I just discovered that my newly installed intake manifold gaskets are leaking coolant and my idle is real rough.  Is it advisable to use gasket sealer on these gaskets and  if so what would be a good sealer to use for this?   This is a 239 Y-Block.  Thanks. 

I normally use only white grease on both sides of the intake manifold gaskets.  Setting the intake down without the gaskets on the torqued in place heads and looking down the sides of the manifold from the front and rear will verify that the angles are correct.  Dry fitting the gaskets on both the heads and intake before actually installing them will verify that all the pertinent holes do align properly and will give the best chance for sealing.  If the heads and deck have been heavily milled, then the possibility exists that the manifold will not bolt down properly.  In these cases, the intake side of the heads or the gasket sealing side of the intake manifold will need to be milled. 
 
If I do use sealer, it’s typically CopperCoat®.

Lorena, Texas (South of Waco)

OK Ted I will follow your instructions and hope for the best.   The intake never leaked before taking off manifold so probably just bad installation.  Thanks again.......Whipper  Bill

I use the copper/orange colored RTV around the water passages.  No leaks.


54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