Finding solution to leaking valve cover gaskets...

[Tony Tee]

1970 charger with a 383. I’ve taken the valve covers on and off and changed gaskets about 6 times now and I’m looking for this next time to be the last.

both valve covers were leaking from the rear of the block by the firewall so I pulled them off and replaced them with the cork gasket. That didn’t work so I tried a better gasket (fel pro rubber/cork). Same issue. Tried the moroso perm align gaskets. Nope! Put RTV on both sides of the gasket. Same issue! Took valve covers off and switched the sides with a new gasket with RTV. No luck. The leak only kind of slowed down. And I’ve always cleaned the head surface with acetone and made sure it was nice and clean before continuing.

I redid my valley pan gasket thinking that maybe that was the issue. It wasn’t but now I have a new valley pan gasket that doesn’t leak. I’ve inspected the valve covers and they’re straight. They’re the aluminum mopar performance ones. And I’ve properly torqued them down. They’re not too tight at all. A little bit past snug.
Any suggestions here? I’ve always heard you shouldn’t have to put RTV on the valve cover gaskets and I never have done it in the past. Just wondering where to go from here. Any help would be appreciated.

I had a 440 that always leaked on the passenger side by the exhaust manifold. Found out that there was a dip in the cylinder head cast iron. Had to remove the head and had it milled to get it all level . Leak fixed ! So check all the mating surfaces with a straight edge.

 

[Macdon221]

Had the same issue on the passenger side only near the rear.....tried everything. Found this post...

https://www.forbbodiesonly.com/moparforum/threads/valve-cover-gaskets.87565/#post-910218941

Did as DVW said in post #14. Fixed it first time. No leaks at all after that.

 

[lochenjons]

What a busy weekend, I had some time to pull the covers and see what’s going on. The gaskets were dry except for around where the bolts go on the last 1/3 of the head - towards the rear of the motor. I checked the level of my valve covers with a straight edge and they were fine. I checked the head and sure enough. They’re off. Considerably. Pulling the heads is not an option as I’m going to replace or rebuild this motor some day when I have space to do so (right now the car sits outside and it’s a PITA to do any big jobs). A friend of mine suggested either using two thicker gaskets (I have the rubber/steel felpro’s now) or using a cork and a rubber gasket together. I might try that first before I use the right stuff. Unless anyone has a recommendation for a thicker/softer gasket?

 

[lochenjons]

Update: I really don’t want to use any kind of sealant but it looks like it’s going that way. A friend suggested using a cork and my felpro gasket together. So I put the cork on first, then the felpro, then the valve cover. It’s still leaking. Not AS much but when I touch the back of the head I get oil on my fingers. Looks like I’ll be doing the weatherstripping adhesive method

 

[origcharger]

I generally have luck gluing the good cork gaskets to the cover and snugging down, expect to have to re snug them down several times after multiple heat cycles.
As said some of the heads have horrendous VC sealing surfaces and may even leak worse with rigid cast covers than they did with the stamped steel ones.

 

[andyf]

Both the valve covers and the head need to be flat, smooth and rigid. If they are both flat, smooth and rigid then it is easy to seal without leaks since it is a very low pressure system. If they aren't flat, smooth and rigid then you'll have leaks. I ended up making my own valve covers to solve the leak issue. That fixed it. Haven't had a leak in years and I can reuse the gaskets over and over.