Front-to-back exhaust question

Joe907

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Hello all! I love that I can often find answers to questions I have right here! My question is however surprisingly nowhere to be found. I just turned over 137K on my 4.0. The cat is toast and I have a leak at the manifold so I want to replace the entire Exhaust system. I've read that the manifold isn't a manifold, but is a header, then its "kinda a header" O.K.!?!?. Anyway, should I just stay with a stock system all the way around or do you have a preferred combination? it seems I don't gain much with any "upgrades" so what are you running and what is your opinion based on your experiences?

Thanks!
Joe
 
What year is your Jeep?

First and foremost, you'll want to see if that leak at the manifold is a crack in the manifold itself, or just a old / leaking exhaust gasket.

If it is the manifold itself, don't waste your money on a new one. Simply take it to any competent welder and have them weld the crack. DO NOT under any circumstance be led to believe that 'headers' make a difference on these engines. The headers they sell for the 4.0 found in the TJ, are not even full headers, and therefore you won't gain any real power.

Next up after the exhaust manifold you'll want to replace your stock mid-pipe (the pipe that has the pre-cats in it) with a new one.

Bosal makes a good replacement mid-pipe, with both the cats already in it:
https://www.amazon.com/dp/B0049AYRFQ/?tag=wranglerorg-20

After the mid-pipe is replaced, your best bet is to go to a competent exhaust shop and have them build you a cat-back exhaust. I had this done for around $250, which included a nice Magnaflow muffler.

You'll also need a catalytic converter (https://www.amazon.com/dp/B000C946KE/?tag=wranglerorg-20) to replace the one that is under the vehicle.

Do not be tricked or fooled into paying $500+ for one of those Borla (or similar) bolt-on catback exhausts. They're wayyyyyy overcharging you for those things, because an exhaust shop will build you one for around $250 like I said.

Unfortunately there is no all-in-one solution for the TJ (like there would be for some performance vehicles). You have to piece it all together using the pieces I mentioned above (or similar).

That isn't that big of a deal, you just have to be prepared to spend a little, because catalytic convertors are never cheap (and if you buy some cheap Chinese one, it make create running issues or check engine lights with your vehicle).
 
I agreed with most of what Chris said above with a few comments. I like to weld but welding a cracked TJ exhaust header is not a permanent fix, at least not in the TJ header's case. The TJ's header cracks where it likes to flex and if one crack is welded, another crack will form right next to the weld.

Definitely true that you're not going to see a performance boost by going to an aftermarket header without doing other work on the engine too.

Since the main point of your post Joe was your cracked header, I will guess you have a 97-99 TJ. Those model years were infamous for cracking their factory header, mine cracked three times before the dealer installed the upgraded/more flexible factory replacement header that came out mid-1999 model year.

If that's what you have, its problem is that it doesn't have any way to flex at the two points it commonly cracks at. The engine rocking back & forth due to torque is what flexes then cracks them.

I would not install one of those expensive Borla headers or the standard Banks headers either. They'll crack just as fast and 3X the cost. The Banks Revolver header is worthy and won't crack but it's also 3-4X as much to buy as non-name brand headers like are sold on eBay.

The factory came out with a more flexible design that incorporated two flexible steel bellows at the two points it normally cracks at. Like the below header, you can see its steel flex joints inside the red outlines. Such headers are not expensive and are available in the aftermarket on places like eBay and Amazon.com. Most people report good luck with them. That's the way I'd go if your TJ is a '97-99 like my guess is.

HeadersWithJointsCircled.JPG
 
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To elaborate on what Jerry said, I was assuming you had 2000-2006 TJ, in which case the exhaust manifold is much different than the one Jerry posted. I've never really heard of the later manifolds cracking.

However, if you have the earlier exhaust manifold like Jerry posted, I would not weld that one either. That one will just crack again if it is welded.
 
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i know that this thread is a bit old, but does anybody have any experience with Pacesetter Catalytic Converters?

Never heard of them. But a cat is a cat... Just throw one on and be done with it. The "high flow cat" thing (assuming that's what this is) is just snake oil.
 
Here's some common symptoms of bad cats:

Sulfur smell
Large fuel economy decrease
Failed emissions test
Check engine light
Discolored or warped outer housing
Noticeable lack of acceleration
Hard starting or no-start condition
Noise coming from cats (mine did this since the insides were falling apart)
Glowing red cats
 
I know it’s an old three but just curious if you have an update on the pacesetter cats... aligning up correctly, no leaks? Etc...
thanks

It aligned perfectly for me, no leaks. O2 sensors went in and those aligned just like the OEM cats. out of all the replacement cats that i searched for these were the best. Mandrill bends and stainless steal, really decent quality. if i had to do it again, i would buy it again.
 
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