1956 Hydramatic: massive oil leak

[Roger Zimmermann]

It took some time to go further with that issue. This afternoon, I went under the car with running engine. To make things clearer, the closing plate at the flywheel housing was removed. At idle, there was some drip, but nothing alarming. It was a different matter when the transmission had to work: with the lever in "D" and some acceleration, there was a flow of oil coming from the back, behind the fluid coupling. The front is staying dry.
The transmission will be dropped and I will get it soon.
Art, you are probably right: the guy who was with me told me that some seals have a steel band embedded into the lip. I will search the old seal in my garbage to confirm this theory. Anyway, the diameter is corresponding to the lip of the seal. It not really a spring steel band as I could untwist it.
As the car drove without issue for some years and suddenly a large leak appeared, something internal at the transmission was happening. What? I will have to discover it.

[Quentin Hall]

I had a crack in my 57 torus cover that the eye could not see. Right on the edge of the Centre weld. Took two goes to fix it, had to tig it up.

[Caddy Wizard]

It took some time to go further with that issue. This afternoon, I went under the car with running engine. To make things clearer, the closing plate at the flywheel housing was removed. At idle, there was some drip, but nothing alarming. It was a different matter when the transmission had to work: with the lever in "D" and some acceleration, there was a flow of oil coming from the back, behind the fluid coupling. The front is staying dry.
The transmission will be dropped and I will get it soon.
Art, you are probably right: the guy who was with me told me that some seals have a steel band embedded into the lip. I will search the old seal in my garbage to confirm this theory. Anyway, the diameter is corresponding to the lip of the seal. It not really a spring steel band as I could untwist it.
As the car drove without issue for some years and suddenly a large leak appeared, something internal at the transmission was happening. What? I will have to discover it.

If the leak is coming from behind the fluid coupling, it seems almost certain to be a failed front seal.

[Roger Zimmermann]

I had a crack in my 57 torus cover that the eye could not see. Right on the edge of the Centre weld. Took two goes to fix it, had to tig it up.

This is a possibility. I did not have a good look at the hard parts when I replaced the seal.

[Roger Zimmermann]

If the leak is coming from behind the fluid coupling, it seems almost certain to be a failed front seal.

It was my logical thinking when I got the transmission to correct this leak. However, the front seal was not bad looking; the one I installed could certainly not leak after the engine was started and used for maybe 5 minutes. However, all is possible. The answer when I will open the beast!

[Roger Zimmermann]

The transmission is back to my shop. To my dismay, I saw nothing suspect, except one thing: the black lip from the flywheel oil seal is very soft compared to the usual seals I have with the red lip. Could that seal be the culprit?
I assembled the torus cover assembly with the flywheel but me method to put some air into the assembly is not quite ideal. I should have the tool J-7073 but this tool is not suited for the 1956/57 as the hub is smaller than the 1958/64 transmissions. However taking in account how much oil came out during the test with running motor, such a large leak should be obvious even with my primitive method: some masking paper to close both small holes, a pice of rubber over the hub, pushed down with a strong ring and a hole for the air in the middle...
I don't see any crack at the flywheel housing...

[Roger Zimmermann]

That damn transmission was overhauled and installed back into the car. The transmission is working very well, very soft passage 2-3. There is just an inconvenient: it was leaking.
So, this week, the transmission came back. I can replace again the seal, as I saw nothing unusual, il will be a waste of time and seal. There must be something else...
I contacted Steve Peluso; he gave me the advise to magnaflux the bowl. The inconvenient: I have to go in Germany for that...
Quentin Hall already wrote that the bowl could have a leak.
The 1959 shop manual is showing a tool to check the assembly, but, as the neck from 1956/57 is smaller, the tool could be not suitable. And how to find it is another issue! As I could not wait, I decided to make a tool. A bit different, but the same purpose.
This afternoon, I could put the bowl assembled with the flywheel under pressure. It's leaking at the neck! The other side has a very nice weld, I don't want to play with welding, so I bought locally a 1958 transmission. I will transfer the whole front to the '56 transmission, like I had on my '56 de Ville.
A long story is coming to a good end!

