331 valve pan leak

[Larry Cerciello]

I have changed the valve pan gasket twice on the driver side of my 53. Now it's leaking around the top two pan screws. Is this a common problem with this motor? What is a good fix? Thanks!

[Philippe M. Ruel]

I assume this is about a valve cover gasket.

First thing to check is valve cover condition - bent, warped, rusted, cracked, torn. Warping may be hard to visualize : put the cover on a known flat surface (marble table, window glass) and try to insert a calling card in between at various places. 4 screws only on these engines may not be enough to compensate for warping.

A very thin coat of gasket paste (sealant ? compound ?) may be applied with finger on both sides of cork gasket to compensate for tiny rust crevices.

[Caddy Wizard]

Perhaps the screws have been overtightened and have dished the valve cover in the region of the screws.  Remove, flatten with hammer and dolly, reinstall with new gaskets.  My favorite brand of valve cover gaskets is the Best Brand (can be purchased from Olson's or elsewhere)...

[35-709]

If the valve cover screws have been over tightened and the holes deformed, they must first be fixed as Art Gardner stated.  Often the first attempt to stop a valve cover leak is to crank down the valve cover screws good and tight, that usually just makes it worse, sometimes this is done upon initial installation --- mistake.  It is worthy of note that the torque value called out for the 472/500 valve covers is 30 INCH pounds --- and yes, I use an inch pound torque wrench to tighten mine.  Some aftermarket valve cover gaskets call for 40 inch pounds which I comply with if that is the case.  30 to 40 inch pounds isn't much but should be all that is required.  Can't imagine that the 331 valve cover specs would be much different.  A light coating of hi-temp silicone on both sides will help with valve covers that have become a little warped over time.

If you put your valve cover on a known flat surface (such as a piece of glass) and look for any gaps, you might see where some careful massaging is called for.     

[Jay Friedman]

Once you have the valve covers straightened out and flat, my suggestion is to only put any gasket adhesive on the valve cover side.  If you put them on the cyl. head side it makes the covers hard to get off and then there is a mess to scrape off the top of the head.