1978 931 Transmission Seals / Removal

There aren't any seals other than o-rings on the shaft of the torque converter and one on the carrier. Everything is self contained with the one sump and transmission pump handling all requirements. If all or most of the oil winds up in the case and no go check for leakage of the two seals on the tube that connects to the transmission controls on top of the transmission. These are somewhat notorious for leaking.
You did check the suction screen?

Old Magnet,

Thank you for the reply and suggestions. I have checked the tube (see pic) and both of the O-rings fit very snug and appear to be damage free. This is the tube you are referring to, correct? I will replace them when the transmission is reassembled. When you mention checking the suction screen, what are you referring to? The filter? Thank you.

Newt

Edit: After thinking about your suction screen comment over lunch, were you thinking about a screen over the oil pickup tube? The pickup tube in this transmission didn't have a screen on it.

I was referring to the screen under the cover plate on the bottom of the transmission case.

Well cancel that, early units have the horizontal strainer in the bottom of the case. I see it on your work bench. It uses two seals on a connecting tube that should also be checked.
Have you checked clearances in the transmission pump.
Would have been a lot better if there had been some trouble shooting of the transmission controls before dismantling.

Hi Team,
as OM noted, the Trans Filter on these units is actually a very fine mesh within the Trans Pump suction screen. Over time the mesh clogs up, especially if the screen has been cleaned in a dirty Kero bath--fine lint and the black sludge that I see in your case are some of the usual culprits--from experience it is not usually possible to clean the screen--yes--I have tried after cleaning with steam, Kero, etc. and using air to try and back flow the crud out, all to no avail for a customer at The Dealer due to the cost of them and could not improve the flow rate. When clogged, the trans pump cannot pull oil thru the screen and so the Trans does not function as designed--lack of oil supply.

From memory the O Ring in the pump elbow is a black one and they harden--I can see that the yellow O Ring visible on the pump to valve tube is flat and so is suspect--has lost its round section--I note that you intend to renew.

The oil you found in the flywheel housing would be leakage from the Trans/T/converter after the engine was last stopped.

The oil in the flywheel housing is pumped back to the trans case via the windage action of the flywheel/ring gear and deposited into a trough about half way up the side of the F/W housing and runs back to the trans case thru the cast passages you can see in both the F/W housing and trans. housing--cannot recall if there is a screen at the trough in the F/W housing too long ago and I have no literature for these later units.

Trying to recall if I came across the drive spline front attachment in the T/C being loose or the T/C housing cracked on these that may account for the amount of oil in the flywheel housing.

Some things to get you started--keep us in the loop so we may be able to help further with anything else you may find amiss along the way.
Cheers,
Eddie B.

[quote="edb"]
The oil in the flywheel housing is pumped back to the trans case via the windage action of the flywheel/ring gear and deposited into a trough about half way up the side of the F/W housing and runs back to the trans case thru the cast passages you can see in both the F/W housing and trans. housing--cannot recall if there is a screen at the trough in the F/W housing too long ago and I have no literature for these later units.[/quote]

Thank you both for your comments and suggestions, most certainly will buy a new filter/screen along with every seal and gasket in the transmission. This deep into it, all wearable items are being replaced.

Eddie has solved a question I had about that passage that runs through the bell housing into the transmission, thank you for the explanation. That makes perfect sense now.:tea:

I will give updates after the parts arrive and start assembling the transmission, along with any questions that most assuredly will come up.

I told my son yesterday that I feel as if I am in over my head in the deep end of the pool. My friend, Bob, is the brains of the operation here, I am the go-fer. Thank you for your help and suggestions.

Newt

Hi Team,
as OM noted, the Trans Filter on these units is actually a very fine mesh within the Trans Pump suction screen. Over time the mesh clogs up, especially if the screen has been cleaned in a dirty Kero bath--fine lint and the black sludge that I see in your case are some of the usual culprits--from experience it is not usually possible to clean the screen--yes--I have tried after cleaning with steam, Kero, etc. and using air to try and back flow the crud out, all to no avail for a customer at The Dealer due to the cost of them and could not improve the flow rate. When clogged, the trans pump cannot pull oil thru the screen and so the Trans does not function as designed--lack of oil supply.

From memory the O Ring in the pump elbow is a black one and they harden--I can see that the yellow O Ring visible on the pump to valve tube is flat and so is suspect--has lost its round section--I note that you intend to renew.

The oil you found in the flywheel housing would be leakage from the Trans/T/converter after the engine was last stopped.

The oil in the flywheel housing is pumped back to the trans case via the windage action of the flywheel/ring gear and deposited into a trough about half way up the side of the F/W housing and runs back to the trans case thru the cast passages you can see in both the F/W housing and trans. housing--cannot recall if there is a screen at the trough in the F/W housing too long ago and I have no literature for these later units.

Trying to recall if I came across the drive spline front attachment in the T/C being loose or the T/C housing cracked on these that may account for the amount of oil in the flywheel housing.

Some things to get you started--keep us in the loop so we may be able to help further with anything else you may find amiss along the way.
Cheers,
Eddie B.

[quote="edb"]
Trying to recall if I came across the drive spline front attachment in the T/C being loose or the T/C housing cracked on these that may account for the amount of oil in the flywheel housing.[/quote]

The torque converter housing is not cracked, we can rule that one out. Need to buy a small 12 point socket to take the torque converter apart which I am doing this afternoon. Will report back what I find. It appears that the pump is working well based on the amount of oil that was taken out of the transmission and put into the bell housing in a short amount of time. The obvious place to look would be the torque converter. Thanks, as always.

That's why testing before tear down is required. There are test ports for converter pressure and the transmission pump. Pump needs to make about 300 psi in operation.

Yes, my friend and I were just talking about that - we probably have cost ourselves a lot of work and $ for not testing beforehand. Live and learn. Those lessons you buy are usually the ones that stick with you. 😮hwell: Wish I would have found this site before we started the tear down and asked a few questions then......

Thank you as always.