[Carcadillac]

I have a 1957 with Jetway dual pump transmission, when its filled and running no leaks, after park it, over night quarts leak out, seems to have a few leaks, but did put a snake cam behind the torque converter/flywheel housing and majority is leaking from behind converter.  Taking it out soon to have it checked out.

[Roger Zimmermann]

The filler tube can be a source for leak if the tube is not perfectly round. During the drive, there is no leak but, when the engine is not running, the oil level into the transmission will rise, up to the filler tube.

[Chopper1942]

One of the problems of not having the correct seal drivers for seals that have a garter spring,a spring around the seal's lip to apply pressure to the seal's lip, is on installation the garter spring comes out of its place.  If this happens, you will have a massive leak. Every front pump seal I have installed has had a garter spring. In the past I had one come off the seal eventhough I used the seal drive the OE FSM called for. After that fiasco, I always verified that the garter spring was still in place after I installed the seal with the correct seal driver.

[Roger Zimmermann]

It seems that I never closed this topic. Finally, for some reason, I did not use the '58 fluid coupling, but let weld the neck from the '56 torus cover. It was an interesting process: the welder, a young guy from Ukraine, welded the neck with a system I was not aware: he used a rod and a very thin heat source, minimizing the generated heat. No weld projections on the hub, just a very nice weld. And it was tight as I could see with my testing tool!
The transmission went back into the car and is no more leaking.
Early this year, I overhauled a very ill '56 transmission: the torus cover was full or silver soldering; that transmission was certainly badly leaking maybe 30 or 40 years ago!

[TJ Hopland]

So that area was an original factory weld on one side that must have cracked over time?  And you had someone weld it on the other side?

And when it was in the car it appeared to be the front seal of the trans?


Do you think this leak caused that coupling to drain out faster than it usually would raising the level in the pan/case faster than it usually would causing more leaks?

[Roger Zimmermann]

Yes, the weld on one side was from the factory. And yes, I had somebody who welded on the other side.
Prior to the repair, as I had no clue about the leak, we let run the engine without the steel plate behind the starter motor just to see what was happening. At idle, almost nothing but with the lever in D and some more RPMs, there was a spout of oil coming from behind the fluid coupling. It could not come from the seal at the flywheel housing because there is almost no hydraulic pressure from the transmission's case.
I don't think that the drain from the coupling was much faster with that leak because when no pressure was build up, the leak was minime.

[TJ Hopland]

Ok that all makes sense.  The leak being worse under load I either missed, forgot, or it wasn't mentioned earlier in the thread.  The one I am sort of dealing with now mostly leaks when its sitting for more than a couple days so it sounds like its not nothing to do with this possible neck issue.

Does this thing 'hook up' like a typical torque converter?  But doesn't have the fixed spline for the stator?  So its the input to the trans shaft and a way to drive the pump and direct mode?  I'm just trying to imagine what the stresses would be on that neck.   

[Roger Zimmermann]

No torque convertor here, but a fluid coupling. The neck is just a guide, not attached to whatever internal element. However, next to the torus assembly, there is also a planet gear inside that element. So there are some efforts at the torus cover. Why did the weld fail? I don't know. Usually they are failing when rather "fresh", but this one failed after 67 years.

[TJ Hopland]

These have a 'direct' mode or gear(s) where that coupling isn't in play don't they?  So in some gears this coupling is acting like a clutch and doing some slipping but other gear(s) its bypassed so a direct drive with no slipping at all so its actually fairly efficient.  So the outer part of the hub that engages into the transmission isn't just driving the pump, in some modes its THE drive isn't it?  I'm thinning this is what that neck is probably? So at times its got all the torsional force on it? Vs a torque converter where the force is on that internal shaft.  With these its either on the outer hub neck thing for direct mode or on the internal shaft when its using the coupling indirect mode so to speak

[Roger Zimmermann]

Sorry, but I'm unable to answer thise multiple questions because I don't understand them! Maybe the attached page from the shop manual will give you some answers.