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exhaust leak

S

sgtpepper

NAXJA Forum User
Location
RI
been a while, good to be back on the forum.

so my 98 with 220K miles failed inspection the other day on account of an exhaust manifold leak (and pads+rotors, but that's a no brainer)

I've wheeled and beaten it fairly well throughout the 220K lifetime. most recently on broken up and flooded roads following the Great Deluge of 2010.. so not surprising that something finally gave. in particular since i havnt put much love into the Jeep last few years.

following the failed attempt at getting inspected, i checked up on the exhaust and found no obvious leaks. but it was getting dark and I didnt have much under the hood time. i'll be back on it soon as it stops raining .. no garage :(

meanwhile, looking for any and all information on exhaust manifold leaks.
anyone with similar experience care to share?
any tricks on finding the leak? other than sticking a potato in the tailpipe hehe..

next step for me is to find the leak and see if I'm looking at just tightening some bolts or a cracked manifold.
limited information so far, i understand. will get back with some specifics, but figured i'd kick this off.

thanks-
 
check to see if the bolts on the manifolds are loose. on my 90 i could not see the cracks until i had it off. if you can see anything look for a little white by the welds.
 
In the winter this is easy... cold start it and see where the steam comes from. Right now, seafoam is probably a good bet. Another good way is to cold start it (so you won't burn yourself on the exhaust) and just run your hand along the pipes about 1/4" away till you feel gas escaping.
 
I suggest a search to find where people typically find breaks before looking. That will narrow down the area to inspect. You may need to be specific for leaks of 98's.
 
Cherokee 4.0L Exhaust Manifold cracks are very common and there are plenty of threads on the subject if you search the forum.

The simplest repair is to remove the crack prone stock manifold and to replace it with an APN manifold. - http://www.ineedparts.com/index.php?target=products&product_id=15343 - While you have the manifold out, replace the motor mounts. No manifold will last very long if your motor mounts aren't doing their job.

.
standard.jpg
 
Po' Man's stethoscope: 3' of vinyl tubing, one end stuck in your ear, move the other end around the exhaust manifold while the engine is running--you WILL know when the end is near a leak.
 
bingo .. Tim's got it. I have the classic manifold tube crack.

so does the spare manifold from the second 4.0 I keep for parts. :doh:

now the question is.. do i try to weld it (got mig)
.. or drop a few bux on the APN upgrade.


Tim_MN said:
Cherokee 4.0L Exhaust Manifold cracks are very common and there are plenty of threads on the subject if you search the forum.

The simplest repair is to remove the crack prone stock manifold and to replace it with an APN manifold. - http://www.ineedparts.com/index.php?target=products&product_id=15343 - While you have the manifold out, replace the motor mounts. No manifold will last very long if your motor mounts aren't doing their job.

.
standard.jpg
Click to expand...
 
joe_peters said:
Po' Man's stethoscope: 3' of vinyl tubing, one end stuck in your ear, move the other end around the exhaust manifold while the engine is running--you WILL know when the end is near a leak.
Click to expand...

Joe this tip is worth it's weight in gold. I nominate it "best tip ever". FWIW it also works great with 1/4" hose.
 
n1ywb said:
Joe this tip is worth it's weight in gold. I nominate it "best tip ever". FWIW it also works great with 1/4" hose.
Click to expand...

Hose doesn't work so good for us old farts with hearing loss. The vinyl tubing kind of accentuates the sounds for me.
 
that finger is pointing right at the spot where mine cracked, except I have about 1" of separation (no bumpstops allowed driveshaft yoke to meet downpipe). I was at the scrapyard to get a replacement, the first 2 XJs also had that crack. The third one looked good, til I got it off...I found a small crack where cylinder #4 tube joins the rear 'collector feed' tube.
I also have MIG, but am worried about introducing more weld stress. How about JBweld?
 
Be careful with a tube in your ear. If you find a significant leak, you can blow your eardrum out or cause some pretty significant pain if you have the tube too close or too well sealed to your ear.

RenegadeT, I would not use JBweld, it probably can't handle exhaust temps. Try one of those exhaust pipe fix-it kits that includes some heavy aluminum foil, hose clamps, and some sort of magic grey epoxy goop.

Other than that (and I haven't looked at a manifold carefully ever, and haven't looked at one at all in weeks, so I'm not sure this is even possible) maybe weld a flex joint into one of the two collector tubes? That way it will do the flexing instead of the spot where the two tubes combine.

EDIT: kinda like this, but right down at the Y-junction instead of on the #1 and #6 runners, looks like it would fit just fine, since you'd only need it on one tube. http://www.amazon.com/gp/product/images/B001OA2Z30/ref=dp_image_0?ie=UTF8&n=15684181&s=automotive
 
Don't waste your time trying to weld a crack. I have welded mine twice with no luck. It does not last long. It's the price you have to pay for owning an XJ. Buy yourself a new header and be done with it.

After all you can polish,polish,and polish a turd. And in the long run it's still a turd.
 
I've decided to upgrade the manifold and replace the motor mounts with Brown Dogs .. about $300 when all said and done.

not going to trust a reweld. maybe if i had the reweld done professionally. but even then, it's still going to be the weakest point.
 
Yikes, they sure are proud of that! I picked up the same thing for $19 or so at CAP a month ago.

It is exactly the part you want to use, though.
 
kastein said:
Yikes, they sure are proud of that! I picked up the same thing for $19 or so at CAP a month ago.

It is exactly the part you want to use, though.
Click to expand...

Yeah, that link is just a sample, you can find it cheaper even on amazon.com or eBay.

What is a CAP, other than something to cover your head--regional parts chain?
 
Yep. Consumer Auto Parts. Went there to pick up a flex joint to replace the blown-out one on my aunt's Rav4 on the 10th of May.
 
kastein said:
RenegadeT, I would not use JBweld, it probably can't handle exhaust temps. Try one of those exhaust pipe fix-it kits that includes some heavy aluminum foil, hose clamps, and some sort of magic grey epoxy goop.
Click to expand...

For some reason I thought JB was good for exhaust manifolds...I was wrong...http://jbweld.net/faq.php#faq002

I've tried about every exhaust goop/foil/clamp/wire at AutoZone...it doesnt hold up past the first warmup on an XJ header.
 
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