Exhaust Leak Problem

[ziggy428]

Ok, so I was just giving my truck a little attention to get the MPG's up to normal. Its had an exhuast leak so I torqued all bolts and tried to change the cat-converter gaskets. After trying Advanced, Autozone, and checker I found all the gaskets to be at least 2-5 mm to small to fit on the flange. What am I doing wrong? Flange is around 60mm but i.d. of the gaskets was from 55-57mm. I cut half of the inside out of one that has coiled layers of green asbestos or whatever it is. I wound the rest around the outside. Truck sounds really quiet now, no roaring or hissing until high rpms. Only problem is it starts hard like similar to cold weather starting. Is this a dealer only item and whats with the starting?

[tacotoy]

i would have used some of the high quality exhaust tape.... pretty much the same material as the asbestos gasket just with some high temp adhesive.... cut to fit to make your own gasket. and usually cheaper and you dont have to wonder if the gasket slipped down....

as for the starting i dunno... try resetting your ecu? depending on where your leak was the o2 sensor might be freaking out.

[ziggy428]

i would have used some of the high quality exhaust tape.... pretty much the same material as the asbestos gasket just with some high temp adhesive.... cut to fit to make your own gasket. and usually cheaper and you dont have to wonder if the gasket slipped down....

as for the starting i dunno... try resetting your ecu? depending on where your leak was the o2 sensor might be freaking out.

I may try that if nothing else works. Wondering if part of the gasket might have gotten stuck in the cat causing more backpressure. I've reset the OBD and EFI but no change. One thing I might check is I replaced the upstream O2 sensor but not the downstream, (might try using both old ones.) I'm pretty sure the only place left its leaking is downstream cat to muffler flange.
Thanks for the advice.

UPDATE: Seems like the ECU's been adapting, starts somewhat better now. If the gasket won't hold I'm going to try the muffler sealer/copper rtv sealant and make my own out of a couple layers of thin aluminum. Not sure how that will work.