exhaust leak

[stefan]

This is driving me NUTS! I have a horrible exhaust leak where my down-pipe bolts to my manifold and i cant fix it no-matter what i do! I've tried new gasket torqued with a torque wrench, new gasket torqued with an impact gun, I've tried that exhaust cement stuff... and my last attempt I tried silicone gasket maker, and sadly enough that lasted the longest (almost a week)

any suggestions? I dont need it to last too long, because my B6 will be going in soon... To be honest im tempted to weld the flanges together because I wont be reusing ither.

[freestiva]

if you really dont care, use j-b weld you can still take it apart later and its pretty easy to use.

[Festy46]

J-B weld worked pretty good for me on a 460 Ford, but you have to really clean the rust down to bare metal first. I put some on with just a light wire brushing and it didn't stick. You might try using 2 gaskets to give you more crush space, too.

[jglutz]

Couple of suggestions.....

New bolts or atleast clean/chase the threads on the old ones.....maybe they're tight before they should be. If I repalce exhaust bolts, I buy stainless steel at the hardware store.

One of the flanges is not flat. Take the pipe out and drag a straight edge accross both flanges. File/grind/sand as necessary.

The exhaust manifold flange must be torqued tight before the cat flange is. The exhaust manifold is rigid wher as the cat is flexible.

Maybe the pipe...cat...or pipe is blocked creating a back pressure that blows the gaskets out.

Just some ideas...hope they help.

[25Horseplay]

Another possibility is the stock down pipe is a double walled pipe, it could be rusted out on the internal pipe.