OBDII exhaust manifolds

[Joe G]

So I'm running obdii manifolds and they are leaking. I thought the holes between 2 & 3 and 4 & 5 were the cause of said leak, so I fabricated 2 plates to cover them. After several test fits i have them on perfectly and completely seal the holes. But now the area where the manifolds bolt onto the block directly above the holes is the source of a new leak.

You can see/feel the exhaust escaping from there. Granted its not nearly as bad of a leak as before, but its still driving me nuts. Do need to get some new OBDII exhaust manifold gaskets?

[hoveringuy]

You may have the wrong gasket for those manifolds. The usual fix is that you weld-up the slot from the back side and flat file it to match the head.

[328ijunkie]

Which gaskets are you using? You can use a blockoff plate or weld the hole just fine as long as you keep using the OBD2 gaskets and assuming the mounting flange isnt warped.

[Joe G]

Idk what gaskets. I'm assuming they are the wrong ones, cause it's leaking from the gasket area since I installed blocking plates.