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post #1 of (permalink) Old 01-04-2005, 03:15 PM Thread Starter
 
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CJ7 Exhaust Manifold

Okay, so its an 85 CJ7 258 with a stock exhaust system, but the Mopar MPI. I think I may have a cracked exhuast manifold, but I'm not sure. It sounds like it and I can feel a leak underneath it, around where the manifold connects to the #4 or #5 cylider as you go towards the firewall. I'm assuming it is a crack as I've never had a problem with a manifold loosening up. So, is the OEM manifold prone to cracking? If it is a crack, do I need to get a new one or is it possible to fix the crack somehow? If I need to replace it, does it make sense to go with headers or not? Are they much of an improvement in mileage or horsepower? Anyone know of a good place to purchase a new manifold? I have found two places, 1A Auto on ebay has them for $90 or Best Automotive has them with free shipping and exhaust gasket kit for $130. Oh, this is my daily driver too. Thanks as always.

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post #2 of (permalink) Old 01-04-2005, 03:54 PM
 
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Re: CJ7 Exhaust Manifold

Depends on what you want to spend to repair, yes replacement is the best. I sold my spare manifold to one of the guys here on the board, I'm sure some one else out there may have a spare to sell if not look around the bone yards for a good replacement.
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post #3 of (permalink) Old 01-04-2005, 07:04 PM
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Re: CJ7 Exhaust Manifold

Most of the work of a repair is the removal and replacement. For a regular Bozo off the street I would repair a cracked one for $20 to $50, depending on the nature and location of the crack. That would be TIG welding with nickel rod, and should be a reliable repair, although some might not be feasible to repair.
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post #4 of (permalink) Old 01-05-2005, 11:12 AM
 
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Re: CJ7 Exhaust Manifold

You are going to wind up pulling it to be sure, unless you can see an obvious crack.
Maybe you will get lucky and it is just the gasket.

Even if it is not cracked, it might be warped.
If you find some mysteriously sheared bolts it may be warped. And it will do it again.

If warped or cracked, I would replace it.
They are not all that hard to come by and the cost to have a shop that can reliably weld cast is going to be close to or even higher than a used manifold.

Like Jim said, the right way is a TIG with nickle rod.
A stick with nickle or "super missle" rod is a close second.
But pre heating and post heating should be done. And not all welding shops either know enough or care enough to do it right. And few, if any will guarantee the repair.

Headers are not a bad option, but that gets into mod-ing the rest of the exhuast system and possibly some other mods to intake, fuel, etc, and may not be emissions legal where you are.
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post #5 of (permalink) Old 01-05-2005, 01:09 PM Thread Starter
 
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Re: CJ7 Exhaust Manifold

Thanks for the help guys. After reading your responses it makes more sense to replace it with a new one than to try and have it repaired or find a cheap used one. I don't want to have to pull it twice, not to mention removing the intake as well. I just don't want to have to pull everything and then realize it's just the gasket. Well, I'll let you know what it turns out to be.
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