cracked precat

XJensen said:

Not going back to Muffler Tech again. flanges at the pre cat and manifold were still loose after I told them. They insisted it was cracked and described the location of the cracks to me.

My buddy stopped by and we tightened the bolts. Guess what no more leak!

sure beats the $2300 I was quoted.

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that exhaust shop is a joke. We were able to tighten those down on your rig, it was just hard to reach in to the 2 middle bolts. I bet that happens to alot of guys. Maybe wrap them in lava fiber wrap like on summit to help keep some of the heat out of the engine bay?

Also an FYI for anyone else in the same boat. The flange bolts were 15mm an a short box wrench worked best.

If you do need new per cats magnaflow does make a 50 state legal version. It was "only" $700. Still suck but way better than $1750.

Thanks for the info. I'm throwing a P0432 code now and I'm betting it's the pre-cats (actually the ONLY cats on my 2001 california market model) since in at 180k on the originals. Not sure though since if I grab the front of the muffler pipe and wiggle it I can see the cats wiggle right along with it.

Possible manifold separation?




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Could be loose bolts. My bolts were tight, the rear pre-cat was the problem.

There should be a third cat on your rig, behind the crossmember.

Changing them is not all that hard. A 15mm swivel helps. Anything else seems like you're fighting for clearance.

Just went through the dreaded P0432 code on my '00 with CA Emissions. Research seemed to say 95% of the time it is the front cat. But could be anything from fuel trims, vacuum leaks, exhaust leaks, to O2 sensors. After ruling out everything as best I could replaced the front cat. Since I needed a new muffler and tailpipe I also replaced that and everything else too. All has been good since.