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Re: [GMCnet] porous aluminum tranny pan [message #324317 is a reply to message #324316] Sun, 24 September 2017 18:35 Go to previous messageGo to previous message
Matt Colie is currently offline  Matt Colie   United States
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma:
Senior Member
KB wrote on Sun, 24 September 2017 19:08
Thanks Jim. I was concerned about the glyptal being able to handle the heat of our application,
so your observation is helpful. I recall Manny saying something about seeing 300F temps in there
at one point, though I can't remember where in the system. That made me concerned the glyptal might not hold up to a
heavy vehicle going up and down big hills with a towd... I think there are alternative products that can
handle the heat and the ATF, but I haven't found a definitive enough version yet. "Silver Seal Fluid Weld"
can supposedly do the job, but it appears to be a thick paste, is just as expensive as glyptal, but
can be bought in smaller quantities.

It appears virtually all modern aluminum cast automotive parts are pre-sealed by various industrial processes,
but those don't typically lend themselves to DIY work. I've also read that in the past, GM, etc, used epoxy paste
or RTF for leaky castings. A paint would be a lot easier. I'll be very interested to hear how Ken's experiment turns out.

thanks,
Karen
1975 26'


Karen,

The processes used to seal porous castings is costly and time consuming (the same thing as costly to manufacturing). Unfortunately, porous aluminum or magnesium castings are relatively easy to make, but they are not at all desirable. So, most of our casting suppliers (4 total, but one has gone under - that is the one I worked for a division of) set up testing rigs that use high pressure air and a devices to determine leak rate. If even a small portion of the population does not pass, they all get coated. While this is happening, manufacturing is screaming about everything and the clients (me this last time) are just sitting there and pointing to the contract that says "finished castings shall not leak fluids at a detectable level".

I am personally fond of water glass (sodium silicate) as a sealant because I have never seen in fail once the impregnation process is complete. It has no temperature or solubility issues that I know of.

Matt


Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
 
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