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  1. #1
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    Default Trimatic oil leaks

    Hi all

    My trimatic is currently out the car as I am in the process of rebuilding the motor.

    Using this opportunity to attend to some leaks in the trimatic. Its one of those situations where you not sure where its leaking from but it is leaking. Generally it will leak some ATF after I drive, there will be a wet patch on the floor. Have tried in the past to locate the leak but gave up. Looked in the usual places, dipstick tube, torque converter area front seal, sump. Sump is always wet but if it was the sump them it would leak all the time when standing as well. I did replace the sump gasket just to be sure as well.

    What do you guys suggest I do in terms of which gaskets to replace. Thus far I am thinking, new sump gasket and filter, from oil seal, selector shaft seal.

    I was told replace the pump gasket as that can leak when the vehicle is in gear,. I am hesitant to do that as it means going into the box which I am not confident on. How difficult is that job? Any you tube videos you can refer me to.

    Would really appreciate all advice on this.

    Thanks in advance
    kavesh

  2. #2
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    Default

    More than likely it'll be leaking from the selector seal, very common leak on the old trimatics. Oil leaks out of the seal and runs along the pan gasket and gets missed diagnosed as a pan gasket leak then people over tighten the pan bolts and squeeze out the cork gaskets, the pan bolts should never be wrenched tight to a inch of there life. As an old trans specialist years ago I saw this numerous times. 90% of oil leaks on a trimatic was always from the selector seal.

  3. #3
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    Default

    The pump gasket wont leak externally, has to get past the pump o-ring to do that.

    These things have so many places to leak from.
    Selector seal, pan gasket, detent sleeve o-ring, detent solenoid o-ring, modulator gasket or body, speedo o-ring, filler tube o-ring, extension housing seal are all common ones.

    Early Trimatics are known to crack bell housings.

    Extension housing gasket, pressure port plugs, cooler unions, pump o-ring and seal are less likely but possible leak points.

    If it's leaking out of the breather its either overfull or has a cross leak somewhere.

  4. #4
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    Default

    Quote Originally Posted by HQ 368 View Post
    The pump gasket wont leak externally, has to get past the pump o-ring to do that.

    These things have so many places to leak from.
    Selector seal, pan gasket, detent sleeve o-ring, detent solenoid o-ring, modulator gasket or body, speedo o-ring, filler tube o-ring, extension housing seal are all common ones.

    Early Trimatics are known to crack bell housings.

    Extension housing gasket, pressure port plugs, cooler unions, pump o-ring and seal are less likely but possible leak points.

    If it's leaking out of the breather its either overfull or has a cross leak somewhere.
    Well its good to know that its unlikely or can't be the pump gasket. That pleases me as I was not keen to dig in that far.

    Do you suggest replacing all seals that can be accessed externally? That would be many seals. What do you do when the trimatic is on the floor and not requiring a rebuild. Just replace all seals or only the ones that are leaking?

  5. #5
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    If someone asked me to do a re-seal on a Trimatic, I wouldn't even entertain the idea.
    Just no interested in a can of worms.

    If I was you I'd clean it down really carefully as good as you can and monitor it closely, fix the leak when you establish exactly what it is.
    You start trying to fix things that are not leaking, you might end up in a predicament.

    If it is the detent sleeve o-ring you can clean it off with solvent and use an RTV or similar sealant and wipe across the surface with a scraper to neaten it up.
    Don't try and remove the sleeve just in case it goes badly.

  6. #6
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    A friend of mine who passed away many years ago reckoned the Trimatic was mis-named, should have been Traumatic.....

  7. #7
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    With the trimatic on the floor out of the vehicle, I will look at the seals that would need replacing with the box out the car. Right now the only one I can think of is the front oil seal where the torque converter slides into. Having said that I am sure its not leaking here but will replace it anyway while the box is out.

    If I can find an appropriate tool I will also do the selector shaft seal. We do not have stores here where one can just buy the tool. I have the detent kickdown cable removed, so will replace the O ring as well and will use some RTV to make sure it does not leak.

  8. #8
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    Quote Originally Posted by GtoGeoff View Post
    A friend of mine who passed away many years ago reckoned the Trimatic was mis-named, should have been Traumatic.....
    I have heard that before but to be honest I am happy with the trimatic thus far, except for the leaks,

  9. #9
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    I could never understand why GM had the Trimatic and the T350, both designed about the same time. Both were light duty 3 speeds. No wonder GM nearly went belly up....

  10. #10
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    Trimatic was a Euro trans and designed for 4 bangers, light and economical. Fiats, Peugeot's, Opels and Rovers etc.
    The 350 was primarily a V8 trans and was seamlessly smooth but heavy, way too heavy for what it was.

    Trimatic took a bit of work by the Aussies to make it work and live behind a V8.
    The 4 pinion planetary is now desirable overseas which has helped the drying up of good S/H parts over here.

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