Powerglide Leak Repair Suggestions?

[A S.]

64 coupe- power glide transmission- 327/300 hp. Trans fluid leaks while sitting after a few weeks w/o being started or driven. First time , loss was almost a quart. After refill to just under full mark, lost about Half quart. Spilled underneath filler tube, approx. Does not leak while running. Cause?

[Gary C.]

Re: A.t. Schraner (66309)

A.T.

Please post your question in the Technical Discussion Forum.

This is a "how do I use" the TDB forum?

It says up at the top "Not for Technical".

Gary
....

[Joe R.]

Re: Powerglide Leak Repair Suggestions?

This is a known problem with the Powerglide that is annoying but not serious. When the engine is running, transmission fluid is pumped up into the torque converter. The upper portion of the torque converter is well above the transmission oil pan.

When the engine is shut down, a check valve inside the transmission is supposed to keep the fluid in the torque converter from draining back into the transmission oil pan. However, if this check valve has a slow leak and the car sits for a long time, the fluid in the torque converter drains back into the oil pan and the fluid level in the pan rises above the normal level.

This can cause fluid to leak out around the O-ring seal where the dip-stick tube meets the transmission, and also around the seal at the speedometer output. Both of these locations are not designed to be below the oil level in the pan.

One way to prevent the leak is to simply start the car periodically, say, once a week. Simply starting the car will cause the front pump in the Powerglide to re-fill the torque converter.

Replacing the seals on the dip-stick tube and the speedometer output should greatly reduce the leak, but in my experience the speedometer output still drip a little bit.

A complete fix would require removing the pan, dropping the valve body, and cleaning/replacing the leaky check valve.

[James G.]

Re: Powerglide Leak Repair Suggestions?

PUT THE trans in reverse and turn off the engine. As Joe says, a check valve inside the transmission is supposed to keep the fluid in the torque converter from draining back into the transmission oil pan. However, if this check valve has a slow leak and the car sits for a long time, the fluid in the torque converter drains back into the oil pan and the fluid level in the pan rises above the normal level. It will work better in gear with engine turned off.

[Edward J.]