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Posted by: McMark Dec 2 2004, 12:29 PM

I was just doing some research on Dow Corning 730 sealant. Looks like it's not supposed to be used on Magnesium because of the acid it produces during curing. We have Magnesium tranny cases, right?

http://www.aircraftspruce.com/catalog/appages/dow730.php for the stuff, BTW. I've never bought from them (yet), but it's the only one I could find online.

Posted by: Sammy Dec 2 2004, 12:53 PM

Dow Corning 730 sealant uses acetic acid as a curing agent. Basically it prevents the curing of the sealant. as soon as the acetic acid evapirates the product cures kid of like a reverse catalyst.
BUT...
so does almost every RTV product on the market.
Is it a problem? No, IMO it is not. It may cause some discoloration around the joint. It may cause some etching at the surface, but not enough to measure. This is taken off the manufaturer's product sheet:

(do not use)
• On or near sensitive metals such as
copper, brass, zinc, carbon steel,
galvanized iron or magnesium; these
metals may be corroded, especially
in confined cure conditions, due to
the acetic acid released during the
cure.

So, you can't even use it on steel? I don't buy it, I've used it and many other RTV products on steel with no problems.
As soon as the acid evaporates the potential problem goes away. RTV does not eat up parts. If you have a polished transmission case you might want to protect it from the fumes with some tape, otherwise don't worry about it.

BTW McMaster Carr www.mcmaster.com sells it, part #74925A65, 3-oz. tube for $67.45
Very good stuff but very expensive.
Good ole rtv will prolly work as well ofr lots less $$$$

Posted by: Eric_Shea Dec 2 2004, 01:00 PM

Hellllllllllllllooooooooooooo. Calling Capt'n Krusty

Posted by: Sammy Dec 2 2004, 01:04 PM

LOL, Eric I was thinking the same thing, brought back memories of threads about RTV on engines and the dangers of SS brake lines

Posted by: Brad Roberts Dec 2 2004, 02:22 PM

Talk to Jerry Woods. He used it on ALL the mag engine cases with no issue in over 30 years.


B

Posted by: trekkor Dec 2 2004, 02:29 PM

i think it's some legal cover...

Just like, "Warning- hot coffee may be hot", on every cup, because some clown dumped piping hot on his crotch and sued somebody because it was hot.

KT

Posted by: SLITS Dec 2 2004, 04:50 PM

i think it's some legal cover...

Just like, "Warning- hot coffee may be hot", on every cup, because some clown dumped piping hot on his crotch and sued somebody because it was hot.

KT

Posted by: Ctrout Dec 2 2004, 08:08 PM

I'm in the USAF and we are anal about safety. We have an MSDS for almost everything. The MSDS for the hand soap that my unit uses actually recommends the use of latex gloves when using the product. Go figure.