Has your exhaust manifold cracked yet? Here is a fix

HarleyMick

HarleyMick

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There is an undesirable side effect to all of that torque our favorite toy produces and that is a cracked exhaust manifold. In the 12 yrs I've had my 20 yr old Wrangler I have replaced one exhaust manifold and two headers. My exhaust man suggested the following fix which has worked out great:

Whether or not you have one of these:
Header new.jpg


You need one of these:
Flex joint new.jpg


When the engine twists it flexes just enough to take the stress off the exhaust manifold. Many newer vehicles come with one.
 
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Mine is cracked again. I think this is the 3rd one if had. I have seriously thought about doing this. Let us know how it works out. I really can't believe that they designed our exhaust to be as rigid as it is.
 
Brian83 said:
Mine is cracked again. I think this is the 3rd one if had. I have seriously thought about doing this. Let us know how it works out. I really can't believe that they designed our exhaust to be as rigid as it is.
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3rd one of what, exactly?
 
Brian83 said:
Mine is cracked again. I think this is the 3rd one if had. I have seriously thought about doing this. Let us know how it works out. I really can't believe that they designed our exhaust to be as rigid as it is.
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I also went through a replacement stock exhaust manifold after the original one cracked and I'm on my 2nd header. I added the flexible section when I put the Stroker engine in. So far so good and I have put it to the test. As FouledPlugs said, they put a flexible section on many new vehicles now. With a 20 yr old Wrangler I've had to do a few updates.
 
I must be lucky...my 2000 TJ bought new has never experienced a cracked manifold, now at 215,000 miles. Replaced the head gasket at around 190,000 so I had the manifold off and did a good inspection of it.
 
Thanks Mick. Makes a lot of sense. Wish I would’ve known it a month ago!
 
HarleyMick said:
Just curious, does your 2006 come with one? I was wondering what year they started it.
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Yes, the factory manifolds are susceptible to cracking. The fix that the some aftermarket companies devised was to include, “flex bellows” (their real name) in their revised/redesigned exhaust factory clone manifolds.


57C0E242-52DF-468D-838F-B8D6678BD040.jpeg


Edited: corrected misinformation.
 
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Fouledplugs said:
Yes, the factory manifolds were revised after reviewing service data and identifying manifolds as being susceptible to cracking. The fix that the engineers devised was to include, “flex bellows” (their real name) in their revised/redesigned exhaust manifolds.

I am not sure what year the Jeep engineers identified and remedied the problem.
View attachment 85461
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That is awesome! Every now and then design eventually follows function. Of course in any workplace policy and procedure rarely have anything to do with logic and reason. Good for them and good for you!
 
jjvw said:
The 4.0 never had flex bellows or couplings from the factory. What they did was change to a 2 piece manifold sometime around 2000.
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And - derail - if anyone has a super-clean set of those laying around, I'll be happy to take them off your hands for a reasonable price.
 
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