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Tranny Leak Finally Fixed!!

Discussion in '365 GT4 2+2/400/412' started by SouthJersey400i, Oct 30, 2019.

  1. SouthJersey400i

    SouthJersey400i Formula 3

    Mar 14, 2007
    1,202
    Romulus, NY (Finger Lakes)
    Full Name:
    Ken Battle
    After 13 years of dealing with a significant leak from the TH400, I finally got it fixed. Here, the only American part on the car was the biggest leaker! I bet a few of you know where this is going but I will tell the whole story and try to be brief. There is no shortage in experts around that know all about the TH400.

    Here is all that I have done:
    - first everyone said be sure to use a composite gasket not paper or rubber - done
    - hammer flat the distorted steel flange holes - done
    - switch to al aluminum pan that does not distort - it took Summit Racing two tries to get me a good one - done
    - bolts are allen heads due to less space for bolt head.
    - supplied SS bolts would not keep torque so replaced with normal steal ones (black) - done
    - Used "Form a Gasket" on both sides of gasket - done

    None of the above fixed the leak! Every time I checked if the front seal was the cause of the leak and it was always dry on front face behind the torque converter.

    A few months ago I brought car to an exhaust shop to get a small crack welded in my exhaust. Guy saw the leak and first gave me the lecture about composite gaskets and he looked again and said 'oh, you have the right gasket'. He then told me the "switch connector" was leaking; he said the o-ring was bad but you had to drop the pan to get the connector out. It is just a piece to connect a wire from outside to inside the tranny. It was easier to buy the connector with o-ring than just the right o-ring, cost $14. So down comes the pan and out comes the connector and the o-ring sure was "flat" and obviously been leaking. Note connector is the single wire one but I bought a two connector one but they fit the same just get both wires on same pole.

    Note: I used Form a Gasket on pan side of gasket and non-hardening Hylomar on the tranny side. Gasket should come down with the pan if I ever need to do so. of course I replaced filter while at it.

    I just verified today that after doing about 2000 miles last week, THERE IS NO LEAK. Its a long overdue success. I hope this saves someone else the trouble.
    Ken
     
    Ak Jim, rubenpadron, raemin and 2 others like this.

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