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Cracked Manifold Problems

Fergie

Fergie

NAXJA Forum User
Location
Flagstaff, AZ
Well, not exactly the manifold, but the welds where all the pipes come together, before the down-pipe. Is this a common break? Recommended replacement options? What damage will it do?(gonna get it fixed in the next few days, but I need it between then.) Thanks all.

Fergie
 
My maifold had a crack in it and I took it to a muffler shop and it was 15 bucks to weld. The shop knew right away it was a jeep manifold so I think it is common.
 
yeah, i've seen the same thing happen on almost every 4.0 motor i've seen so far, regular 4.0's and HO's both do the same crack. every Xj i've had so far has had a cracked manifold at one point or another.

later

eric
 
What's the potential downside if Fergie delay's fixing the crack? I haven't seen any reply's addressing this issue.

Around 30K miles ago, the dealer told me twice I had a crack in my exhaust manifold.... I've done nothing because it hasen't done anything... I don't even hear an exhaust leak. Could I be breathing some exhaust fumes? Maybe that explains why I can't spell or remember my name.

My motor runs like a champ and I'm not dead so what's the downside hear.

Any Doctor's in the house?
 
Last edited:
You know, if it were me and I had a '91 or newer XJ, I would just have it welded along with a brace welded in to keep it from happening again. They are basically tube headers anyway unlike the pre-'91, non HO manifolds and are pretty efficient for a factory setup.
 
I just welded mine, I did not have the money for a header. But a real header would be ideal if you have the money 300.00 to 500.00 or 15.00 to have it welded.
 
I welded mine the first time, and of course it cracked again. If you can get to the crack, go on and get it welded and start saving your money money, cause it's gonna crack again.

Junkyard and factory replacements are short term fixes, 'cause it's the same design. The stealership price for a new manifold was more than a new Borla. (349.00 at truckperformance.com)

As stated, do a search for header. I chose a Borla and am very pleased with it.

HTH

John
 
89xj said:
for a replacement, do a search for "header".
Click to expand...

Sorry...should have clarified. If I had money for the header, then I would have gotten one. I meant "replacement options on the cheap" The local muffler shop wanted $189 to fix it, so I will be going to my mechanic tomorrow to get it fixed.

As to what damage it can do, my dad has said burnt valves and the sort.

Fergie
 
Hmmm, I'm confused about the post 91 tube manifold statement. Mine is a 88 and it's tube and yes it cracked too. I welded it about 3 yrs ago and it's doing fine. Make sure you clean it really good and make sure it's welded right. I wouldn't take it to your exhaust shop. Take it off yourself and then head down to your local welder since it sounds like you don't have the means yourself. I've found that most folks that call themselves welders at an exhaust shop only know how to weld up thin wall exhaust tubing and don't really know what penetration is about on something like this.

Sean
 
someone know what the difference is between a 91-92 Xj and 93-95? Borla lists 2 different models? I have a 92 and have been looking at a Borla but would like to be able to swap it to a newer XJ one day...... is it simply due to cat placement?


Chewy
 
ChEwBaCcA said:
someone know what the difference is between a 91-92 Xj and 93-95? Borla lists 2 different models? I have a 92 and have been looking at a Borla but would like to be able to swap it to a newer XJ one day...... is it simply due to cat placement?
Click to expand...

I'll take a couple of pics next week when I do the swap between a 94 and 92.

ChiXJeff
 
Hmmm, I'm confused about the post 91 tube manifold statement. Mine is a 88 and it's tube and yes it cracked too
Click to expand...

Here is a '91+ factory manifold:
dpstore_1738_66078712


Pre '91:
101111.jpg


Notice the longer runners on the 91+ and the 3 into 2 into 1 design rather than all six short tubes into one? Better scavenging and less turbulence with the latter design.
Hope this helped.
 
Mine is cracked on my 98 and i hear it is common. i dont know much about welding and was planning on fixing it myself. it is quite rusty and i was curious though as to what if the bolts break off?? i wasn't too worried about t but the more people i talk to the more this seems like a real concern. anyone know if i should be worried enough to be turned off of the job?
 
I've pulled two now and the bolts into the head gave me absolutely no trouble either time. I was more than a little surprised by that.

The bolts holding the downpipe flange on are another story, those were so rusted that I just cut through them between the flange and the clamp, popped out the stubs (they're splined press-fit, a little hammer work or a C clamp and socket will do just fine) then tack welded in some new bolts, forget if they were 1/4" or 3/8". Problem solved, for $1.50 in hardware and a dremel cutoff wheel.
 
Fergie said:
Well, not exactly the manifold, but the welds where all the pipes come together, before the down-pipe. Is this a common break? Recommended replacement options? What damage will it do?(gonna get it fixed in the next few days, but I need it between then.) Thanks all.

Fergie
Click to expand...

Common - and that area is called the "collector."

Primary cause is that the XJ exhaust system is quite rigid - reports from the field usually show that this sort of failure is accompanied (likely preceded) by failed/failing engine mounts. Check and replace PRN (don't repalce just one - if one is out, replace all three. Takes all of a couple hours anyhow.)

A more permanent fix would be to put a heavy-duty flex section (4-6") in the downpipe between the collector flange and the catalytic converter, to provide the necessary "give" in the system right where it would be most needed.
 
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