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Leaking Valve Covers


mt65riv
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Got my Rivi running/driving after a 4-year hibernation.  It is great but I am having an issue that is driving me nuts!

 

Anyone have a sure fire way of sealing the valve covers?  I got my Rivi running and it is running/driving excellent but the valve covers wont stop leaking.  I have a couple sets so I took the best ones and made sure that the surface for the gasket was clean and straight.  I used the rubber type and they are leaking between the head and the gasket on the outside/rear on both sides.  Oil on the heads and exhaust isn't pleasant. 

 

Gluing them to the valve covers would not make a difference here.  I did see a post where cork gaskets were preferred but I have never had good luck with cork on any engine.

 

Any ideas?

 

Thanks! 

 

Mike

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My first thought is that you should take the covers and lay them on a flat surface to make sure that they haven't been over torqued at some time and the corners are bent.  I'd also lay a straight edge on the head sealing surface to make sure that they're straight.  I've never had a problem with rubber or cork.

 

One other thought is that perhaps the oil drain back holes are clogged and there's too much oil not draining back into the sump.  I remember that my dad would set the valve lash on the straight eights with the engine running.  There would be no valve cover in place and there'd never be any leaking down the sides of the head.

 

Ed

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I think Ed's advice is correct.  I have always used Fel-Pro rubber gaskets on my Nailheads with no issue.  Sealants are not required with these rubber gaskets.  It is easy to over-torque a valve cover.  Unlike a conventional V8 valve cover, the Nailhead only has 2 bolts securing the cover to the engine.  I would tighten mine slightly more than hand tight but enough so they wouldn't loosen from vibration with no issue.  You may also want to check the outer edges of the covers for rust corrosion.

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                  One other possibility if you don't find any of the causes listed above is that you have a problem with too much pressure in the crankcase.  Too much pressure will force oil past the valve cover gaskets. This  is caused by a clogged breather cap, bad PCV 

valve or stuck piston rings from the car sitting too much over the years without being driven. The easiest way to check for excessive

pressure or blow by is to remove the oil filler cap with the engine running. If vapors are shooting up into the air coming out of the

valve cover hole then that is your problem. The best way to get rings unstuck without disassembling the engine is to pour Marvel Mystery Oil down the throat of the carb with the engine running a little at a time. That's how I cured the stuck rings on my Chevelle

that had sat for ten years without being driven.

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Cork gaskets will seal better because they are softer than the rubber variety and the problem is there is not much clamping force on a Nailhead valve cover along with the possibility the valve cover edge is not perfect. I have used both varieties with success but the cork is more forgiving.

Also, make sure your oil leak is not coming from the head gasket. If the head gaskets are original they will be thin steel and sometimes oil leaks from the port which supplies oil from the block into the heads for valve train oiling. Most of my original Nailheads with miles seep a little oil from this area.

  Tom Mooney

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I tried a couple more times with the ones I had on it and gave up.  I have a couple more cars so I took some off one of the other cars that looked straighter, actually they looked perfect, and put them on.  So far no leaks.  One thing that I noticed was the holes where the bolts go through were bent (divoted inward) compared to the other ones even though they looked fine by themselves.  I was thinking that this might have had something to do with it.  I glued the gaskets to the valve covers just to make sure that they would not scootch out when clamped.  Drove it around for a few minutes tonight and burned off the oil that leaked before and they seem OK.  We will see after the cruise tomorrow.  Wish me luck.

 

Tom, I was beginning to think that it might be something like that, still may be but the oil is dripping down into the spark plug area and the head gaskets are below that.  If it seeps from the head gaskets it would be below the exhaust and just down the side of the block, right?

 

Thanks everyone,

 

Mike

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I would still check your oil drain holes and make sure you dont have oil pooling up in the head.  As mentioned the oil level shouldnt be getting high enough to leak that bad past the gasket in the first place.  When I built my engine I poured a quart of oil all over the tops of the valves and drivetrain and it never over flowed the lip of the head.

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I tried a couple more times with the ones I had on it and gave up.  I have a couple more cars so I took some off one of the other cars that looked straighter, actually they looked perfect, and put them on.  So far no leaks.  One thing that I noticed was the holes where the bolts go through were bent (divoted inward) compared to the other ones even though they looked fine by themselves.  I was thinking that this might have had something to do with it.  I glued the gaskets to the valve covers just to make sure that they would not scootch out when clamped.  Drove it around for a few minutes tonight and burned off the oil that leaked before and they seem OK.  We will see after the cruise tomorrow.  Wish me luck.

 

Tom, I was beginning to think that it might be something like that, still may be but the oil is dripping down into the spark plug area and the head gaskets are below that.  If it seeps from the head gaskets it would be below the exhaust and just down the side of the block, right?

 

Thanks everyone,

 

Mike

Yep, but I wasnt sure if you were experiencing oil leaking down the rear of the head area which might not be easy to inspect.

  Tom

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