Hello to all the Honda guru's out there. First, thank you for your time. So I've replaced the cats before but this time I just cant seem to stop an exhaust leak happening with the connection at the front of the cat converter that connects it to the exhaust manifold. The doughnut is in there and I've tightened the two flange bolts as far as they go and still a leak can heard. I'm told this leak would be enough to get a fail on smog. Any help or suggestion would be greatly appreciated.

 

Try a bigger donut gasket, or spray it with copper high temp sealant.

 

What header? OEM doughnut? Does the doughnut fit snug or hangs loose?

 

As well, it should be spring bolts used on the header to catalytic converter flange connection.

You probably need a new flex (donut) gasket.

Also, what year, make, model and trim car are we talking about here?

 

As stated above, should be springs on the bolts and the donut could use extra sealant sprayed on it if it won't hold. Unless it's not the gasket that's leaking, but a hole in something.