High Temp Silicone Sealant?

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I'm about to replace the valve cover gasket on my Miata and the directions call for a "high temp silicone sealant". Just what product should I be using that I can find at Autozone, Napa, etc.? And just how high temp is "high temp"? I have a tube of Permatex clear RTV silicone that is good for upto 400F. Should I use that? TIA
 
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 Originally Posted By: chuckerants
I'm about to replace the valve cover gasket on my Miata and the directions call for a "high temp silicone sealant". Just what product should I be using that I can find at Autozone, Napa, etc.? And just how high temp is "high temp"? I have a tube of Permatex clear RTV silicone that is good for upto 400F. Should I use that? TIA
I have used that before without issue. If you have it use it! ;\)
 
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Check that permatex clear for "sensor safe"... They mostly are if they're for automotive use but you can't be too careful. The wrong stuff can outgas and wreck your o2 sensors, in theory at least.
 

chuckerants

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It looks like there are two types of silicone RTV: sealant and gasket maker. I'd feel more comfortable knowing I'm using the "correct" stuff so I'll stop by a store and price a tube of Permatex Gasket Maker Black. BTW, due to the supercharger, my engine bay does get quite hot, especially during the summer months (but hopefully not 400F hot). Thanks all. I hope to get to the valve cover this weekend and report back.
 
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The CORRECT stuff is a high temp silicone. Many different ones fit the bill and one isn't really better than the other. I've used the Black RTV a million times on gaskets that get much hotter then your valve cover will. You're worrying too much about something too simple.
 
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Chuckerants, A valve cover is enough headache to want to do it right the first time and not have leaks. Go to the permatex site, then give them a call to for their advice. I have had good luck with their "Ultra" products. When I talked to one of their techs. regarding an unusual non-automotive application, he reminded me that the Ultra products were sensor safe, non-corrosive, and had much better adhesion and oil resistance than the standard first generation RTV's. Made me feel good, but they probably all work. http://www.permatex.com/products/Automotive/automotive_gasketing/gasket_makers.htm
 
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doitmyself is right. I've been using the Ultras since they came out and they're great. Ultra Blue is probably fine for what you're doing.
 

chuckerants

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Yeah, I know I'm worrying about a relatively minor thing, but as doityourself said, I just want to do it ONCE. This is what I got today. http://www.permatex.com/products/Automot...asket_Maker.htm
 Originally Posted By: doitmyself
Chuckerants, A valve cover is enough headache to want to do it right the first time and not have leaks. Go to the permatex site, then give them a call to for their advice. I have had good luck with their "Ultra" products. When I talked to one of their techs. regarding an unusual non-automotive application, he reminded me that the Ultra products were sensor safe, non-corrosive, and had much better adhesion and oil resistance than the standard first generation RTV's. Made me feel good, but they probably all work. http://www.permatex.com/products/Automotive/automotive_gasketing/gasket_makers.htm
 
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Nicely done. As said above there are better grades. The permatex brand stuff at walmart is NOT AS GOOD AS the stuff in parts stores... the ultra series. If you look close the colors are the same but part #s different. The cheap stuff goes on like toothpaste, it's slimy where you want sticky (but it sticks to your fingers well). The good stuff "behaves" much better.
 
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Clear is for aquariums. Use any automotive type for a simple valve cover gasket. CLEAN is the key, and proper cure time also. I believe red has the highest temp rating, at 750 intermittent. But use the Ultra, for O2 sensor safety. Why not spend a few dollars more for the best ? You will have plenty extra for other repairs and gluings.
 

chuckerants

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Thnaks everyone for your help. The Permatex Black Ultra I used seems to be doing the trick. I drove the car after letting it cure overnight - about 10 miles - and no leaks visible. The R & R was a breeze compared to the time it took me to remove all the gunk from the gasket groove on the valve cover. It doesn't look like it was ever cleaned - just a new gasket installed over it.
 
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You just need to use a few dabs of silicone to hold the gasket in the valve cover "groove". You really don't "have" to use silicone...
 
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I know it's too late, but I always liked the Permatex Copper. High temp and overkill for a valve cover, but works well. You will be fine with what you did too, of course.
 
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Many factory valve covers use and recommend a little RTV at the ends, or for corner sealing. Very few factory gaskets never ever leak, so I prefer a little RTV on the whole area. Clean clean, and time.
 
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