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
07-01-2009 09:50 AM
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...
07-01-2009 10:45 AM
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.
07-01-2009 12:00 PM
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
07-01-2009 02:27 PM
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.
07-01-2009 02:59 PM
kik, where did you pick that up at? sorry for my ignorance, but where's the 'Quadratec'?
now the real question is: how bad would it be to just cap the hoses and let it ride?
07-01-2009 08:09 PM
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.