Tm300 servo leak ?

Discussion in 'The "Juice Box"' started by Doug garman, Aug 20, 2018.

  1. Doug garman

    Doug garman Member

    hey gang , I had lots of questions , and the v8 group has answered , thanks , having fun with my 68 custom rag top.
    So here is my question, 68 buick custom, 350 eng, I believe it has a tm300 2 spd, so I’m resealing multiple leaks , and the trans has several, the biggest one was the servo cover, i pulled the cover and replaced the oring, thinking that would be the fix , well it still leaks , do I have a bad cover or a cracked trans, what is common , some trans techs said to put a small amount of sealer around it and reinstall, on a trans I thought oil was no no , let me know what you guys think , thanks
  2. TexasT

    TexasT Texas, where are you from

    I would pull it apart again with another new seal and clean up the place the seal rides on. Lube the seal up so it doesn't get pinched or cut when you put it back together.
  3. Doug garman

    Doug garman Member

    Yep I was heading that way, now 3 different people said after install, silicone around the cover would be they way to go also for added sealer .
    Not looking for any short cuts but is ‘this common for power glides ?
  4. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    What you have is an ST300. Not the same as a Powerglide. It's a 2 speed, but not the same as a PG. Could the cover be warped or bent?

    From above link,

    "Due to its two-speed with torque converter design, the Super Turbine 300 is often confused with Chevrolet's Powerglide — which was also a two-speed torque converter transmission, but the ST 300 was of a completely different design and shared almost no parts with the Chevy unit, which had been around since 1950. The low band was the same as the 1955 up PG along with the same style clutch plates."

    Is it possible you have the wrong seal?
    Last edited: Aug 22, 2018

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