Exhaust leak after installing primary cats

[KingCarGuyZ]

Alright, so I just spent 2 days fighting rusty bolts and heavy objects to replace the Jeeps primary Cat’s. Go to test start her tonight and it sounds like a tractor the leak is so bad. The Cat I bought (Eastern Catalytic from Rock Auto) came with the exhaust gasket for between the primary and secondary cats, I cleaned the surfaces and installed it, fairly sure the leak isint coming from there base diff of echo-location. However the cats Came with nothing for between the header and the primary’s. According to my research through parts diagrams YJ’s and TJ’s had “doughnuts” up until about 2000 when they dropped off the parts diagrams and there is no PN for it.

from what I can tell the exhaust Leak seems to be coming from the header/primary junction I have “re-set” the clamps several times and painstakingly insures that they are even on both sides (one click here one click there) anyone have any idea what could be the problem? Do I need doughnuts after all ? Anyone know where to get them?

oh and just for reference she’s a 2001 Sport 4.0 5spd.

 

[TJ4Jim]

Alright, so I just spent 2 days fighting rusty bolts and heavy objects to replace the Jeeps primary Cat’s. Go to test start her tonight and it sounds like a tractor the leak is so bad. The Cat I bought (Eastern Catalytic from Rock Auto) came with the exhaust gasket for between the primary and secondary cats, I cleaned the surfaces and installed it, fairly sure the leak isint coming from there base diff of echo-location. However the cats Came with nothing for between the header and the primary’s. According to my research through parts diagrams YJ’s and TJ’s had “doughnuts” up until about 2000 when they dropped off the parts diagrams and there is no PN for it.

from what I can tell the exhaust Leak seems to be coming from the header/primary junction I have “re-set” the clamps several times and painstakingly insures that they are even on both sides (one click here one click there) anyone have any idea what could be the problem? Do I need doughnuts after all ? Anyone know where to get them?

oh and just for reference she’s a 2001 Sport 4.0 5spd.

Some exhaust headers I have had experience with either have a thin stub pipe that a doughnut will slide over or an actual beveled doughnut formed in. I always use a coat of high temp anti-seize on the surfaces (and bolts) so the joints seat properly, seems to help a lot.

If you need a doughnut (like the lead wool type) they are very available at most auto parts stores.

 

[dbbd1]

I can't recall the exact circumstances but another forum member had a replacement exhaust section where that little stub was too long. As a result, it was not seating fully.

 

[KingCarGuyZ]

I can't recall the exact circumstances but another forum member had a replacement exhaust section where that little stub was too long. As a result, it was not seating fully.

Like the stub from the header?

 

[TJ4Jim]

What Is the downpipe connection on your header.

 

[KingCarGuyZ]

What Is the downpipe connection on your header.

here’s a picture, of the connection, that’s the new cats “installed” but still leaking

Here they are side by side out of the jeep

other then that, hard to say. Seems as though the header slips into the cat and then u tighten the bolts so it’s snug.

 

[KingCarGuyZ]

So update, it appears to be a DOA part, the front most cat was welded at the incorrect angle to mesh and seal with the header. Now I get to work out rock auto returns or try and borrow someone’s welder and fix it. Guess I shoulda sprung for magnaflow.

I’ll try and provide more detailed pictures when I get the old cat and the DOA cat in the bench for comparison.