Willam M
   I have a Generac 8kw generator, 410cc engine. It uses valve cover gasket # 0c3150A. The problem I have is that after about six months, the gasket cracks and starts leaking.
   I was wondering if I can use Permatex red high temp rtv gasket maker, in place of using the oem gasket? I am getting tired of having to replace the gasket every six months.
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BrianMartin
I don't see a problem with that. However I'm guessing you just bought a couple of gaskets from a bad batch or old stock? Theres no reason why a new gasket should only last 6 months..
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Willam M
   The gaskets that I use, seem to be made from graphite, not silicone or paper. This graphite material seems to get brittle with age. Does Generac make this gasket in another type of material?
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Birken Vogt
I can't recall one splitting.  I don't like silicone because when removed, chunks have a tendency to get into the oil system if they go down the engine.  If you have trouble with the factory gasket you can get various gasket materials at a parts store and make your own with scissors.
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Sony224422
no way claiming to be an expert, but perhaps your oil breather needs replacing? Possible blow by putting too much pressure on the the gaskets blowing them out
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78buckshot
The valve cover gasket on the 410 engine is made of cork, at least all of them that I service. They do tend to squish and get brittle with age - same as me. The other engine models use a fiber composite gasket that holds up very well. I wonder if your engine is running too hot causing premature gasket failure. I use a little silicone sealer when needed.
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Willam M
The gasket is definitely not made from cork. I WISH IT was.
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Willam M
I wonder if the valve cover bolts are being over tightened, and damaging the gasket. Is there torque specs for the valve cover bolts?
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ORACLESA
Try coating both sides of it with RTV gasket sealer..
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78buckshot
William M, I suggest you call Ziller and ask them to pull the part number, see what the gasket is made of, maybe they have an old and new part number or an old and new gasket to make a comparison. The 410 valve cover is stamped sheet metal and can be deformed slightly from the gasket crushing under the bolts. Of the different engine models the 410 is the one that will leak from the valve cover. The twins have cast aluminum covers and it's rare to have a leak in that area unless the #2 head has a broken mounting ear.
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Willam M
I think you are right. That is where the oil leaks from the most. My valve cover is stamped steel. I wish it was cast aluminium. Thank you!
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Dick from Canada
Mine leaked as well . Went to the auto shop and made my own. As noted by others the cover is stamped. Be sure that the surface is flat, dry and clean. The original was cork,  the one I made is a cork composit used on older car valve cover gaskets, snug but do not over tighten. Replacements from Generac are quite pricey , about $20 comes to mind.
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Willam M
Problem solved! I put on a new valve cover and gasket. The valve cover was no flat along the gasket area. I had no choice but to replace the valve cover. I could tell the cover was over tightend. The bolt areas were crushed in enough, to cause the leak. I am now working on my generator myself.
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