Putt-Putt...It sounds like a manifold leak?

[TJ Edge]

Ever since I body, motor, and suspension lifted my TJ, I have not been happy with the power, torque, or gas mileage.

Now, I fully expected to get lesser gas mileage with 33" MT/Rs; but I regeared with 4.10s so that the RPM's should be back to what they were when I had 3.73s and 30" tires. I figured that I should at least feel something *close* to the power and torque that I had before -- especially with the new Gibson exhaust I added with the lift.

So, now I'm getting like 12 mpg, I have much less power and torque, and I can hear a "putt-putt" sound coming from somewhere in front of the Cat. This sound only appears when I load the engine. If I rev it up without any load, the Gibson sounds like it should. If I'm accelerating into traffic or up a hill, the "putt-putt" kicks in and it takes me forever to get up to speed.

So, is it a cracked manifold? Or, could it be just an exhaust leak somewhere between the engine and the cat? Something else, perhaps?

TIA

[Steelheader]

TJ Edge, I have the exact symptoms you have, and I mean exact. I have looked over the collector where TJ typically crack and there's nothing. It is completely sealed. I have tightened all the manifold bolts as tight as I could turn the socket w/ a ratchet. I still have the exhaust leak sound. I did notice that tightening the bolts did affect the loudness of the leak, but didn't eliminate it. I bought a new exhaust manifold gasket today and will be installing it w/in the next week. It's driving me nuts trying to track it. :mad:

[Jerry Bransford]

Before my Jeep dealer installed the newer design exhaust manifold with steel bellows to eliminate the cracking, mine had been replaced twice only to have each replacement crack. If it's cracked, it's likely you can't see it. Even when the mechanic shined his flashlight right on the crack, I really couldn't tell it was cracked. It was only because he knew what to look for that he knew it was cracked. The newer design was first installed in new TJs in late 1999 so your '99 might have the old style that tends to crack.

I'm just saying that even if you can't see the crack, it doesn't mean it's not cracked.

[Steelheader]

Thanks Jerry. I think I will have my friend run a bead with his welder tomorrow between the 2 pipes where they come together. Maybe that will help. ;)

[Jerry Bransford]

You're welcome Steelheader but I hate to say that I don't think that welding the crack will last very long at all. The engine's torque flexes that joint pretty thoroughly and it will probably break again right next to the bead.

[projectYJ]

You're welcome Steelheader but I hate to say that I don't think that welding the crack will last very long at all. The engine's torque flexes that joint pretty thoroughly and it will probably break again right next to the bead.

He's right...mine's a 4.0YJ, but it had the same symptoms. I pulled mine off and welded it up myself in three different locations. It was nice and quiet for about a month. It looked as though the crack continued on underneath one of the welds. It ended up cracking about a 1/4" past the weld. The other two are still holding strong (knock on wood). Time for a Borla!

[Chris S]

Anybody recommend a good aftermarket header?

[Lauti]

I experienced some very nice backfiring when shifting down too early and the engines rpm came up to >3000!
The crack was clearly visible just above the collector ... I also got pretty bad gas mileage and there was zero acceleration. The exhaust manifold was replaced under warranty. No problems so far with the replacement - I would have to look up when and at what mileage it was replaced, if there's interest.

[JasonS]

Is there a mileage warrenty for the manifold?
I have what I think is the same problem as you guys.
I looked and couldn't fins a crack either, but now that Jerry says you may not even be able to see it unless you know what your looking for, I starting to wonder.
I've got 33,000, and I want to make sure.

[TJ Edge]

Before my Jeep dealer installed the newer design exhaust manifold with steel bellows to eliminate the cracking, mine had been replaced twice only to have each replacement crack. If it's cracked, it's likely you can't see it. Even when the mechanic shined his flashlight right on the crack, I really couldn't tell it was cracked. It was only because he knew what to look for that he knew it was cracked. The newer design was first installed in new TJs in late 1999 so your '99 might have the old style that tends to crack.

I'm just saying that even if you can't see the crack, it doesn't mean it's not cracked.


Jerry:

I do have a *very* early 1999 TJ. It was built in October of '98. So, I guess I've got the $hitty manifold.

Were you able to get the dealer to cover this under warranty? I see you are in Escondido. What dealer was this? North County Jeep? If they covered it, what mods did you have on the Jeep at the time?

I'm just worried that the dealer is going to say "Mods? No warranty, buddy."

Thanks a bunch...

[Jerry Bransford]

Yep, my servicing dealer is North County Jeep. My TJ had so many mods (lift, motor mount lift, tires etc.) on it by the time they finally put the final new-design exhaust manifold on it that I know they aren't (at least they weren't) fussy about mods. Too bad my old Service Advisor left, I could hook you up with him since he was great. Tom is the service dept. manager in case you get into a bind on this but you shouldn't have a problem. Get it taken care of before the 36K warranty runs out!

[Redeye]

I had the same problems on my 4cy. I had put a call into DC about this and they had told me that the exhaust manifild bolts are under warrenty along with the Cat. Conv. for 8yrs-80,000. The sooner you get it to the shop the better, also while they're in there they will check the manifold and replace at the same time.

If you think about hat crack is allowing it to suck in cold air and mix with hot air. It going to crack.

Your best bet is to have the dealer replace it b/c its free and then switch it over to an after market.

Good luck, to you all

[JasonS]

I just called my dealer to get my manifold checked out, and they said the TSB was only for the 2.5 l 4 cyl.

Not the 4.0 6cyl?

But they said they would check it out, and it would still be under my warrenty limit.

[TJ Edge]

I'm set with North County Jeep to get it fixed under warranty. 4.0 liter is covered, too. The Service Ripper said "TJ's are always cracking manifolds. We just replace them now. We used to weld them; but DC just said 'Don't waste your time.'"

He said it'l be done in less than one day. :D

Thanks, Jerry!

[JT's TJ]

My '99 was one of the very first off of the assembly line, so it would appear that I probably have the old manifold.

I have a couple questions:

* How many miles do you guys have on your vehicles when the manifold typically fails? I've only got about 13k (I travel a lot!).

* If the crack is small (microscopic!), can the symptoms be rather intermittent? I get a putt-putt sound occasionally, but I always thought maybe I was dieseling because I was in the wrong gear, or something.

* I gather there is a service alert for the manifold, but is this a recall item? Might I be able to get my manifold replaced preemptively, even if there is no sign of cracking?

[Jerry Bransford]

JT's TJ, there's no recall. Just pray it cracks before your warranty is up if you have the old-style header that doesn't have the big set of steel bellow that prevents the crack.

TJ Edge glad to see they're going to do right by you. Make sure you get the new style header, though I'm betting that's all they install now.

[Chris S]

[QUOTE]Originally posted by JT's TJ
[B]
* If the crack is small (microscopic!), can the symptoms be rather intermittent? I get a putt-putt sound occasionally, but I always thought maybe I was dieseling because I was in the wrong gear, or something.

The crack on my 91 XJ is big and obvious, but the symptoms are still intermittent. I usally get the "putt" noise when the engine is driven too soon after it is started (without a 30 second warm up), or after I rev it high. For me it usually goes away after 2 or 3 minutes.