Exhaust leak from X Pipe to Catback
Thread Starter
Drifting
Joined: Jul 2006
Posts: 1,373
Likes: 33
From: Shelby Township MI
Exhaust leak from X Pipe to Catback
Any ideas on how to cure this? I have the same leak on both sides were the X pipe connects to the catback.
I'm thinking new gaskets and using copper sealant on each side. I also may belt sand both surfaces to try and make them flatter.
I installed XS Power headers to my Ti Catback two years ago and has been leaking from day one. I did use new GM gaskets. To me it locks like two surfaces on not flat, or maybe my catback is cocked.
I'm thinking new gaskets and using copper sealant on each side. I also may belt sand both surfaces to try and make them flatter.
I installed XS Power headers to my Ti Catback two years ago and has been leaking from day one. I did use new GM gaskets. To me it locks like two surfaces on not flat, or maybe my catback is cocked.
Safety Car
Joined: Aug 2011
Posts: 4,437
Likes: 404
From: Portland OR
Looks like one or the other flanges is not flat. I had to sand my catback, they were warped. I also have the XSPower setup.
Permatex orange silicone or any high temp sealer will work. Those GM gaskets are expensive, you might be able to re-use yours.
Permatex orange silicone or any high temp sealer will work. Those GM gaskets are expensive, you might be able to re-use yours.
Tech Contributor
Joined: May 2008
Posts: 3,100
Likes: 17
From: Somers, CT and Clermont, FL
St. Jude Donor '09-'10-'11-'12-'13-'14-'15-'16
Use two OEM gaskets on each flange connection, and coat both sides of each gasket with copper sealant.
Your old gaskets will be fine to reuse, so you will only need two more new ones.
Your old gaskets will be fine to reuse, so you will only need two more new ones.
Melting Slicks
Joined: Jun 2012
Posts: 3,163
Likes: 6
From: Oceanside California
I used copper gasket maker to fix the leaks from this area. Its holding up fine.
Pro
Joined: Aug 2012
Posts: 568
Likes: 1
From: Fresno California
This is what we did for a friend who kind of has an OCD issue with this problem.
First we flattened both flanges. We then cut two 1" long pieces of stainless pipe, split them length wise and ground the edge until they press fit into the axle back. We welded the split back together to make a ring that fit inside the axle back and mid pipe. We pushed half the length inside the axle back pipe and tact welded them in three places. You have to make sure they will fit inside both pipes. We had to do a little grinding and smoothing to make sure they fit into all four pipes by 1/2" when bolted together. We had new gaskets but did all of this because we wanted to be sure it never leaked again. That was about 4 years ago and about 4 tear downs ago and it has never leaked a drop.
It may be overkill to some but different situations have different requirements.
I just let mine leak because from what I can see it is just condensation that collects there overnight. I have had a good look at them with the engine running and couldn't detect any exhaust leaking out.
First we flattened both flanges. We then cut two 1" long pieces of stainless pipe, split them length wise and ground the edge until they press fit into the axle back. We welded the split back together to make a ring that fit inside the axle back and mid pipe. We pushed half the length inside the axle back pipe and tact welded them in three places. You have to make sure they will fit inside both pipes. We had to do a little grinding and smoothing to make sure they fit into all four pipes by 1/2" when bolted together. We had new gaskets but did all of this because we wanted to be sure it never leaked again. That was about 4 years ago and about 4 tear downs ago and it has never leaked a drop.
It may be overkill to some but different situations have different requirements.
I just let mine leak because from what I can see it is just condensation that collects there overnight. I have had a good look at them with the engine running and couldn't detect any exhaust leaking out.
Last edited by onlyavette; Feb 10, 2013 at 10:27 PM.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
2027 Corvette Buyer's Guide: Everything You Need to Know!
Joe Kucinski
Team Owner
Joined: May 2006
Posts: 21,473
Likes: 356
From: Palmdale, Ca----- 2009 Cyber Gray 4LT A6 F55 452 RWHP 422 RWTQ- RIP 1998 C5 734 RWHP & 585 RWTQ-----
"IF" you belt sand make sure you be careful on the Titanium side and use plenty of good ventilation and mask for particulates! 
Or use Copper Hi-Temp gasket sealer - that will work for sure!
Thanks,Matt
Or use Copper Hi-Temp gasket sealer - that will work for sure!
Thanks,Matt
Thread Starter
Drifting
Joined: Jul 2006
Posts: 1,373
Likes: 33
From: Shelby Township MI
This is what we did for a friend who kind of has an OCD issue with this problem.
First we flattened both flanges. We then cut two 1" long pieces of stainless pipe, split them length wise and ground the edge until they press fit into the axle back. We welded the split back together to make a ring that fit inside the axle back and mid pipe. We pushed half the length inside the axle back pipe and tact welded them in three places. You have to make sure they will fit inside both pipes. We had to do a little grinding and smoothing to make sure they fit into all four pipes by 1/2" when bolted together. We had new gaskets but did all of this because we wanted to be sure it never leaked again. That was about 4 years ago and about 4 tear downs ago and it has never leaked a drop.
It may be overkill to some but different situations have different requirements.
I just let mine leak because from what I can see it is just condensation that collects there overnight. I have had a good look at them with the engine running and couldn't detect any exhaust leaking out.
First we flattened both flanges. We then cut two 1" long pieces of stainless pipe, split them length wise and ground the edge until they press fit into the axle back. We welded the split back together to make a ring that fit inside the axle back and mid pipe. We pushed half the length inside the axle back pipe and tact welded them in three places. You have to make sure they will fit inside both pipes. We had to do a little grinding and smoothing to make sure they fit into all four pipes by 1/2" when bolted together. We had new gaskets but did all of this because we wanted to be sure it never leaked again. That was about 4 years ago and about 4 tear downs ago and it has never leaked a drop.
It may be overkill to some but different situations have different requirements.
I just let mine leak because from what I can see it is just condensation that collects there overnight. I have had a good look at them with the engine running and couldn't detect any exhaust leaking out.
Burning Brakes
Joined: Jun 2012
Posts: 1,240
Likes: 1
From: Orange County California
I also bought the 3" sealer band clamps from pep boys, slathered them in that same High Temp Gasket maker, and got rid of those C clamps that came with the system for the slip fit mid-pipe connection
was leaking there before too, not now.
Melting Slicks
Joined: Apr 2009
Posts: 2,479
Likes: 36
I've done this numerous times. Using two gaskets usually solves this issue. This also depends on the gasket quality. Some gaskets are better than others.
Or, buy gaskets with the embossed raised copper bead. It increases sealing pressure on the inside diameter of the pipe. These are excellent for sealing imperfect surfaces. They cost a little more but are completely worth it.
PS: I wouldn't worry too much about condensation drips. This does not necessarily mean that you have a leak. But, black soot does which is the case with the OP.
Last edited by Cybermind; Feb 11, 2013 at 07:22 AM.