Return to ForumsReply to Thread
79 vette

I have a 79 vette 383 stroker. For some reason I can't seem to solve a problem with leaking valve cover gaskets. The leak is coming from the left rear of the engine. The gaskets have been replaced several times within a short period of time.

Submitted by: Kelvet Talley


ReplyPosted By
I have had similar issues myself. Are the cylinder heads the old style with perimeter (4 bolt) attachment or the newer center bolt attachment covers? My experience is with the perimeter bolt valve covers, namely the aluminum LT1/L82 aluminum valve covers. Mine also weeped at the lower rear of the covers which is the low spot where oil accumulates. First off I used the Fel Pro double thick cork valve cover gaskets that use a steel core to reinforce the thicker gaskets, they are 5/16" thick. Next make sure you thoroughly clean the valve cover rails on the cylinder heads and the mounting surface on the valve covers themselves. I use alcohol. Get a can of Permatex "High Tack" which comes in a spray can. Spray the valve cover surface and then spray the gasket on one side. Wait about 3 minutes for it to "tack" up and attach the gasket to the cover. Then spray the cylinder head rail and the other side of the gasket (attached to the valve cover) and assemble to the engine. Overspray can be cleaned with alcohol or carb cleaner, or sometimes brake clean will work. You will need longer bolts to attach the valve cover which you can get at most hardware stores. Use SS if they have them 1/4x20/1.25. I also use a star washer and then a flat washer under the bolt head. I don't use a torque wrench, just snug them down fairly tight using a 1/4 drive. Let the whole thing sit overnight, then start it the next morning. It should be sealed and you may want to hand tighten the bolts again after it warms up. This basically glues the covers to the head rails, and they don't come off easy, but if you use a putty knife, you can break the seal between the gasket and the head if you need to remove them again, that's what I end up doing. Now I imagine that your cylinder heads are some sort of aftermarket heads like mine and have a machined rail surface where the valve cover attaches. If you are using older Chevy OE heads from the 60's and 70', the rails are just "as cast" and very porous. They are very difficult to seal, and I was never able to get them to quit weeping until I installed newer heads. Again, I did this procedure with the Chevy perimeter bolt aluminum valve covers, but it should work with the center bolt aluminums as well. If you are using the steel valve covers, it may work better with the standard Fel Pro cork gasket using high tack and the spring bars, but I can't vouch for it. I hope this helps and good luck. D on 4/4/2016 9:27:52 PM
The type of gasket makes a big difference. If you’re using old fashioned cork gaskets --- good luck. But if you’re using modern composite gaskets you should check for porosity in the sealing surface of the head. Using a machinist’s straight edge, check the sealing surface of the valve covers to make sure the covers aren’t warped from over tightening and yes aluminum warps when improperly tightened. If everything is mechanically correct it comes down to something you’re doing wrong. One very wrong thing that do-it-yourselfers and techs alike do is begin adding RTV or some form of gasket akum-pucky to seal something that doesn’t need and shouldn’t have sealant. Unless there are specific instructions with the gaskets do not add sealant of any kind to a gasket as it will almost always cause leaks. Then of course there are those who think if a little bit is good a whole lot is a whole lot better. In this case I’m talking about torque. Using an inch pound torque wrench torque the valve cover bolts to 36 to 40 inch pounds or slightly more than finger tight. Finally, if the valve covers are steel make sure they have the proper torque spreaders on the bolts to even out the force applied by the bolts. Posted by Administrator on 2/29/2016 4:23:41 PM
Do you have the stock or after maket valve covers? Are they vented,pcv valve or vent.with out these there will too much pressure Henry Callahan on 1/7/2013 1:23:14 PM
Either your valve cover or your head is not straight - probably the cover. Straighten it if you can. Plan 'B' would be to use the rubber gaskets with the black gasket cement on both sides. Be sure both the head and cover mating surfaces are oil free. Arthur Knigge on 8/17/2012 3:44:39 PM

Return to ForumsReply to Thread