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Discussion Starter #1
My 89 4.2L YJ has a broken exhaust. It rusted through right after (engine side) the cat. The pain is that the exhaust is all welded together. So I went and bought a new exhaust system and am getting ready to put it in, until i look and see two other pipes that are welded into the pipe that runs from my cat to my exhaust manifold. they are welded in and run up towards my air cleaner. not being a welder, my question is: is there any way i can put a new exhaust system in and not weld those two lines into the new system? And what do those two lines actually do? Thanks in advance
 

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Sounds like its the 3/4in bypass from the cat to the exhaust manifold. Im in Texas and mine is a deer lease jeep, so I just welded them closed. Your emmision in MA. may not allow you to do that, but if its a crawler you shouldnt need it..you do have to cap it or bend it over maybe weld it, cause if you dont it will sound like the biggest exhaust leak ever...
 

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i had mine(89 and90 yjs) welded. no difference in performance. got rid of the constant ticking. there are valve thae go on the large pipes. very expensive. if you can do away with them i would.
 

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Discussion Starter #4
since it's an 89 i won't have to pass emissions which is good, but i just want it to be quiet enough not to get pulled over (which by installing a new system, it will). i am just worried about screwing up something by capping them since it's my DD.

thanks for the imput
 

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I have an 89 4.2, 5spd. When I replaced the exhaust system and Cat I got the Air Assembly Kit that attaches to the Cat from Quadratec.
 

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Discussion Starter #6
kik, where did you pick that up at? sorry for my ignorance, but where's the 'Quadratec'?
 

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Discussion Starter #8
now the real question is: how bad would it be to just cap the hoses and let it ride?
 

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Running an invisible cat, I cut the small tube just below the exhaust manifold connection. Leaving about 4" of the 3/4" tube, I used the 3/4" U-bolt clamp from the cat end & a copper sweat cap from the plumbing aisle.

Can't remember what size it was, but I bought a few sizes near what I thought & returned the unused ones. The copper cap fit inside the exhaust tube.

The other line coming from the air cleaner to the cat was omitted.

The other U-bolt from the cat needs to be saved, since you won't find one anywhere. PB blaster did the trick.
 

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Discussion Starter #10
thanks buck. much appreciated
 

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thanks buck. much appreciated
Your welcome, Just be sure about the inspection waiver before cutting anything. Even then, federally speaking it's not exactly leeegull.:banghead:


Basically you bypassed the cat is what you are saying?
Did I say that?:confused::D:rolleyes:;)

That kitty puked it's guts out anyway, so I put it out of it's misery.:wavey::punk:

Meantime I used a test pipe. When I'm all done testing, I'll post the results here in this thread.
 
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