Did your cracked exhaust manifold look like this? - JeepForum.com
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Unread 03-30-2010, 06:36 AM   #1
EABiker
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Did your cracked exhaust manifold look like this?



My 4 banger was sounding a bit rough, but running fine. I figured the manifold gasket was blown; it was, but so was the manifold!. I've read that Jeep mamnifolds would crack from trail damage issues, but this is clearly not the case here. It looks to me that this thing has been hot, very hot, and has actually began to melt! It could also have been splashed with water when it was hot; that could explain the odd cracking in the center, Or, perhaps that country of origin stamped into it had something to do with it.......
Anyway, I have been wrenching on vehicles for nearly 30 years, and never saw a manifold like this!

NAPA did have one in stock, so the story did have a happy ending!

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Unread 03-30-2010, 06:41 AM   #2
Louie4
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Never seen one like that. The crack on mine is where the pipes meet above the flange, as most 4.0's are. I've even replaced mine once. That looks nasty, hope the new one is a bit more durable.
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Unread 03-30-2010, 07:15 AM   #3
Que89YJ
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You were running hot to cause the heat generated to do that kind of damage!
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Unread 03-30-2010, 08:06 AM   #4
Burnerman
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Was/is the EGR hooked up on that engine? It's weird that it heated so bad in just that area yet the front and rear runners don't look that bad. It is probably a thin cheap cast in the center chamber that overheated. If the EGR is diconnected it will cause hotter EGT's.
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Unread 03-30-2010, 08:36 AM   #5
EABiker
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Everything is hooked up, and I actually just passed emissions testing! Unfortunately, the new one I got came out of the same casting mold as that one did. I was wondering of the "factory" manifolds were also made in China! It would be hard to tell though with the heat shield in place.
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Unread 03-30-2010, 09:10 AM   #6
Burnerman
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No factory Chinese manifolds. All made in USA.
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Unread 03-30-2010, 10:35 AM   #7
YJdad
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Actually - it looks like the heat shield has been removed? or that it never had one. Those cracks would be right under it.
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Unread 03-30-2010, 10:52 AM   #8
EABiker
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The heat shield was in place on the engine; It fell apart on the way off of the Jeep.
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Unread 03-30-2010, 11:13 AM   #9
leadsled01
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I think that cracking was caused by cold water splashing onto the hot manifold.
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Unread 03-30-2010, 12:40 PM   #10
sebastian22
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just curious, how are your motor mounts? there may have been too much vibration in there due to bad mounts that caused the cracks.
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Unread 03-30-2010, 03:00 PM   #11
EABiker
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Actually, I did replace the mount, which was bad, while doing the manifold job!
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Unread 03-30-2010, 03:05 PM   #12
sebastian22
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my manifold had 2 cracks in the same spots as yours, although not as bad, they were more hairline, those look much deeper.

anyway, i always suspected that it was because of extra vibes caused by disintegrated motor mounts.
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Unread 03-30-2010, 05:36 PM   #13
Billyjoebob007
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Replace it with this :

Jeep Exhaust Manifold - iNeedParts.com

Whoops, my bad, yers is a 2.5.
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Unread 06-04-2010, 05:07 PM   #14
ditchdog
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My buddy just showed me his manifold off a 1.5L Iron Duke... looks almost the same plus stress cracks all over. Must be from heat, but his just passed CA smog??? Anyone know of a place to find a new/used exhaust manifold for an '80 1.5L Pontiac Iron Duke?
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Unread 06-04-2010, 06:51 PM   #15
clush
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That is CRAZY. I think the cause is just cheap metal from China, maybe with some help from a hot engine and water splashing on it over multiple offroading trips. I used to mess around with drag cars before I started playin with jeeps and those cars mostly had headers - but they get hot as heck and I have seen some manifolds on those cars too. but never saw anything like that. I can't help but thing something was wrong with the metal or how they casted it.
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