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Discussion Starter · #1 ·
Alright, so I am a new member to the forum but I have searched this forum for a many things regarding my Jeep. I am new to all the rules so sorry if this answer exists out there, but I have not been able to find exactly what I am looking for.

I have a 99 TJ with the 4.0 L I6 and I have a tiny crack in my manifold which has come to cause power loss and lots of noise. I am short on money and time so at the moment I am looking just to temporarily fix the manifold and not replace it. For the longest time I simply had stainless steel foil wrapped around the whole and held in place with hose clamps but that has come undone. Does anyone have information on max temps put out by the manifold and if there is a kind of wrap that will withstand those temps? Also, could a ceramic high heat spray be used to seal the hole? Or is the ceramic coating strictly preventive.

Again, sorry if all this is already on the forum but I have had a hard time finding these specific answers. Thanks for any help
 

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I'm not an expert, but I did work in the engine testing field at one point. Temperatures just off the block can still be around that of inside the cylinder, and unless you removed most of your exhaust components, the pressures can still be pretty high.

I'm not sure wraps/sealants/etc will work for a long period of time. They will probably just be a bandaid fix. They might hold for a little while, but I'd probably try and find a solid manifold.
 

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The exhaust manifold is not difficult to remove, but there is a lot of stuff that has to be removed to remove it. Power steering pump and intake manifold to start with.

Once out it could possibly be repaired very inexpensively at a good muffler shop.

So if you have basic tools, and are good with your hands, you might be able to patch it up for about $10 or a cold six pack
 

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No patch will hold... if your stainless wrap worked "for the longest time" then you should probably just do that again....

Honestly tho, replacement is the only better solution.... even welding it will just have it cracking again right at the weld inbshort order
 

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Tend to agree with the above just replace it and be done with it. All that messing around with wraps, epoxy, welding isn't going to last long and could end up costing more than a manifold and gasket in the long run.

For around $100 you can fix it with basic tools and some common sense.

https://www.1aauto.com/search?q=exhaust+manifold&year=1999&model=454

A top tip for replacing the manifold....Remove the fender for easy access. Not hard to do adds about an hour to the job for removal and replacement. Label all the vacuum and electrical connectors so you know where they go when it comes time to put it back together. A to A, B to B, C to C that kind of thing.

Don't forget to spray all the bolts in penetrating oil the night before and use some high temp anti-seize on all the bolts when you put it back together.
 

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Discussion Starter · #6 ·
Thanks everyone for the advice. I'll probably just go ahead and look at a replacement. I've hesitated on doing that just because of the hassle of undoing everything to get to the manifold. As of right now this is my daily driver so time is of the essence. I've read many things on good manifolds and bad ones that will crack right away, any brands that seem to work for you guys?
 

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Discussion Starter · #7 ·
Tend to agree with the above just replace it and be done with it. All that messing around with wraps, epoxy, welding isn't going to last long and could end up costing more than a manifold and gasket in the long run.

For around $100 you can fix it with basic tools and some common sense.

https://www.1aauto.com/search?q=exhaust+manifold&year=1999&model=454

A top tip for replacing the manifold....Remove the fender for easy access. Not hard to do adds about an hour to the job for removal and replacement. Label all the vacuum and electrical connectors so you know where they go when it comes time to put it back together. A to A, B to B, C to C that kind of thing.

Don't forget to spray all the bolts in penetrating oil the night before and use some high temp anti-seize on all the bolts when you put it back together.
Thanks for the advice on removing the fender. Probably wouldn't have thought of that. :banghead:
 

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I've read many things on good manifolds and bad ones that will crack right away, any brands that seem to work for you guys?
I used the one that was in the link of my previous post although mine is a 4 banger. Haven't had it on long but great fit and comes with a Lifetime Warranty
 
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We have same issues, I attributed it to not disconnecting the exhaust the first time I pulled the transmission. The next time we disconnected the exhaust where the pipe connects to the manifold and supported the rear of the engine after removing the transmission mount.I was going to Tig weld it since that is how it was originally fabricated.
 

