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Drivetrain => Transmissions => Topic started by: Brian on September 17, 2012, 09:06:50 PM

Title: ST300 transmission pan sealing
Post by: Brian on September 17, 2012, 09:06:50 PM
How is everyone sealing the transmission pan to their ST300 auto transmission.  My '66 gets driven very little (once every couple months), and in the 25 years I have owned it, I have never been able to get the pan gasket on the trans to no leak when sitting around.  I have one of the composit rubber gaskets on it and that has worked best (compared to the cork gaskets).  Has anyone ever tried putting the pan on with a thick bead of silicone RTV with no gasket installed?  I know that is how alot of modern engines and transmissions seal their joints now and it works very well. 
Title: Re: ST300 transmission pan sealing
Post by: Dr Frankenbuick on September 18, 2012, 06:29:11 AM
Mine also seems to leak from the band adjustment port as well as the transmission pan!  I want to to fix this all at once when under there, and am very interested in the answer to Brian's question.
Title: Re: ST300 transmission pan sealing
Post by: mdkd on September 18, 2012, 11:42:35 AM
Brian

    Me too.

Milton
Title: Re: ST300 transmission pan sealing
Post by: WkillGS on September 18, 2012, 06:12:46 PM
I generally use a THIN layer of silicon on my gaskets as an adhesive and to fill pinholes. Also makes removal and future clean-ups much easier.

My Special had an annoying leak at the o-ring seal on the (servo cover?)
My final solution was to install a 5 speed. :icon_biggrin:
Title: Re: ST300 transmission pan sealing
Post by: gs spoken here on September 19, 2012, 07:40:47 PM
I had a 68 300 that was a reak leaker, turned out to be the connector for the kick down, I bought a new one from a local trans supplier for $3.00 and it stopped 99% of the leaks, thanks Bill.