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?
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.
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.
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.
No, I don't even think I've heard of one cracking.So the two piece manifolds found on the 2000-2006 TJs aren't as prone to cracking?
No, I don't even think I've heard of one 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.