ATF Pump Leak

[912126]

1990 Subaru Legacy FWD wagon.
I have a heavy leak - 2 quarts per day of driving. No leak when not running. Close examination indicated leak at front, bottom of transmission (under pump slice). Was not dripping down from above.

There are two square (~4mm) headed plugs, with a machined hole between. Leak is plugs, hole, or gasket at that point. As it only leaks when running, seems gasket is unlikely. But gasket is easy to check (only 20 bolts), so I removed pan, hammered out a dent, cleaned and checked flatness.
It got dark, so I haven't refilled.
Question: what is the hole between the plugs for?
Could it leak?
I'm working under the driver's side with about 10" of clearance, so I can't look into the hole.
I removed one plug, the o-ring seems intact, but plug was overtightened.
All comments welcomed.

Thanks

Dale

[Legacy777]

Hi Dale,

Any chance you could take a picture as I'm not sure what exactly you're referring to?

[912126]

Yes.
I have put things back together, replaced fluid, run and watched leak.

I replaced "O" rings on test plugs, and leak is the joint between oil pump and AT, or pan gasket. As it only leaks when running, must be joint.
The pan overlaps the joint, so I can't actually see the atf drip out, but ...
I have some pics, taken from just back of the the driver's front wheel.
(I think I now must upload pics to Photobucket & link.)

Dale

Pictures, I think:

Photo from behind driver's wheel, looking at ATF pump. At the bottom of the pump, just to the left of the ATF pan, are two 7mm-square plugs. My original question was "what is the hole between these plugs?". I was interested because fluid was dripping off these plugs, but neither was leaking.




After raising the car a little, I could see the hole. Still don't know what it is for, but it isn't leaking.





Photo taken from just behind the driver's front wheel. The seam between the Torque Converter Case and the ATF Pump is visible.
The seam between the ATF Pump and Transmission case is hidden by the ATF pan, and grease. ATF is leaking from that joint, I think.
Because I can't see the seam when the ATF pan is in place, I can't see the leak. I did clean and examine the seam, as I did the two square plugs, when the pan was off.
I will clean the balance of the pump, remove the pan, and examine the seam again.

Dale

[Legacy777]

I'm not sure what that hole is in between the bolts.

The leak may be the seal on the torque converter shaft and it's leaking down through the diff and trans cases.

[912126]

I cleaned and rinsed the area in question. Ran engine to ensure the fluid wasn't running from above. Drained, removed pan, and looked closely this time.

There is a 30mm by 0.4mm channel cut across the transmission edge that mates with the fluid pump. Fluid is coming out here.


Sadly reminiscent of the weep hole in the water pump: meant to be an early warning that an interior shaft seal is failing.

I took two poor photos to attempt to show the channel.

First, front of car is at top of photo.



Second, front of car is at right side of Photo.


As I have no desire to replace, or pay to have someone replace, the seal, it looks like time to put her down.
All comments cheerfully welcomed.
Have a pleasant holiday all.

Dale

[Legacy777]

Yeah, I wouldn't want to replace that seal. I don't know if they make and stop leak. You could try that as a bandaid, but usually those stop leak products end up gumming things up.

[912126]

Hi again,

I found this wonderful picture of transmission and pump, apart. The circled areas indicate where my leak is. Fluid flows through the holes from pump to transmission and back. The leak is happening at the point closest to the outside. Oil travels across 10mm of gasket to get out. The path downstream may be constricted, forcing some fluid to break out.
If that's the case, Leak Stop probably won't work until path is cleared.

Anybody have any idea what the gasket is made of?

Thanks for looking.

[zeke]

When I rebuilt my auto it was just a thin paper gasket

[TurnNburn]

yeah the thin paper gasket might still be attainable from Subaru but I good heavy duty RTV silicone will get the job done. That's what I used when I rebuilt my 5 speed.

[zeke]

Mine came with my rebuild kit I'm pretty sure you can get just that gasket

[RoughDiamond]

yeah the thin paper gasket might still be attainable from Subaru but I good heavy duty RTV silicone will get the job done. That's what I used when I rebuilt my 5 speed.

While it probably works for the 5MT, I would NOT use it on the auto. If you get any RTV in those passages, you are SOL. Or, when hardened, the clearance between the pump and the case could be uneven or too large causing thrust or bearing issues. Bad mojo.