changing the oil at regular intervals. I cleaned the tube out and the blow-by stopped.

 

-Tom

[mjeff87]

agree with both posts above.....the only advantage of the later model cover is that they are redesigned to eliminate the "towers" inside the cover, replacing them with a baffle plate at the top. Some folks experience the oil-in-the-filter problem because the towers sit close to the top of the head inside the cover and thus closer to any pooled oil waiting to drain back into the engine. The baffle plate creates a distance between the head and the CCV lines, and oil isn't picked up so easily.

 

Jeff

[KMAPRO]

Well, I went ahead and picked up the valve cover from the 96 Cherokee at the local parts yard. I was able to get all the hoses and the fitting for the PCV hose that goes in the intake.

 

I only had one problem during the whole process. I made the mistake of only taking an 11mm socket, a screw driver and an adjustable wrench - no other sockets. As it turned out, at least on the one I was working on, the last bolt on the drivers side (closest to the firewall) was a 10mm.

 

Is this standard or was it just a fluke?

 

Anyway, one of the other guys on the lot was kind enough to lend me a 10mm to save me another trip out there.

 

I will also go ahead and check all of the other points mentioned in this thread.

 

Thanks for everyone's help.

[RLCollins]

I also have had trouble with the CCV line, which is the PVC Valve, it seem to be to small for real breathing. The oil it picks-up clogs the hard plastic pipe tubing. If it becomes totally blocked you end up with what appears to be oil leaks everywhere. along with the air cleaner being filled with oil. Remove this line and try to blow through it. You will probably find its totally blocked, If its as bad a you say that it is. I have been there and done that :chillin:

[KMAPRO]

Well I did get the valve cover changed out and the new Felpro gasket installed with minimal problems. I am a bit curious though, from everyone's postings, I should have had 11mm bolts. The only 11mm bolts I had were the ones where the wiring harness attached - the rest were all 10mm.

 

That rear bolt on the driver's side is a pain to get to.

 

OK, I did check all the tubing and they were all clear. I do still have a leak, but I feel pretty sure that it is a rear main seal. Now, I just need to find a way to get the oil pan to break loose and change out the rear seal. I will try the suggestion above to see if I can get that to work.

 

Thanks to all for their help and suggestions...