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I have to confess that I once tried using a "fireplace high temp caulk" as a temp solution...didn't work. I was hoping on I was on to something. lol
 

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Tend to agree with the above just replace it and be done with it. All that messing around with wraps, epoxy, welding isn't going to last long and could end up costing more than a manifold and gasket in the long run.

For around $100 you can fix it with basic tools and some common sense.

https://www.1aauto.com/search?q=exhaust+manifold&year=1999&model=454

A top tip for replacing the manifold....Remove the fender for easy access. Not hard to do adds about an hour to the job for removal and replacement. Label all the vacuum and electrical connectors so you know where they go when it comes time to put it back together. A to A, B to B, C to C that kind of thing.

Don't forget to spray all the bolts in penetrating oil the night before and use some high temp anti-seize on all the bolts when you put it back together.
I have changed 2 engines and an exhaust manifold, I removed manifolds on one of the engines first. I reviewed it carefully and found it unnecessary to remove/disassemble anything not required. If it were mine, removing the fender takes excess time, and the chance of additional issues is great. A good 3/8 socket set and a few combination wrenches you can change an exhaust manifold in a few hours.
While the manifold is off, inspect your freeze plugs, this is a perfect time to change them!!
 

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I have changed 2 engines and an exhaust manifold, I removed manifolds on one of the engines first. I reviewed it carefully and found it unnecessary to remove/disassemble anything not required. If it were mine, removing the fender takes excess time, and the chance of additional issues is great.
To each his own....Sure is a lot easier to get in there and work when you're not leaning over the fender with clear access to everything on that side of the motor. Something like 12 bolts 4 electrical connections and what 2 or 3 vacuum lines is really not a terrible task.
 

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Discussion Starter · #13 ·
Mission Accomplished

Well, I got her taken care of. Last night I spent about 7 hours changing out my exhaust manifold. A little long but all I had was a socket and a combo wrench, no power tools. Jeep really didn't think it through with the placement of the bottom bolts to the intake manifold. Extremely hard to reach, much less tighten correctly. At least with the basic tools. I probably could have invested in a couple things that helped. I did not end up removing the fender cause I was already pushed for time, BUT I can definitely see the benefit in doing so. All in all, it was an easy fix and just swapping things out, but also one of the biggest pain in the butts. No "easy" way of doing things on this one. Thanks for all the help!
 

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I put a Doug Thorley header on my 4.0 10+ years ago and it's never leaked it was fairly expensive though.
 

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Find a responsible guy in your area that does TIG welding and show him what you have, ask him for a price and if you remove the manifold, I bet it will be cheaper than any "quick fix". Miracles in a can are make believe.
 

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Thanks everyone for the advice. I'll probably just go ahead and look at a replacement. I've hesitated on doing that just because of the hassle of undoing everything to get to the manifold. As of right now this is my daily driver so time is of the essence. I've read many things on good manifolds and bad ones that will crack right away, any brands that seem to work for you guys?
I just bought a rear manifold for my 05 on eBay for 25 and they are over 200 new. I'm happy although I had to double check several sellers that they were not cracked before shipping as a couple found they were.
 

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Find a responsible guy in your area that does TIG welding and show him what you have, ask him for a price and if you remove the manifold, I bet it will be cheaper than any "quick fix".
Welding a crack in a TJ header normally results in another crack right next to the weld. The header design makes it vulnerable to the constant flexing caused by engine movement. Most good aftermarket replacement headers get around the issue by adding a pair of flex joints that look like compressed accordion bellows.

Like this...
 

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That is the type header we have but the crack is in 1 tube where it joins the other tubes at the flange. The factory welded those tubes using what was probably the tig process. The header on this jeep has the bellows but the crack is probably from someone not disconnecting the exhaust from the header before they removed the trans.

It doesn't make any sugnificant noise and was observed while laying under the jeep to install the transmission that was removed without disconnecting the exhaust.

The next two times we pulled the transmission we disconnected the exhaust and supported the back of the engine to keep it level.
 
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