4.0 Exhaust Manifolds

Tech topics for the TJ and LJ (Unlimited) models manufactured from 1997 to 2006.
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Joined: Thu Oct 13, 2011 9:25 pm
First Name: Tim
Last Name: Jorgensen
Jeep Year: 2007
Jeep Model: JK (2007–2019 Wrangler)

4.0 Exhaust Manifolds

Postby Bugeater » Mon Aug 22, 2016 7:05 pm

What can you folks with later model 4.0 engines tell me about the factory exhaust manifolds? We have a 2004 LJ and the factory manifolds are two pieces, one for the front 3 cylinders and one for the back 3. I read on the net about how they are prone to cracking at the collector and that is what the guy we got the LJ from said happened to his. So he had replaced it with a header, but it has cracked also at the collector and needs replaced.

Wondering what kind of luck everyone has had with the factory manifolds and how long they last cause this header didn’t last all that long and they are pricey!

The factory manifolds are already obsolete and pricey as well if you can find them. So you are left with used or aftermarket knockoffs for OEM style cast iron manifolds.

Also wondering who has changed factory manifolds and how hard is it. I am not sure what brand this header is, but the design sucks! Took about an hour a piece to get two of the bolts out because of the routing of the tubes, couldn’t see bolts let alone get a wrench on them! It looks a lot like the Banks headers, at least by the pictures on their website. Sure wouldn’t buy one of those.

If anyone is running headers, what brand, how hard were they to install and how have they held up.

Let me know your opinions please! Thanks.

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