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Transmission Question...Bleed back Is Ok to Drive?

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  • Transmission / Overdrive: Transmission Question...Bleed back Is Ok to Drive?

    I posted before in the below link and got some answers. I was hoping it was the tail seal allowing trans fluid out, but I was told to check the trans hot and running and mark it off full, then let it sit for a day and check it cold, not running. I see the fluid is then very high. I believe my torque converter is allowing bleed back overnight, as the fluid level is substantially higher in the morning checked cold not running, it is to the top of the stick. I drive this car no more than 1,000 miles per year at most, but do like to drive to ALL shows. I'd like to drive from NJ to Vermont in August. I don't want to get involved pulling the trans to fix something that is not affecting the way the car drives. So here's the question: Is this a problem driving the car, in other words should I assume the transmission is leaking the entire time I'm driving or is this condition only happening when parked overnight. I don't know how the torque converter anti bleed back works, I want to drive it, don't want to fix it and don't want to burn up the transmission!

  • #2
    It boils down to how bad the 'leak' is. If compared to modern vehicles, even a few drops overnight may seem problematic. Truth is, most Studebaker transmissions will leak a few drops overnight; most common leaks are from the rear seal where the driveshaft goes in (easiest to change), front seal (must remove transmission to replace), and the pan gasket (a messy, PITA to change). Your question about torque converter leak down is relevant to other leaks because as it leaks down, the ATF level in the pan increases proportionately; upon initial startup, the transmission may leak slightly more from any of the above locations, bt only for the first few seconds as the ATF is quickly pumped back into the TC. TC leak down, overnight is normal for Studebaker transmissions and, in and of itself, not a cause for concern. If you only drive your car 1000 miles or so per year, even if the transmission is leaking from all the above locations, as long as it is not leaking so badly as to cause any of the following: Blowing back onto the hot exhaust and smoking excessively (unlikely unless driving at higher speeds for long distances, i.e. 20 miles or more on very hot days). Also, if it is leaking so bad it is misting and showing up on your back bumper and onto the windshield of vehicles following closely behind you (not necessarily a bad thing, LOL). Other than those two potential problems, as long as you keep an eye on ATF level; check it weekly and before planned trips, your car will be just fine. Just wipe the drip clean once in awhile so you can monitor leak locations/sources, and note any new or worsened leaks.

    Based on what you wrote here, and in the other thread, I see no worries. Drive your Studebaker and enjoy it.


    • #3
      It appears that in the noted linked String from 2020, that we resolved it to needing a Tail Seal, not a Big Deal especially if THIS Flight-O-Matic is a 1958 to 1966 which we never found out.

      The Good news is; they have a "Slide-In" Driveshaft Yoke, so do not require pulling a "U-Joint Flange", BUT they are harder on Tail Bushings if the Rebuilder missed it, which would be very Rare for an experienced Transmission Rebuilder.

      Yes the Fluid will get higher overnight, only pay attention to the Correct checking proceedure I told you in your earlier String.
      Second Generation Stude Driver,
      Proud '54 Starliner Owner
      SDC Member Since 1967


      • #4
        It's a Studebaker. They mark their territory....


        • #5
          So here's the story and the reason for this second post: I got a tail seal and went to local trans shop and the owner told me he didn't want to waste my money and had me do a series of "tests" before he would consider a tail seal. I had to properly fill it, run it everyday and check it hot and cold, running and not running and of course monitor the drip pan. The results are that the car leaks very little overnight (when driven everyday)but the dip stick is twice as full cold not running in the morning. After running it fills to the correct level. The shop told me the bleed back, evidenced by the high level cold on the stick, is excessive (is Stude World???) He told me the tail seal replacement probably would be a waste of time. He said I have a problem with bleed back and overtime not driving everyday it overruns the seal. The longer it sits not driving the amount on the drip pan becomes larger.

          I don't want to pull the trans to access the torque converter, so that's why I asked if bleed back happens while driving or just when sitting. I can live with filling it before a trip and keeping the drip pan. Any thoughts are appreciated. I never checked it before cold not was a shock to see the fluid up twice as high as from 0 to F, it was twice the height over F.

          Any chance the bleed back valve will "fix itself" by driving more?


          • #6
            The bleed back is utterly unimportant. As soon as the engine starts the convertor refills and off you go.

            If the leak is at the tailshaft and bothers you you could let the unit run a half quart low which will probably alleviate the problem when parked. Better yet, have a new tailshaft bushing and seal installed and have no further worries. It is a trivial job for a good transmission shop provided they are motivated to do it. They are probably scared it will be hard to get the parts. You know where to get them.


            • #7
              I'll try one more time: the man you refer to in post #5 above is either an idiot, con artist, or both. Please refer back to post #2 above. If the rear seal bothers you that much, buy a Shop Manual and change it yourself. It takes less than an hour, if you lived nearby, I'd do ti for you, no charge.