Minor exhaust leak from catalytic converter flange

[rjkoop]

Have a minor exhaust leak from the connection from the downpipe to where is connects to the catalytic converter. I'm thinking I'll trying to remove the bolts, clean the surfaces, apply high temp sealant and bolt it back up.

Or does a gasket go there?

[azruss]

no gasket

[rjkoop]

no gasket

K. So should I use sealant or no sealant and just ensure flatness of surfaces and bolt together?

[azruss]

If your surfaces are beat up, then you may have to use a sealant to stop the leaks

[MrJD]

No gaskets? Mine dont have gaskets and I planned to buy some...

[redcars]

Nope no gaskets. I used RTV copper on mine and I have no leaks. I made new end plates and welded a 2" exhaust pipe to them to replace the cat.

[WYSpider]

Nope no gaskets. I used RTV copper on mine and I have no leaks. I made new end plates and welded a 2" exhaust pipe to them to replace the cat.

+1 on RTV Copper and no leaks.

[rjkoop]

K. RTV copper it is!

[rjkoop]

Looking at this issue again. How easy it is to remove the nuts/bolts that hold the catalytic converter on? I've sprayed with penetrating oil but they seems rather rusted on. And it looks like the nuts are on the inside of the converter.

Do I loosen from the outside...


... or from the inside...


Looks impossible to get a wrench if I need to loosen from the inside. Maybe you need to bend the flange of the catalytic converter out of the way to get a wrench on those bolts?

I just want to fix the leak and not have a hugely expensive exhaust repair.

[4uall]

being that we do not require e tests for our cars I had mine removed and had a straight pipe put in to the muffler Had the guys at Midas in Bells Corners do it with zero issues since May 2012

[rjkoop]

So confirmed that the exhaust leak was coming out of the cat.

So I think a straight pipe is in order (no emissions for these older vehicles here). Looks like I don't have a resonator. Here's a few pics.







Seems to be only exhaust header, down pipe, cat, pipe up and then muffer on back.

Thinking about cutting the pipe just before the cat (cut the bolt out too - what's that for anyways?) and just before it starts to turn up. That's the only major rusty section anyways. Is this a job I can do myself without a torch to cut? I'm thinking a straight pipe, pipe hanger where the cat is now and then a flex pipe for the final section. Or maybe a muffler shop wouldn't charge much for this?

[DieselSpider]

The bolt prior to the CAT on the older cars is usually a plug for inserting an exhaust gas analyzer probe for reading fuel ratios because you will get false readings if you take them after the CAT has done its thing such as at the tail pipe. I still have my 1970's exhaust gas analyzer however the lambda probes and computers on the new cars make it mostly obsolete.

[Nanonevol]

I'm piecing together an exhaust system including a 3 bolt "cat delete" or "test pipe". I bought 2 gaskets with a silver foil appearance. Call me dense but I need to hear it again...I would do better to assemble without these and use some RTV copper? (apology for the thread hi-jack).