1956 transmission/torque converter leak

[George Clayton]

The transmission does not leak while engine is running. A short time after driving there is a sizeable pool of fluid underneath the transmission. Despite the fluid leaked, the transmission dipstick still registers full. Most recently the tranny did not shift into reverse until I revved the engine. Finally, it slammed into reverse. Have no idea what is going on. Help needed.

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[cokefirst]

Transmission leaks can be tricky. Does this leak puddle under the torque converter? If so, it may be the seal on the torque converter itself. look under the car after it has sat for a while and see if you are getting a drip from the torque converter area. If it is not leaking there, you can put it up on a rack and check for leaks.

 

[74 Harley]

The slamming into reverse sounds like the front pump is cavitating, probably getting near the time for a rebuild if your fluid is not low.

 

[paul5456]

Are you checking the fluid level with the engine running and warmed up? That is how it should be done.

 

[willcarterdc]

Are you checking the fluid level with the engine running and warmed up? That is how it should be done.

I second this question/suggestion. I only recently learned myself that the engine needs to be warmed up *and* running when checking the transmission fluid level. (I knew it had to be warmed up, but didn’t know until recently that it had to be running.) In my case, the difference was substantial: when checking with the engine warmed up but off, the transmission dipstick always showed near Full. When checking with the engine warmed up and running, it showed significantly below Low.

So: are you checking the fluid level with the engine warmed up and running?

 

[George Clayton]

Checking when warm, not running. Will check when running. Thanks for replies.
Not sure what "front Punp"
Is??

 

[74 Harley]

The front pump sits right behind the torque converter in your transmission. It's not serviceable with the transmission in the car.

 

[swatson999]

I don't have it handy in either paper or electronic form right now, BUT...

Doesn't the Shop Manual *specifically* give instructions on how to check this (engine warmed-up, shift through R-N-D, etc.)?

 

[willcarterdc]

The owner’s manual definitely doesn’t; the Shop Manual might (I have both but don’t have the latter at hand at the moment). Speaking for myself, though: so what if it does? Those of us who didn’t know the procedure but could have known had we found it in the shop manual simply made a mistake, which is part of the process of learning. (For that matter: I might very well have seen it in the shop manual at some point, but didn’t have it at top of mind when occasion arose to check the transmission fluid)

 

[swatson999]

Because by not looking up the right procedure, you may have convinced yourself that the fluid level was fine when it wasn't, and caused a lot of (expensive) damage?

 

[willcarterdc]

Because by not looking up the right procedure, you may have convinced yourself that the fluid level was fine when it wasn't, and caused a lot of (expensive) damage?

But I didn’t. Because I asked folks (elsewhere, not here) for advice, which they were happy to give constructively. But even if I had cause damage, I don’t see how that would be your problem

Anyway: not my thread, so I’m out; just wanted to point out that gatekeeping comments like “why didn’t you check the manual?” are neither helpful nor encouraging. Everyone has different stages of learning and knowledge, so my preference is to help rather than hector people.

 

[swatson999]

That's fine, and that's your preference, and there's nothing wrong with that. I just find that this happens on a number of forums that I'm on for different things (the Tbird, airplanes, etc.)...people not expending the effort to *read* the instructions that the designer/manufacturer wrote down, which usually explicitly and clearly and *correctly* describes how to accomplish the task. And the book is always available...no waiting for on-line responses. And from what I've seen, about 1/4 of the time, the responses on-line are flat-out wrong, or answering a different question, or talking about something else entirely.

I may be old-fashioned, but I like to "teach a man to fish" 🙂. Now, if someone has done the research, and read the manuals, and still can't sort it out (or the info isn't there in the first place), then that's what forums are for. 🙂 Been there myself, many times.

 

[doug7740]

The owner’s manual definitely doesn’t; the Shop Manual might (I have both but don’t have the latter at hand at the moment). Speaking for myself, though: so what if it does? Those of us who didn’t know the procedure but could have known had we found it in the shop manual simply made a mistake, which is part of the process of learning. (For that matter: I might very well have seen it in the shop manual at some point, but didn’t have it at top of mind when occasion arose to check the transmission fluid)

The attached procedure is from the Fordomatic car-truck shop manual.

doug7740
1955 Thunderbird Blue

 

[Bill's57]

I have the same issue with my transmission in my 57 the leak on my transmission is around the gear shift lever on the transmission as yours it leaks when it's not running, the problem of it taking a long time to go into reverse, it has progressively gotten worse and taking longer and longer to go into reverse and now it takes its sweet old time to shift from second to third also. But once it shifts OK the first time after it warms up, it is fine until it cools down, then the process starts all over again. The car was restored some time ago, and has seen very few miles during this time, I also am looking for someone with insight on possible causes, wrong type fluid, problem with seals etc. And no it is not a problem of fluid level

 

[doug7740]

Looking at the attached Band/Clutch Application Chart, the only component that is applied in reverse and high gears is the rear clutch. Since it is taking a long time for the transmission to engage in reverse and third gear, that tells me that the piston seal G15 & G16 in the rear clutch is leaking. I would not continue to drive the car, because you will only cause further damage.

doug7740
1955 Thunderbird Blue

 

[George Clayton]

Thank you for your insight. I will examine this closely. Looks more and more like a need for a trans specialist.

 

[Bill's57]

Looks like I'm pulling an engine this winter, thanks for sharing your knowledge