I replaced the catalytic converter on my 93 Miata with a test pipe. The issue is there is an exhaust leak that I can't seem to fix. I tightened the flange all the way around and it still leaks.
It only leaks from one side and at first it leaked from below the pipe but after flipping the gasket and re-tightening it now leaks from above. I tried to buy a new gasket and had the same issue. I spent more than an hour around that flange and tightened it as best as I could but it still leaked
Is it safe to use RTV to get rid of the leak? Otherwise how can I fix this problem?
Update: I used 2 gaskets and the leak improved but it was still there. One thing that came to mind is I didnt clean the mating surface of the pipe, is that something that should be done to exhaust flanges as it never occured to me?
If so how is it done properly?