Locating Potential Exhaust Leak

Schyler

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Mar 29, 2025
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Pensacola, FL
This is my first post, so sorry if what I am about to talk about is already being discussed or if I'm breaking any rules or whatever.

I've got a 2005 Wrangler Unlimited with 132,000 miles. I've had a number of symptoms that lead me to believe that I may have an exhaust leak.

Firstly, the floor boards get really hot when driving for an extended period. I think the inner boot for the shifter needs to be replaced which may help with that issue, but I also think that the heat is in too great of an area to just be a result of a torn inner boot. I can feel it through the rubber mats, the bedrug, and even the insulation the previous owner put down because she had the same issue, so supposedly it used to be even worse.

Secondly, my gas mileage is absolutely abysmal. It's on 33s with I believe a 5.5 inch RC lift (which I will be reducing to 4.5 inch metal cloak lift) with stock 3.73 gears, but I still think the gas mileage is worse than it should be. I drive an average of about 50-100 miles a week and I have to refuel every week to week and a half. Both this and the hot floorboards lead me to think that the system is running rich due to o2 sensors detecting lean because of a leak.

Thirdly, there is a tick. While I was looking at the exhaust manifold and pre-cat area from under the jeep, I probed the bolts that connect the pre-cats to the rest of the manifold, and discovered that one of the bolts on the rear cat was loose. I obviously tightened it, then tested the other bolts and snugged them a bit. The tick is still present, but I do not remember if tightening up those bolts changed the noise in any way (like the ticking having a different pattern of being quieter or something). I like to think that it might be quieter. I have also not done a long enough trip yet to see if the floorboards will get hot again or to see of mileage is improved since I tightened the bolts only a couple days ago.

I did just try the soapy water and leaf blower-up-the-tailpipe trick and could not see any bubbling in the areas accessible for me to spray. But I don't think I can make any real conclusions since I could not spray or see the part of the manifold directly underneath the intake. My muffler is kind of shot though and has a ton of small holes (which I will eventually replace with probably a flowmaster or banks monster), so I also wonder of the air from the leaf blower was even making it to the manifold. I think it must have, since air was coming back out of the tailpipe which would indicated that the entire exhaust system was filled.

So what would the more experienced members' suggestions be with proceeding? Should I remove the intake manifold and take a better look at the exhaust manifold? I am just hesitant to remove parts with gaskets since I've had bad luck with proper sealing, but that's probably because I'm a noob. I am also aware that the ticking could be the lifters. The fan is too loud for me to be able to hear if the ticking is still present or changes with increased rpm which would help indicate lifter tick vs exhaust leak.
 
Floorboards get hot. It's a TJ. Back in the day you could buy racing socks made of asbestos but they're hard to find now. Exhaust manifolds like to crack on the 4.0 and make tick noise. Lots of other things make tick noise. Try a mechanics stethoscope to pinpoint the origin.

Personally I wouldn't remove the manifolds unless dire necessity. Dire. They can be a bear to remove, and reinstall, especially when the studs snap off.
 
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Seafoam the engine.

Start it up, pop the hood, crack open a can...pull the tube off the brake booster...hand on the throttle body linkage...dip it in the can and keep it running.

Use a GoPro or friends to watch and see where the smoke comes out.

-Mac
 
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Seafoam the engine.

Start it up, pop the hood, crack open a can...pull the tube off the brake booster...hand on the throttle body linkage...dip it in the can and keep it running.

Use a GoPro or friends to watch and see where the smoke comes out.

-Mac

Don’t do this in your garage, driveway, or neighborhood. It makes an abominable amount of smoke. I was fore warned and did it at the edge of town on a farm road, and I was surprised no one called the fire department.
 
Seafoam is great advice. Applying it somewhere that doesn't fill the house with the fumes and the significant other with rage is probably even better advice! We found an exhaust leak at a coupler on my son's 2000 that we had never noticed, simply because we were running some top end cleaner through his throttle body. That extra smoke makes any leaks easy to see. Just make sure everything is cold to give you the best chance of finding those leaks.

Soapy water usually works well, as does a smoke machine. I picked up a very reasonably priced smoke machine off the internet auction site, and have used it quite a bit. The smoke machine was the only thing that helped me spot a pinhole leak up under a heat shield by the pre-cats on my other son's 2006 that had been making the tell-tale click and giving his 02 sensors fits. That one was entirely concealed from view, until we saw the smoke wafting out from under the heat shield. You can inject the smoke (engine off and cold) through an 02 sensor hole or through the tailpipe itself so long as your cat is stone cold.

I'd also second the recommendation to check thoroughly for leaks, especially under the hood, before you pull anything apart at this stage. Good luck!
 
I just finished loosening then re-tightening the flanges by the precats. Upon startup, it sounded like the tick was gone, but then it slowly presented itself back to how it was. This may just have been me not able to hear it during the higher-rpm startup until it dropped to idle rpm range. When revving the engine, the tick frequency increases with engine rpm, but does not get louder.

I will try the seafoam trick sometime this week and get a mechanic's stethoscope for further diagnosis.

As far as warm floorboards, I replaced the inner shifter boot (which was ripped), and that seems to have helped a little with floorboard heat, but has helped majorly with cabin heat, because it seemed like the AC couldn't keep up until now, so that is a positive. I have seen lots of threads where members lessened the floorboard heat by changing the inner shifter boot, but I'm still confused as to how that would affect floorboards since the inner shifter boot is above them.

Another problem that I think may be linked to either an exhaust leak or failing o2 sensors is that, after a recent trip I had (about 40 minutes), I experienced some rough idling where the jeep would basically go down until it sounded like it was about to die, then revive itself with a big rev and repeat. This was with the AC off because I had the top off, so idling was lower rpm, and I don't think this would happen with AC on. Based on my research, rough idling when the engine is at temp is probably some kind of exhaust problem, be it a leak or o2 sensors going bad.

I appreciate the responses though. Obviously an exhaust leak should be easier to identify given the above methods than it feels.
 
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Blow some smoke up its @$$. You'll see where it's leaking out. :cool:
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