New Intake manifold installation - How much RTV sealant?
 

On an installation of new intake manifolds, is sealant required on BOTH the air and water passageways?

I did just the outer corners where the water passageways were, and am experiencing vacuum seepage/leakage on a portion of the gaskets even though they are torqued to spec (22 ftlbs). I tried tightening a little more, but no change.

These gaskets were the ones ordered by ********az. Should I be looking at different gasket makes?

I've never used sealant on manifold installations, the gasket should be all that is needed. Loosen the manifold and make sure you have removed all of the old gasket material (parts of the original gasket may stick hard). Acetone can help with the removal and clean-up of the old gasket. (you don't want to gouge either surface with your clean-up tools). When installing the manifold snug the bolts up lightly then begin to torque to specs. You don't want to warp the manifold by bolting one area of the manifold down tight while the rest of it is still loose. I've used gaskets from ********az with no problems.

I'll almost second that.

I use semi-hardening sealant, if any at all. RTV is not intended to seal gaskets, and should only be used where specifically directed by the engine manufacturer. It's not designed to seal gaskets, and does not do a good job.

Indian Head gasket cement works well for most places where you want to glue the gaskets in place, but you will work when you take it back apart.

Hi - in addition to what has already been said, RTV is death on oxygen sensors, and should not be used anywhere in the intake system, especially anyplace gasoline could contact it, as gasoline dissolves it in short order. Even a microscopic amount of fumes from it will kill the O2 sensor.