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How worried should I be about an exhaust manifold crack?

jeeperguy21

jeeperguy21

NAXJA Forum User
Location
Syracuse, UT
While I was trying to find the source of an oil leak yesterday morning, I discovered that my '99 XJ has a hairline crack about 1 inch in length at the very bottom near where it meets the down pipe. I don't visibly see or feel any exhaust coming out of the crack.

How serious is this? If it's not serious now, any estimates on how long it will last before it DOES become a problem? I'm in the middle of planning a wedding and it seems like ever since the day I proposed, I have found something almost daily that needs to be repaired/replaced on my heep. Let me hear what you think. Thanks.
 
I would say the biggest worry is it will be pumping hot gases into your engine compartment heating everything up. The longer you wait the bigger the crack , more heat, and annoying noise.

Maybe someone could chime in but I swear I remember Jeep doing a recall on the exhaust manifold on certain year 4.0 HO's as they were a defect and Jeep had to replace them?

My buddy had a 97' TJ and Jeep replaced his exhaust manifold on the recall and that was 5 years ago.
 
I've heard it can lead to burned valves. I got my XJ w/150K or so on it and the mani was cracked--it now has 189K and is still cracked--one of these days I'll get my new header installed. The cracks seem to more or less seal up when hot--I only notice any noise at all when the engine is still cold. I wouldn't ignore it forever, but I don't think it will cause any immediate damage.
 
I have had to replace or repair every freaking stock manifold I have ever had. It will progressively get worse, but chances are it has been cracked for a while and you just have not noticed it. The more flex and strain on the vehicle and motor will attribute to more rapid cracking and eventually failure. I can say that when it is close to that time, the noise alone will annoy you enough that you will already have it fixed. I am not promoting you to drive it for a long period of time, but it will get you by until you can get it fixed. As far as how long you an drive it, I drove a TJ with a small crack in the manifold for a year beofer I forked over the $ for a Banks header...that cracked also :D But it was covered under warranty!
 
mecompco said:
I've heard it can lead to burned valves. I got my XJ w/150K or so on it and the mani was cracked--it now has 189K and is still cracked--one of these days I'll get my new header installed. The cracks seem to more or less seal up when hot--I only notice any noise at all when the engine is still cold. I wouldn't ignore it forever, but I don't think it will cause any immediate damage.
Click to expand...

It does seem to be a lot louder when I first start it up after a cool night than after it has been running hot for a while. It makes sense that the metal would expand and sort of seal itself up while running. This is not on my high priority list of repairs at the moment, so I won't worry about this until I have the time to or I am forced to. Thanks for your input guys.
 
i drove my grand cherokee around for a while before i replaced the cracked headers. it didnt get much worse, just lost a lot of power and got bad gas mileage. you should be fine to drive it for a while.
 
I've driven a couple of XJ's with craked manifolds for months at a time and nothing bad ever seemed to happen. I only fixed them when the noise was bad enough for a tug by the law.
 
jeeperguy21 said:
..... I'm in the middle of planning a wedding and it seems like ever since the day I proposed, I have found something almost daily that needs to be repaired/replaced on my heep. Let me hear what you think. Thanks.
Click to expand...
THERE"S yer problem. Right There! Just dump the wife to be, and I'll bet that jeep runs like a top.:laugh2:
 
My header cracked a week after i bought the jeep, put 5-6k miles on it. Had a friend offer to fix it. It just doesn't sound like a jeep with out an exhaust leak..
 
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