Any tips on catalytic converter replacement?

Steve3740

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Apr 8, 2018
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Location
New York, USA
so I just finished my winter project of replacing the tub on my 03 Rubicon. I took it out on the trail for a test run and it seams like my rear main seal is leaking. I cant seam to get a good angle on the bolts that clamp the catalytic converters to the exhaust manifolds. was not hard to do when the tub and fenders were off. any one have any tricks to getting these out? also what size bolt are those. I can get either a 14 mil or 9/16 on some of them but then does not seam to go on to the other ones. any help is greatly appreciated.

thanks.
 
It's a goddamned nightmare.

I just did mine back in February.

It took nearly as long to get the old ones off as it did to put the new ones on. There's just no good way to get on the bolts that I could find. It's made worse by the fact that the flanges sort of mushroom down preventing you from using a box end wrench, and the distance to the mini-cat is such that you can barely get a socket in there.

It took some frankenstein contraption of wobble head sockets and extensions to get them off.

Godspeed!.
 
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Do yourself a favor... Remove the drivers side fenders entirely. It makes the process of changing out the cats so much easier.

I did it once with the fenders on and it was a fucking nightmare and a half... I kid you not. with the fenders off on the drivers side, it makes things much more accessible, seriously.
 
I just did this last weekend. I sprayed the bolts w/ PB blaster each night for a week and bought a 15mm swivel socket.

Actually wasn't as bad as I had imagined. I spent more time trying to line up and size the adapter pipe to reach the muffler than the actual cat.
 
Got a code fore another O2 sensor. The last one was tuff because the bung hole was rusted and the new sensor barely held on. I was thinking about replacing the whole system this go around.
Anyway, what's a plug anti-fouler? I'm a diesel mechanic, so this is not my bag.
Is it better to replace the whole system with stock?
BTW, I live in the communist state of Maryland where we test.
 
Anyway, what's a plug anti-fouler? I'm a diesel mechanic, so this is not my bag.
Is it better to replace the whole system with stock?
Probably best to ignore the advice about bypassing the emissions controls with plug anti-foulers and hollowing anything out. If you have a leak you'll get a code. I'd check for any evidence you have a leak near the sensors and work on that. I've done the whole cat assembly on mine and I don't have any special tools but not too much rust either so that's a thing.
 
Probably best to ignore the advice about bypassing the emissions controls with plug anti-foulers and hollowing anything out. If you have a leak you'll get a code. I'd check for any evidence you have a leak near the sensors and work on that. I've done the whole cat assembly on mine and I don't have any special tools but not too much rust either so that's a thing.
I plan to replace the worn / rusted system from the manifold to the tailpipe with the mini cats and o2 sensors.
Just not sure about whether to use a cool aftermarket or use all stock / oem.
 
I plan to replace the worn / rusted system from the manifold to the tailpipe with the mini cats and o2 sensors.
Just not sure about whether to use a cool aftermarket or use all stock / oem.
Aftermarket stuff is pretty good these days. I used an OEM down-pipe because I had to but a good welder can work with anything. I wouldn't worry about performance when deciding, either route will work great.
 
You need a few different socket extensions and combined with a ring spanner mine was off within 20-30mins. It's tight but do-able.

I'm running the Magnaflow replacements (actually the whole system now) can't fault them apart from initial price.