304 valve cover leak RTV or gasket or both?

304 valve cover leak RTV or gasket or both?

suburban99

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Mission City, British Columbia, Canada
Vehicle(s)
1980 CJ7 304 V8
2011 Silverado 4x4
2004.5 Dodge Cummins Diesel
1997 Porsche Boxster
Hey all got chrome valve covers on my 304 and they leak quite a bit. Mostly at the rear. Now that I replaced the rear main and pan gasket, you can see where the oil has run down the block. I have a considerably smaller oil dot every time I park...it likes to mark it territory I guess.
Should I use RTV, new gasket or both?
 
With the rubber ones no RTV but I use it on the cork ones and don't tighten real tight it will split the cork. I like the rubber ones best if you can find them.
 
Do both. Spend a little extra time and get your heads and valve covers cleaned up really well. I would spend the extra money and get a good set of gaskets, Fel-Pro, and buy a tube of permatex "the right stuff". Follow the directions on the permatex and I'd bet money that your valve covers won't leak again.


NAPA AUTO PARTS)


Permatex-25223-rw-53233-63622.jpg
 
If you do decide to use a sealer, Permatex "The Right Stuff" has worked better than anything I've tried. Yes that is the name of it "The Right Stuff", a little pricey but I don't like rework projects. Great advice elwood!
 
I'm kinda doing the same thing on my 304. But I'm just taking my stock covers off to clean/paint. My question is do you guys recommend torque the bolts back to spec or just tighten to snug (slightly compress rubber seal) and then 1/4 turn. I have new rubber seals and I've been recommended to put some RTV on the cover, apply rubber seal to cover and then apply some RTV to seal before assy to head. Basically, put a small amount of RTV on both sides of the seal.
 
With the rubber ones no RTV but I use it on the cork ones and don't tighten real tight it will split the cork. I like the rubber ones best if you can find them.

:agree:
 
The best results that I have had is with getting contact surfaces super clean and sealant on all surfaces. I doesn't matter on how you do it so long as it doesn't leak.
 
Here's what I do with AMC V8 valve covers. It's worked on the 5 engines I've had over the years. Not one has ever leaked a drop after I was done.

Every engine I worked on, the previous owner had cranked down the bolts and bent the flange on the cover, causing oil leaks.

1. Take the valve covers off and flatten out the flange with a hammer on a flat surface. Check all the holes. They should be completely flat all the way around. Lay the top side of the flange against a flat surface and use a hammer to flatten out the hole from the inside. It doesn't take a whole lot. The metal is thin and easy to work.

2. Clean the surfaces well. Make sure all oil is off both mating surfaces. Hose out the inside of the valve cover with some brake cleaner and wipe down the contact surface on the head.

3. Get quality valve cover gaskets. I use Fel-Pro but there are other good brands out there. Get new ones, even if the others were previously new. If they were leaking, especially if the covers were over tightened, there's a good chance they were crushed or deformed and they will never seal right.

4. Use something to attach the rubber gasket to the valve cover. I use a very thin coat of RTV inside of the lip on the valve cover. Others use gasket adhesive. Either way, you want the rubber gasket to fit inside the lip on the valve cover and not move around. If it's just hanging there you run the risk of it not lining up properly when you put the cover on. If it's not in the right place, it won't be in position to seal or, worse yet, get sliced apart when you torque down the bolts.

5. Tighten the bolts properly. There's no need to go in any particular order but you must not over tighten them. Let me say that again. Do not over tighten them! The torque spec is measured in INCH-pounds. It's around 50 if I remember right, which is just a hair over 4 ft-lbs. That's very light. The valve cover is not holding in any pressure. It's just snug enough to prevent leaks. If you don't have a torque wrench, use a nut driver (not a socket wrench) and spin the bolt down until it makes contact. Turn it a little further but not too much. A full turn may even be too much. Just get it snug. If you crank the bolts down, they WILL deform the cover, crush the gasket at the hole and you WILL get oil leaks.

Do that and you'll enjoy years of leak free driving. At least you'll be free from the leaks on the valve cover.
 
Mine have stopped leaking now. New gaskets and RTV on both sides with clean surfaces. The biggest issue was the PO had installed t-handle valve cover bolts and the threaded portion was bottoming out before contacting the washers on the valve covers. Replaced the fancy t-handles with allen head bolts and washers and all is well. No over tightening of course.
 
Mine have stopped leaking now. New gaskets and RTV on both sides with clean surfaces. The biggest issue was the PO had installed t-handle valve cover bolts and the threaded portion was bottoming out before contacting the washers on the valve covers. Replaced the fancy t-handles with allen head bolts and washers and all is well. No over tightening of course.

That would do it.

On one of my Grand Wagoneers, I had to replace the wood screw the PO had run in one of the holes. :rolleyes:
 

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