So… I replaced my exhaust manifolds with a repop set from OPGI (manf. By cpp). They fit really well but I am having a hard time getting the exhaust pipes to seal up to the flange joints. The tapered connection joint is machined into the manifold and is more like a big chamfer than the radius that is cast into the factory manifolds. I loosened the exhaust hangers to neutralize the exhaust pipes and mated them up and re-torqued them and they still leak. Just wondering if anyone else has used these or any ideas to seal them up. I really don’t want to take the manifolds back off.

 

I know Joe uses the Acoustic seal on exhaust joints. I use Permatex Optimum Grey. Extremely robust and very flexible. Being Grey, it is nearly invisible. Make sure there is no burrs on the pipe or manifold outlet. Good luck.

 

Sorry to hear your issue what about using a flange gasket?

 

Thanks for the suggestions. I will try the Permatex, just have never had to before.

 

Just curious.....are your downpipes stainless, I have found that stainless pipes don’t conform as easily.

 

Iirc the originals had 2 different size flanges 2.25 and 2.5”. Is it one of both sides that wont seal? Are the repops 2 different sizes?

 

They are both 2.250”. The pipes are aluminum coated steel and the system is relatively new.

 

I guess I should have mentioned it is a dual exhaust system with no crossover.

 

When i take it apart again I will take some pictures so you guys can see what I am dealing with.

 

I've used this for over 40 years.

Walker Exhaust 35958 Pipe Cement

 

I like Walker Acousti Seal.

 

Finally got it sealed up by carefully realigning the exhaust and using high temp silicone. Wasn’t able to get any pics of the manifold flange. Took it on a long road test and so far so good. Thanks for all the suggestions.

 

Thornton makes the down pipe to match the manifolds. The repo manifolds are 2.5 outlets. That's why you are having the problem.
Or your local muffler shop can make you a 2.5 pipe.