Persistent leaky valve cover on LA

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Bill Crowell

Bill Crowell

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Original sheet metal factory valve covers, which are clean. Using the Moroso hold-downs. I really don't want to have to permatex the valve cover to the cylinder head, not only because it is redneck, but also because it is so hard to get the permatex off later when replacing the gasket, and because you can't avoid getting some of the permatex into the pushrod holes when you scrape it off the head.

I tried straightening the valve cover and so did my mechanic. He thought he got it straight, but it still leaks. Would you guys have any words of wisdom for me before I buy some alloy valve covers?
 
What worked for me was sealer on gasket to the valve cover and stop tightening the bolts like they were lug nuts
 
Glue it to the cover then softly tighten the cover down finger tight. Leave over night. Then tighten the rest of the way very lightly. A small dot of sealer on each bolt. You can remove and replace after that a bunch of times without replacing.
 
Glue the gasket to the VC with 3M 08008 super weather strip adhesive, after it sets up it will never leak between the VC and the gasket. 1/2 the battle is over.
 
I have always only put sealant on the removeable part. Timing cover, water pump,whatever.
Grease the side you dont want to stick.
And valve covers no tighter than a nut driver. Even then may be a little much. May want to look closely for a crack too. BTDT
 
Tooljunkie said:
I have always only put sealant on the removeable part. Timing cover, water pump,whatever.
Grease the side you dont want to stick.
And valve covers no tighter than a nut driver. Even then may be a little much. May want to look closely for a crack too. BTDT
Click to expand...
Grease is the ticket.
 
Are the covers hitting the intake? Sometimes that will make them leak.
This is how I do it. I only use the stock cork ones. the flanges and head surface have to be 100% clean of all grease and oil, including from your skin. Use a small amount of weatherstrip adhesive to glue the gasket to the tin cover. Place the cover in place, and start all the bolts by hand. Then, using a 1/4" drive wratchet and extension so you are really only using your wrist to torque them, start with the center bolt on the bottom. Snug it down but not fully. Then do the two lower corner ones. Then snug all three lower bolts up. Then do the two top bolts the same way. Snug them both, then tighten using only your wrist and the small wratchet. If the cover bends, you went too far. Doing them this way for 35 years - rarely a leak. Plus I've reused the same gaskets for years doing lash adjustments.
Three main causes for leaks: oil or grease on the mating surfaces, the gasket is too stiff, or the fasteners were overtightened.
 
check the head for core shift could have a low spot on vc sealing surface I have seen this on some
 
Amen to that ! Spotlessly cleaned surfaces bone dry to start off with. Cork gaskets adhered only to the cover. Bottom bolts snug .Then tops .Never over tighten. And make sure PCV valve is rattlely while you are at it.
 
Search box at the top would also give you about 35 other tricks and tips to stop the leaking too.
 
Check the breather/PVC system, had a similar problem on a 440, added (read replaced) the breather and it was good.
 
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