Exhaust leak at the h-pipe/header flange

[Rebel79]

I have a 97 Saleen S-351 that came with off-road exhaust. I am having to put the stock h-pipe on for a while, and I am having some major problems with the passenger header flange.

I know Mustangs, especially SN95s, have exhaust leak issues at the passenger header flange. I have done anything and everything to resolve the exhaust leak, but it doesn't go away. The leak is REALLY bad, and renders the car undriveable. Any ideas? Is there anything I can do to ensure a good seat between the header and h-pipe flange?

 

[Rebel79]

Why was this moved to a 4.6 forum, when the car/chassis/motor are all based on the 94-95 5.0?!? The h-pipe/header problem is primarily found on 94-95 mustangs, as the header flange was changed out to a flat gasket after '96.

 

[COramprat]

Because it is a 97 someone figures it should be 4.6. If the swap is temporary maybe use some high temp RTV to get a good seal? I did that with my 96 with the flat flange. I assume your flange is the bell type?

 

[Rebel79]

Yeah its the bell flange. Now I am not so sure it is coming from the flange... the leak seems to be coming around the header. I have Stage 8 locking header bolts, all of which are tight.

 

[COramprat]

Hmmm...maybe a crack? If it is loud though you'd probably see it. Sounds like you may have to pull the header.

 

[HISSIN50]

If you don't have access to a smoke machine, a little seafoam in a manifold vac line can help you find the leak.

 

[RIO5.0]

Is it leaking where the EGR tube connects or the tube itself cracked??

With those bolts you have plenty of lenght. double up on the gasket, thats how I run mine as I was getting some noise too...double Fel-Pro 1415 I believe.