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Gasket Maker Question
I am replacing an O Ring on a Honda engine oil cooler and with Permatex Sensor-Safe High-Temp RTV Silicone Gasket (red). The TDS for the product states 24 hour cure. I assume I need to wait 24 hours, or will it acually seal faster? -- ramseybuckeye ------------------------------------------------------------------------ ramseybuckeye's Profile: http://www.automotiveforums.com/vbul...?userid=464717 View this thread: http://www.automotiveforums.com/vbul...d.php?t=598412 http://www.automotiveforums.com |
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Gasket Maker Question
ramseybuckeye wrote: > I am replacing an O Ring on a Honda engine oil cooler and with Permatex > Sensor-Safe High-Temp RTV Silicone Gasket (red). The TDS for the > product states 24 hour cure. I assume I need to wait 24 hours, or will > it acually seal faster? > > > -- When they say 24 hours for full-cure, that's what they mean. They made the product and silicone is still silicone. The cure rate has been about the same for years. However, I have found some that sets up very quickly and you could assemble in a few minutes and wait for the full cure. But when you block the air, you retard the curing. It is possible to have silicone that almost never cures, just like when it's in the tube. I have doubts as to whether this is a good application for the product anyway. If it had an O-ring, I would always replace it with an O-ring. If this doesn't leak right away on you, it certainly will degrade over time and leak-in my opinion. |
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Gasket Maker Question
On Sat, 29 Jul 2006 06:10:06 -0700, ramseybuckeye
> wrote: > >I am replacing an O Ring on a Honda engine oil cooler and with Permatex >Sensor-Safe High-Temp RTV Silicone Gasket (red). The TDS for the >product states 24 hour cure. I assume I need to wait 24 hours, or will >it acually seal faster? What you are doing is quite dangerous. If a little string of silicone breaks off and blocks an oil metering hole it could be disasterous for the engine. Don www.donsautomotive.com |
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Gasket Maker Question
ramseybuckeye wrote: > > I am replacing an O Ring on a Honda engine oil cooler and with Permatex > Sensor-Safe High-Temp RTV Silicone Gasket (red). The TDS for the > product states 24 hour cure. I assume I need to wait 24 hours, or will > it acually seal faster? Most of the silicone adhesives sold for automotive application are moisture-cure silicones, so moisture in the air is the usual agent for curing and the rate of cure depends on the humidity. This can be accelerated with the direct application of water or steam. The problem is that if you get the outer skin to cure too fast that creates a moisture barrier that prevents the inner part from curing. That's more of a problem if the application is thick or pushed deep into a crack. A thin film of soapy water on the surface is considered by some to be the best method to get a rapid cure and a smooth blended surface (like when you are caulking a bathtub). Others claim a little spit on the tip of your finger is the best method of shaping the surface and getting a rapid cure. -jim ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
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Gasket Maker Question
The others are right about this not being a good way to go.
Your real question is about the RTV. RTV cures when it is exposed to the moisture in the air. The cure time varies with the amount of moisture in the air. The instructions probably says 24 hours for "full" cure. The cure rate is exponential. That is it will reach 1/2 cure in a couple of hours 3/4 cure in about 8 hours and so on until full cure is achieved. In your application, I would roughen it up some with 220 grit and solvent clean the surface. Then apply a thin layer to each side making sure to keep it away from the oil passage. Since it needs moisture from the air to cure, wait 5-10 minutes before assembling. My experience is that RTV doesn't like hot oil under pressure. "Don" > wrote in message ... > On Sat, 29 Jul 2006 06:10:06 -0700, ramseybuckeye > > wrote: > > > > >I am replacing an O Ring on a Honda engine oil cooler and with Permatex > >Sensor-Safe High-Temp RTV Silicone Gasket (red). The TDS for the > >product states 24 hour cure. I assume I need to wait 24 hours, or will > >it acually seal faster? > > What you are doing is quite dangerous. If a little string of silicone > breaks off and blocks an oil metering hole it could be disasterous for > the engine. > > Don > www.donsautomotive.com > |
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Gasket Maker Question
"Scott Buchanan" > wrote in message ... > The others are right about this not being a good way to go. > > Your real question is about the RTV. RTV cures when it is exposed to the > moisture in the air. The cure time varies with the amount of moisture in the > air. The instructions probably says 24 hours for "full" cure. The cure rate > is exponential. That is it will reach 1/2 cure in a couple of hours 3/4 cure > in about 8 hours and so on until full cure is achieved. > > In your application, I would roughen it up some with 220 grit and solvent > clean the surface. Then apply a thin layer to each side making sure to keep > it away from the oil passage. Since it needs moisture from the air to cure, > wait 5-10 minutes before assembling. > > My experience is that RTV doesn't like hot oil under pressure. I don't fully agree with your chemistry, but the facts are that if you dont do it correctly, you can get in trouble. If you do the work properly, and have the appropriate silicone compound, they work well. You ABSOLUTELY MUST let this material 'vulcanize' completely before putting it into service. This may take a number of hours. ( On the blue RTV, I found I got best results when letting it cure 12-24 hours. I got a lot of leaks until I developed patience in the curing process.) Some people on here used to recommend letting it wait a few minutes until it 'skins over', and then assembling it ready to use. NOT SO. It should stand undisturbed, dry, until the curing process is complete. As Don said, if you get an engine full of silicone strands or flakes, you have bought into trouble. |
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Gasket Maker Question
> wrote in message ... > > I don't fully agree with your chemistry, but the facts are that if you dont > do it > correctly, you can get in trouble. I guess I should have gone a little further, if I were going to say anything about curing. Common types are acetoxy/acetic acid/anhydride based, where moisture initiates the cure with release of small amounts of acetic acid. These are the cheaper and more ordinary variants. There are others, better and more expensive, which depend upon other reactions. A catalytic amount of moisture will start this type of crosslinking reaction. Too much water is not a good thing. And that is enough about chemistry. Read the instructions, err on the conservative side. Better still, use the O-ring that was designed for the application. |
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Gasket Maker Question
shiden_kai wrote:
> > For you hobby mechanics, you have the time to let these things > "set up". It's not possible for a flat rate dealer tech to do it this way > unless I had 3 bays (which I don't). > > Ian > I'm a diy-er, and I'll admit to not waiting for the silicone... once the parts are reinstalled, it's time to test-fire it. Not been a problem. of course, I'm not reinstalling an oil pan and immediately driving 500 miles... usually just around the block and then leaving it overnight, so I guess it has a chance to cure. My best/worst silicone jobs are the end seals on a "classic" SBC. Every third time we do it it leaks and I have to redo it. Always in the same spot, back by the oil sending unit. But I'm getting better. (don't ask why the intake is coming off so often... but if you wanna know, I've gone through a couple of engines... and swapped cams and intakes for more power... and the odd blowed up engine...) Ray |
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