Got a '79 f-250 351m was leaking out of the valve cover gasket replaced old rubber with new cork gasket now it appears to be leaking from a new spot. It tends to only leak at high rpm also. can this be solved by pulling the gasket and putting some rtv down first???

 

Welcome to FTE. You for sure want to tack it down to the valve cover with a light bead of RTV. Whether or not you put a bead on the cylinder head flange is up for debate, I'd try it without first. The important thing is that you torque it down gently and evenly to specification, without overtightening. If the valve cover flanges are not flat, they won't seal. Big thing to remember with a cork gasket is that you have to re-torque it a couple times after it sits for a little while each time, because the gasket will relax. If you didn't do this the first time, that may be why it's leaking.

 

good deal, i'll check tightness. thanks

 

also if you continue to have problems with your cork gaskets leaking and for some strange reason the RTV doesn't stop any leaks another option would be to yet again get a new set of gaskets and some gasket sealer I have found even though a valve cover gasket should be oil resistant some manufacturers are cheapskates and they aren't so the sealer helps a bit

 

I always use a thin coat to glue the gasket to the valve cover, just put it on your finger and spread it on 1/16 thick or so over the whole gasket. Never had one leak even with cheapo taiwanese chrome covers on a chevy. Makes installation a lot easier too.
-Johnboy

 

Ive always put it on the head instead of the valve cover. Never had a leak.

 

I would lay odds on the valve cover flange being bent or otherwise distorted. If they were previously overtorqued they may naver seal until they are repaired.
I hate scraping the old stuff off and never use any type of sealant. Straight covers, even stamped steel ones will seal fine if they are straight.