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Exhaust Manifold Swap, 4.0, TJ

8K views 16 replies 13 participants last post by  goinglong 
#1 ·
I need to change out my busted Exhaust Manifold on my 230,000 mile TJ. I think this will be about the max of my ability range. I am a patient man, however multiple trips to the parts store to complete one job really pisses me off. So, please help me figure out what I am going to need to start and finish this job in one shot. It looks like a fuel line disconnect tool is needed, and new injector connectors, etc.
Also, if there are any useful tips and tricks that would be appreciated as well. I am doing this job outdoors, in Maryland, in winter, on its tires.
So far I have the exhaust manifold, the gasket and a sort of collar that came in the box, I am guessing for connecting the downpipe.
Thanks!
 
#2 ·
Definitely will need some type of penetrant oil if you don't have any. Not wd-40. Kroil or pb blaster. I prefer kroil.

Haven't don't it on a jeep, but have other cars. Will need a good selection of wrenches, sockets, extensions, and swivels. Sometimes you need to build a transformer looking thing to get at some of the bolts.

Soak all the bolts for a while. I've had to soak for 24 hours before, squirting every once and a while with kroil. It's better to soak the crap out of them, then to bust out off in the head. (Been there, done that).


Kano Aerokroil Penetrating Oil, 10 oz. aerosol (AEROKROIL) https://www.amazon.com/dp/B000F09CEA/ref=cm_sw_r_awd_bsyNub0ANERAV
 
#3 ·
Well you're lucky it is in the 50's today and tomorrow. You should have everything you need but definitely listen to Link81. Spray the nuts on the the studs liberally with penetrating oil. Remove the ones you can but if some are very tight let them sit overnight with penetrant. If you break off a stud your patience will be sorely tested.
 
#4 ·
I second the kroil suggestion.

Not sure what year your jeep is but my 05 has 2 downpipe connections that can be undone from the top but i had to go underneath to reconnect them, and a second set of hands was necessary.

I will also suggest to have the correct size etorx but to remove/replace the manifold studs. Hopefully it isn't needed but better to have it than not.
 
#9 ·
I have a done a few of these on my 98 and one on my 97... The intake and exhaust share the same gasket. You will need to carefully disconnect all of the electrical connections on the intake. If you do this carefully then you should not need to replace any connectors at all including the injectors.

My fuel line to the intake is rubber so I do not even have to disconnect this but if yours is still metal then you will need to go to Autozone and get a fuel line removal tool. They are cheap and the ONLY way to remove the line without breaking it... Yes, this is why my line is now rubber... disconnect the throttle pedal cable and the shift down cable if its an auto.

If you have power steering, the pump and bracket and belt will need to be removed. You do not need to disconnect the power steering hoses, just move it out of the way. Next, disconnect the exhaust pipe from the exhaust manifold then reach up and remove the 4 bolts that hold the exhaust manifold and bottom of the intake to the engine. Lastly, remove all the bolts from the top. The furthest one back (towards the firewall) will be a pain.

There may be one of two small things I forgot to mention so look carefully to make sure nothing is still connected. Light shake the intake up and down and then remove it slowly as it is sitting on 2 dowel pins. If you lift up to hard you will break off the alignment tabs... Yes I have done this too....

Clean everything really good and then re install.

Good luck!
 
#7 ·
I changed the busted exhaust manifold on my 97 last fall. The intake and exhaust are separate but they share some bolts so they both come off when your changing the exhaust. Also when I changed my exhaust manifold the gasket I got was one gasket but for both the intake and exhaust I imagine yours is the same. When your putting it back together make sure everything lined up properly before you tighten everything up, there is a couple of pins sticking out of the head
 
#10 ·
One more thing... When reinstalling the intake manifold be sure it is seated correctly, there are dowl pins in the cylinder head used to align the intake to the head. If you don't have the intake seated correctly it will cause a large vacuum leak resulting in a VERY high idle.
 
#11 ·
If your changing the exhaust manifold, just cut the bolts between the manifold and down (front) pipe and replace with new, have patience, lots of Kroil, the injectors and rail do not need to be removed, but the release tool will be needed, if the bolts are very corroded, get new ones, there are special very thick washers that hold both manifolds, these will need to be reused, put it back together with anti sieze on all the bolts, and lots of patience, dont tighten any of the bolts until you get all of them started in a couple of threads
 
#13 ·
Looks like you've already got all the info you need. I x10 on the early and often spraying of penetrating oil, and try not to break a bolt. If you do, you can get a bolt extractor from any auto parts store for about 5 bucks, but it does take a lot of time and patience once they're broken.

My only suggestion is to sit back a bit, and you'll know what needs to come out just by looking at things. You'll know if a part needs to come out, because it will either be attached by bolts/nuts, or will be directly in the way.

Oh, and you'll more than likely end up with one of those double sided manifold gaskets. (One side perforated metal and the other side a paper-ish substance.) The metal side faces out away from the head. Make sure you have the correct torque and sequence when re-installing the manifolds.

You'll be fine!
 
#14 ·
Well things went as smooth as I could expect, A throttle body gasket would be one to add to the list. I did not get it finished today, there is one bolt on the bottom, over the motor mount that is impossible to to get back in. Another bonus to doing this job was the chance to clean out the buildup inside the head and intake manifold. It was pretty bad.
 
#17 ·
I tackled this one this morning and if you are worried about the cylinder head dowels, that should be enough to get you to remember to seat them properly. My buddy and I had the intake manifold seated but not properly but we knew to check to seating on the dowel and we were able to adjust it properly. before securing the bolts into place.

Overall, not a difficult job but you need to take your time. The link Sulkster posted is a real help.

Just a few hints (take them for what they are worth):
1. My 1999 TJ 4.0 Sport had a mix of American and metric bolts and nuts. I had both but I didn't have any deep ratchet attachments. If you can borrow some, you will be happy you did. My buddy also brought along his Snap-on swiveling extenders for his swiveling ratchet. They were a massive help to get into tight places.
2. Penetrating spray lube was awesome. Apply just a little while before you are going to take the bolts off.
3. After taking off the intake manifold and exhaust manifold my buddy need to have a little chat to convince me that the freeze plug nearest the firewall needed replacement. I just wanted to wipe it down and continue on until he tapped it with a screwdriver. That was enough to convince me. Just to be on the safe side, I would suggest that you grab a freeze plug at your parts store in the event you need to replace a freeze plug. There is no better time to do such a thing than when you have the manifolds off.
4. While removing all the header bolts, we were dreading putting them bock on. While we were checking for proper fit before securing the manifolds, we decided to try something just to see if it would work. We weren't going to spend too much time trying to make it work but we were hoping to save a little time putting it all back together.
We threaded the #1 and #2 bolts (according to Chrysler's manifold tightening sequence diagram) into the block before putting the intake manifold on the block. Then, we angled the bottom of the intake manifold so the bottom of it sat on the lower bolts while we tilted the top into a secure position. We were just a little high in seating on the cylinder head dowels but that was just a minor adjustment and the manifold sat right into place. If you will ever replace your exhaust manifold, you might give this technique a try. It will save you a some time and frustration in getting the center, lower bolts back into place.

All said and done, it took us 6 hours which included making a hot lunch, a trip to the parts store for a fuel line tool (planned at the start) and another trip to the parts store for the replacement freeze plug (unplanned).

Thank goodness for good friends to help when you ask them to help.

Now, time to get the JKUWW ready for the spring Moab trip!
 
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