How can I tell if I have a cracked exhaust manifold?

Rook

TJ Enthusiast
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Aside from visually inspecting it, are there any other symptoms of a cracked exhaust manifold on a Wrangler TJ?
 
Well, first off if you have a crack it should be noticeably louder (which should be obvious if you have a stock exhaust). Also, often times you're able to hear the valves ticking more (particularly on start-up) from what I've read.
 
Just had mine replaced when I put in new engine as was cracked on bottom and top. My mechanic said wasn't unexpected cause if you have a TJ model and you haven't replaced it by now, trust me it's cracked.
 
Just had mine replaced when I put in new engine as was cracked on bottom and top. My mechanic said wasn't unexpected cause if you have a TJ model and you haven't replaced it by now, trust me it's cracked.

Could you visibly see the cracks on yours, or were they too small to see?
 
I'm in the tax and investment field and not at all mechanically inclined so I have a mechanic. I would initially say no because I took the jeep to him when I bought it and asked him to give it a once over and did about $2200 worth of work and he didn't see the cracks. The differential and steering module went out a few weeks later so back to the shop and didn't notice the cracks but to his benefit wasn't looking for them. Next time I drove it the engine lost pressure in one cylinder. After some tests and 3 mechanics looking at it we decided best plan was order a new jasper engine for it. When he pulled off all my new parts to pull the old motor he found the exhaust manifold cracked on top and bottom and the coil cracked. Needless to say I've pretty much replaced most of the jeep at this point and I officially own the most expensive 1997 TJ.

Could you visibly see the cracks on yours, or were they too small to see?
 
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Good lord man... Sounds like you ended up with a lemon! I guess it's a good thing you're brining it back to life though.
 
Yeah I almost burned it to the ground or left it in the yard but figured I'd just have a $7000 paperweight if I didn't fix it. So luckily I have a mechanic I've trusted for years. You know it's bad when your mechanic almost cries that he has to call you again.

I bought from a friend of brothers so stupidly believed his speel about just spent $1200 fixing her up. He spent a lot of time hiding things for sure. Mechanic started digging deeper after 2nd repair visit and looking at fluids and condition of parts coming off it's doubtful he did any maintenance. Their opinion was it had "set up" not running for a long time. Once they pulled the engine they found a lot of damage to front drive shaft so the 4 wheel drive will need to be repaired but I've out that off this after the holiday. After they repair the 4 wheel drive I will have pretty much replaced everything but the transmission, transfer case and body.

She's costs me about $8k in repairs cause I have to pay shop rates rather than do them myself but she purrs like a kitten and she didn't end up in the junkyard. I wasn't looking to sell her so doesn't matter if she's not worth what I paid.

Good lord man... Sounds like you ended up with a lemon! I guess it's a good thing you're brining it back to life though.
 
Yeah I almost burned it to the ground or left it in the yard but figured I'd just have a $7000 paperweight if I didn't fix it. So luckily I have a mechanic I've trusted for years. You know it's bad when your mechanic almost cries that he has to call you again.

I bought from a friend of brothers so stupidly believed his speel about just spent $1200 fixing her up. He spent a lot of time hiding things for sure. Mechanic started digging deeper after 2nd repair visit and looking at fluids and condition of parts coming off it's doubtful he did any maintenance. Their opinion was it had "set up" not running for a long time. Once they pulled the engine they found a lot of damage to front drive shaft so the 4 wheel drive will need to be repaired but I've out that off this after the holiday. After they repair the 4 wheel drive I will have pretty much replaced everything but the transmission, transfer case and body.

She's costs me about $8k in repairs cause I have to pay shop rates rather than do them myself but she purrs like a kitten and she didn't end up in the junkyard. I wasn't looking to sell her so doesn't matter if she's not worth what I paid.

I've been in that situation before where I bought a car from the previous owner, taking their word for it that they recently performed a ton of maintenance on it. I learned my lesson and never believe that anymore unless someone either has the receipts to prove it, or I can simply tel by inspecting everything that it was owned by someone as anal and OCD as myself.

The good thing is that now since you've done all this maintenance it should last you for quite a while!
 
Back to the question of how to find a cracked manifold. If you slowly drip ATF into the throttle body as it is idling it will produce a large amount of smoke and will show up at every leak.

Really? And that has no ill side effect on the engine other than smoke?

If so... Very useful tip. Does it have to be ATF?
 
My previous TJ had several cracked exhaust headers (manifolds) and I could never see any of the cracks while they were still mounted. The dealer mechanic spotted my TJ's first crack but even when I looked with a flashlight, I couldn't find the crack. It did however make an odd little raspy/chuffing/shuffling sound while idling which is about the best way to know it's cracked. Early TJs up through about mid-99 had a problem with cracking headers.
 
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My previous TJ had several cracked exhaust headers (manifolds) and I could never see any of the cracks while they were still mounted. The dealer mechanic spotted my TJ's first crack but even when I looked with a flashlight, I couldn't find the crack. It did however make an odd little raspy/chuffing/shuffling sound while idling which is about the best way to know it's cracked. Early TJs up through about mid-99 had a problem with cracking headers.

So the two piece manifolds found on the 2000-2006 TJs aren't as prone to cracking?
 
Reviving this old thread to ask: other than the sound described by @Jerry Bransford in post #13, and other than seeing the crack, what are some other signs or symptoms of a crack?

I recently noticed a sound that I would describe as being a bit like a soggy playing card fluttering in a bicycle spoke. (Did anyone else do that as a kid?) That sound sent me searching for this thread, and I'm wondering what else I can check or look for as a sign of a crack. For instance, I also noticed recently that I'm getting very low MPG, and am wondering if that could also be a sign. (By "very low", I mean about 14 MPG, whereas I remember when the TJ used to get the advertised 18–21 MPG.)

I know the TJ did have a cracked manifold back in 2001. It was repaired by a dealer at the time. Mine is a 97 2.5L.

Edit: @TJ4Jim, this thread suggests that you might have some insight.
 
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Reviving this old thread to ask: other than the sound described by @Jerry Bransford in post #13, and other than seeing the crack, what are some other signs or symptoms of a crack?

I recently noticed a sound that I would describe as being a bit like a soggy playing card fluttering in a bicycle spoke. (Did anyone else do that as a kid?) That sound sent me searching for this thread, and I'm wondering what else I can check or look for as a sign of a crack. For instance, I also noticed recently that I'm getting very low MPG, and am wondering if that could also be a sign. (By "very low", I mean about 14 MPG, whereas I remember when the TJ used to get the advertised 18–21 MPG.)

I know the TJ did have a cracked manifold back in 2001. It was repaired by a dealer at the time. Mine is a 97 2.5L.

Edit: @TJ4Jim, this thread suggests that you might have some insight.

Bump!
 
our TJs have two types of exhaust manifold: those that have cracked, and; those that have yet to crack.

I use an old doctor's stethoscope with the end snipped off so it is just an open rubber hose connected to the ear pieces. You will be able to identify if there's a crack or a leaking gasket very easily-engine running, of course.
 
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I check for leaks by having somebody hold a balled up towel inside the exhaust pipe and place my hand near potential leak spots right after it's first started up. You have a good 30-60 seconds before it gets too hot to hold your hand in the general area of the exhaust manifold. You'll feel the leak.
 
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