Creating a clamp/union just prior to catalytic?

[eightynine4x4]

1989 2.9l 4x4 automatic

Long story short: I’ve got a bad connection from Y pipe to cat.. the old Y pipe has rusted away a little bit at the very end and so the gasket doesn’t even really seat since there not enough metal around it.
So I have a leaky connection there, and it’s visibly releasing some pre-cat exhaust.

Also, I can’t replace my whole Y-pipe without shutting down the truck for a couple weeks and working on removing the left exhaust manifold. I already replace the right and it was been tremendously precarious and a huge waste of time. Almost had to ditch the truck project. So I’m not going to commit to fully replacing the Y pipe any time soon because I am not touching that left manifold right now.

A compromise..
what about buying a new Y pipe and cutting it like a foot upstream from the cat, and replacing just that section of old Y pipe? Would a dual clamped sleeve around the y pipe(s) juncture be enough to seal the new segment to the old Y pipe? Talking about using a short strip of tubular metal that barely slides over both now exposed ends and using two u-clamps, one for each half of connection.

Sound like a terrible idea for any reason? In the distant future I could even use the rest of the new Y-pipe once I removed the left exhaust manifold. It would clamp together prior to the cat in the same fashion. Might look a little weird but if this sets me up to stop the leak then I’m happy. Wouldn’t care about always seeing a union there in future too.

 

[franklin2]

Your idea sounds good, but I would take it to a muffler shop and have them weld the new piece in place. The clamps will probably leak. If I am remembering that area correctly, it's very curvy and when they bend the pipe it's not round anymore. Pipe that is not round is very hard to seal with a clamp.

 

[Uncle Gump]

Ya know... there are certain things that require just biting the bullet and paying the fella that deals with these types of things on a daily basis. I also know that some folks have more time then money.

Some exhaust shops are really good... you drop it off... pay the bill.... be on your merry way the same day. No rust in your eye... no wasted weekends... just a thought.

 

[19Walt93]

We used to buy replacement flanges from Napa and weld them on, no point buying a new pipe and butchering it.
A good exhaust shop will make quick work of it, too.

 

[4x4prepper]

I used to make my own pipes and flanges for dual exhaust from JCW supplies using MIG with 75/25. Then I ran out of gas and tried flux core, what a disaster, blew holes in the pipe even on the lightest setting. I would bite the bullet and bring it to a real muffler place and have them flange it if you can't afford to be down. You can take a flange, weld it to a section of pipe (think electrical conduit), then shove that into the pipe and clamp around it. A slathering of muffler cement would not hurt. if you have a exhaust pipe expander to use with an impact wrench (yah, they "say" not to use it) it makes the insertion much easier.

A picture of your problem would have been worth 200+ words.

 

[franklin2]

I know what he is saying about taking the manifolds off though. I pulled my engine to replace all the freeze plugs. Twisted all 4 of the exhaust outlet/y-pipe connection studs off. Fortunately I was able to drill all 4 out and use bolts and nuts instead. But then I found out one of the heads had a crack. Went to take the manifolds off the heads, broke every one of the bolts off that fasten the manifolds to the heads. I bought some new heads off ebay and had to send the old ones back, so I let them worry about the broken off bolts. So then I had hard time finding the correct metric bolts locally, finally found them at a local Napa. What a mess.

 

[eightynine4x4]

I used to make my own pipes and flanges for dual exhaust from JCW supplies using MIG with 75/25. Then I ran out of gas and tried flux core, what a disaster, blew holes in the pipe even on the lightest setting. I would bite the bullet and bring it to a real muffler place and have them flange it if you can't afford to be down. You can take a flange, weld it to a section of pipe (think electrical conduit), then shove that into the pipe and clamp around it. A slathering of muffler cement would not hurt. if you have a exhaust pipe expander to use with an impact wrench (yah, they "say" not to use it) it makes the insertion much easier.

A picture of your problem would have been worth 200+ words.

Pic below.
You can see that the cat on the far side of the connection is healthy (it’s brand new last summer) and that the flanged end of the y pipe is simply missing around the perimeter. This lets the gasket flop in the wind and let out some exhaust.
These pics are from before I replaced the gasket and also caked on a bunch of exhaust cement just to see how that performed.. lasted a while but now it leaks.

I really can’t do the left exhaust manifold for a while. The right required a very special effort that no shop would even touch. I asked a couple places. So I grunted through it and did a good job. I had to sawzall the manifold apart, while still on the truck, into 4 sections so that I could focus on “unbolting” each part in unusual ways involving ruining multiple threads. Eaxh segment was a lot of work and risky. Completely nuts. If in the future I come up w a plan to upgrade exhaust flow I will consider headers and have motivation to do the second manifold. It doesn’t leak at all, i ram some tests.
Anyways, I like the idea of dropping it off at a shop and providing the clean new segment of pipe/flange. I could just say “hey cut this here and replace it with this new segment and weld it.” But the pipe is pretty close to the underside/frame/body of the truck. Im not in front of truck until tomorrow but I vaguely remember only an inch or two free space above the pipe. Is that enough space to weld a pipe together end to end?
As for acquiring a replacement.. yeah if I’m welding then it does suck to chop and waste a new y pipe… are these flanges in some way standard? Can I just buy a flange, buy a foot of pipe, hand those to the welder and say replace this end section of Y pipe? Is the bolt pattern of flanges a common one? Is there a name to this flange style? It’s got 3 bolts.