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Intake manifold and exhaust manifold gasket replacement....

1990Pioneer

NAXJA Forum User
Location
Denver, Colorado
Hello group, I have to replace both of these gaskets. I haven't replaced these before but I can save a fortune by replacing them myself. I'm curious if there are any step by step instructions or videos out there?? Any pointers would be greatly appreciated! I have a 1990 Cherokee Pioneer 4.0L IL6 5 Spd. Thanks again!
 
make sure the manifolds dont get hung up on the alignment dowels in the block.... they have to sit on them, but not be hung up.... resulting in a leaking intake mani,

ive done it before, as have many others..... thats the only real 'duh' moment i can think of, everything else is similar to removing an intake and exhaust manifold on any other motor.... except it's 1 gasket for both.
 
The intake and exhaust gasket is a 1-piece gasket. I recommend using a Fel-Pro gasket and spray it with copper gasket spray. It is not hard to change, it is just a huge pain in the butt. The bolts are hard to get to - I highly recommend a 14mm ratcheting box-end wrench to help. I couldn't have completed the job without it.
 
Hello group, I have to replace both of these gaskets. I haven't replaced these before but I can save a fortune by replacing them myself. I'm curious if there are any step by step instructions or videos out there?? Any pointers would be greatly appreciated! I have a 1990 Cherokee Pioneer 4.0L IL6 5 Spd. Thanks again!

"These gaskets" are actually a combination gasket, which saves you some trouble.

Helpful hints I've found over the years...
- Replace the screws out of hand. Use SAE5 3/8"-16x1-1/4". (I prefer using brass or bronze, but they can be difficult to find. SAE5 will retain strength rather better than SAE8 will, with the "annealing cycles" of head-soaking & gradual cooling in service.)
- There is a LocTite that is formulated for exhaust use - I believe it's #271, #272, or @277. I'm not sure which offhand, but it's easy enough to find out. If you can't find it at your parts house, you can probably find it at an MRO house (that's where I got my bottle.) Don't bother with anything else - the head will break it down.
- It's not necessary, and people have argued with me over it, but I give the gasket a light coat of RTV Copper on both sides before I put it in. Differential thermal expansion is an issue on the long inline six engine; with the iron exhaust, aluminum intake, and common gasket. This is also why I check torque on the screws annually - I usually find a couple loose, particularly bottom back. The annual check is a good idea.
- DO NOT LOSE THOSE LITTLE BOWL-SHAPED WASHERS! They're there for a reason (differential expansion, again.) Reuse them. Don't replace them with flat washers - they don't work the same way (if you have to replace them, source Belleville spring washers. I'm working on kits.)
- Studs - they're there for a reason. Having two (one at each end) or three (each end and top centre) will give you something to hang the exhaust on while you're getting the intake in place. They may be replaced with studs cut from 3/8"-16 threaded rod (cut them about 2-2.25" long, and dress the cut ends with a file or grinder,) and install. Again, you can use brass or bronze (I usually use brass threaded rod - it's readily available,) and standard carbon steel threaded rod is typically H&T to SAE5 specs.
- Torque spec is 19-21 pound-feet. Remove the screws in an anti-clockwise spiral from the front end, install in a clockwise spiral from the top centre.
- Removing your EGR tube before you untorque the manifolds will make it easier to manipulate your manifolds, torquing it up last is best & easiest. You may use never-seez on the flare nuts, but torque to 2-3 flats past finger tight (with or without never-seez. "Torque angle" is not affected by the presence or absence of any particular lubricant, unlike the "applied torque" method. Ninety degrees, after all, remains ninety degrees no matter what.) The EGR valve proper may be left in place, just be careful to not whack it on anything. A new EGR gasket can be cut from high-temperature gasket material, and a thin coat of RTV copper may be used there as well if you like (yes, it will hold up to the heat - I use it on all of my exhaust gaskets. Don't get silly with the stuff, just use a thin, even layer.)
- Go to Sears and get a 9/16" "flex" socket (short socket with inbuilt universal joint.) This makes the assembly at least an inch shorter at the socket end, and makes it easier for you to get your socket on the rear lower screws. No adjustment to "book value" torque is necessary with a universal joint - it's a low applied torque, and the universal joint is theoretically a straight coupling (just like an extension rod.)
- Replacing the collector stud nuts with brass won't go amiss - 3/8"-16 for those as well.

That's what I can come up with offhand - I'm not exactly in "working mode" right now. But, that should help you.
 
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