Significant automatic transmission leaks

[jangell]

I put a quart of fluid in my automatic a month ago. Yesterday I put in another full quart when I noticed it slip slightly when cold. That can't be good.

After about 10 minutes of driving last night, I put some cardboard under the car. I checked it about 16 hours later, and I found this:
IMG_2484.jpg

I've marked up where I think the fluid dripped from here:
IMG_2486.jpg
- The centerline drops are just the low point where the leak collected before dripping down
- The pan isn't actually leaking (of any note, anyway) -- I cleaned that up quite well and properly torqued the bolts and everything. It's in very good shape. I think it's just that some fluid collected there and leaked off of it.
- The cooler is still leaking a little. I've just been dealing with it, because it's not leaking a lot.
- The majority of the leak seems to be coming from the driver's side of the final drive near the axle. The entire bottom of the torque converter housing (whatever that part of the trans is called) is wet. I think it's in a line because that cardboard was a bit warped, so it drained to the lowest point.

I want to be clear that I don't know if this is final drive fluid or transmission fluid. I'm thinking final drive fluid, but I'm not totally sure; I'm not good at identifying car fluids.

More pictures from under the car:
- Wet casing below the torque converter casing thing. You can also see the drips on the centerline near the drain plug for the final drive.
IMG_2487.jpg
- The leak has even gotten onto the subframe under the engine.
IMG_2488.jpg
- The pan looks fine. I think the liquid on it is just condensation (water). Not quite sure what those black oil-like flecks on the blue joint for the coolant hose are, though. It seems the e-brake line is rubbing against the edge of the pan, so it might be that it's wearing away/melting the rubber and causing it to "splash", but that doesn't seem right...
IMG_2489.jpg
- The ever-present trans cooler leak. I'll get that nut tight enough someday... or replace it with an alternate cooler.
IMG_2491.jpg
- Drips from the final drive. That black thing with the wires is the hall sensor for my speedometer. The green-brown fluid is final drive fluid.
IMG_2492.jpg

The thing is, this doesn't like like trans fluid to me, but rather gear oil. I replaced the driver's side drive flange a couple months ago, which did seem to reduce the leaking at that point, but this is notably worse. Today I raised the car up on all corners, making sure it was level, and removed the final drive fill plug, and immediately fluid poured out. I had filled this when I replaced the flange, and it was only full to the bottom of the fill hole.

My friend theorized that a seal between the transmission and the final drive has failed, and that transmission fluid is getting into the final drive, which in turn is forcing out the gear oil.

I'm tempted to remove the final drive fill plug and catch all the fluid that comes out, just to see how much extra is in there.

Has anyone seen this kind of thing before, and any idea what it might be? Is it some seal between the trans and final drive? I notice a lot of automatic transmission parts aren't available, and I don't want to buy another one (I'm on my fifth; I'm getting tired of this, and this one only has like 5k miles on it), so hopefully this is a fix that doesn't require special tools with available parts.

I was hoping I wouldn't have any real drivetrain problems for another 5 years or so, when electric conversions were more affordable and I could ditch this garbage transmission once and for all, but we're not quite there yet.

Thanks!

-- Joe

[Michael]

From your "droppings" that doesn't seem like a big enough leak to account for the loss you have experienced.

I would start by cleaning everything off very well with brake cleaner and going for a short drive then inspect the usual suspects first (dip stick seal, plug socket, cooler hoses). You may want to have a peek as soon as you stop while the engine is still running, then again in about 10 minutes after you shut it off.

If the main seal between the final drive is leaking, you should smell gear oil when draining the trans fluid. I don't think the trans fluid would go up to the final drive but gear oil would leak into the tranny. (I'm just guessing there but you can pull the top plug on the final drive and see if it's overfilled). You probably have an axle seal leaking as well as the trans leak but that in itself doesn't mean the main seal is leaking.


BEdit. Baaahhhh...I just read ALL of your post and it seems like you are one step ahead of me. Maybe trans fluid can leak onto the final drive.

[jangell]

I’m the kind of guy who writes really long posts, then starts replying almost as soon as I started reading another post, so no worries.

My mechanic friend suggested I pull the fill plug and see what I get. It emptied about 1/8 of a gallon jug. And the fluid was definitely more red than the greener gear fluid input in.

I drained the final drive completely and refilled I with new gear oil, 80w90. My friend suggested driving it for a few days, then checking how overfull the final drive is again. That should tell us how bad the failure is.

He also said he’s had this same failure in his Alfa Romeo Milano, and he’s confident we can fix it if the parts are available.

A shot of all the fluid that came out when I removed the fill plug:


— Joe

[Ron]

The trans fluid would mix quickly and thin the gear oil way down...Comparing the old gear oil to the new, was it a lot thinner?

I agree, one quart low shouldn't make it slip, normally. Could of been air since you don't know where the leaks are...

EDIT: How many miles for the 1 Qt?

[jangell]

Yes, much thinner. It easily poured out of the drive, and what I got on my hands felt thin, much more like ATF. Actually having new gear oil to compare it to made it obvious. The new oil took forever to get out of the bottle even after I drilled a hole in the bottle to relieve the vacuum. It took 5-10 minutes per bottle filling the drive. It took far less time to drain it.

— Joe

[Jonathan]

Best way I’ve found to determine what fluid it is that is leaking is to put a white plastic tray under the car instead of cardboard. I use a big one that started life as a meat and cheese tray for some SuperBowl party I had. Very easy to see if the fluid is bright pink or not that way.

The dipstick tube seal is another PITA that can leak a lot on the driver’s side.

[jangell]

I’ll keep that white plastic trick in mind.

The dipstick tube seal was a project earlier this year. Turns out that the replacement tube I got needed to be bent more to clear the body, or else it sat at an angle. After bending it a bit further it fit much better. I also used an otterstat gasket in placebos the o-ring. It works quite well now, with no leaks. At least there, anyway.

— Joe

[David T]

While it is possible for the transmission fluid to leak into the final drive, it is not a common failure especially if the transmission was never disassembled. If it was, then it is more likely. Make sure you are not overfilling the transmission. Follow the procedure in the manual. As for slipping when cold, replace or clean the filter. Any slippage is bad and you can destroy the clutch packs very quickly. Take a picture of the amount of debris in the pan when you drop it to change the filter. If you see a lot or you see ferrous metal, the transmission is done for. A little brass/bronze is OK along with friction materiel. Test the line pressure and do all of the external on car checks and adjustments.

[jangell]

Thanks David. I'll try to get the pan and filter off this weekend and see what it looks like. I'll check the manual for how to test the pressures. If I find the trans is wrecked, I'll just keep driving it until it stops working, I guess, since AFAIK it's impractical to repair them.

Since the car was off the road for 6 years, and the last trans I had was before that, I don't exactly remember the details, but I think this is the one where they were able to reuse the final drive and attach it to a new trans to bring the price down a bit. This means that it has come apart before, and may explain the leak.

One of the transmissions I had replaced was due to a weld failing (I had 1st but lost 2nd and 3rd), so I may just be a target for unusual failures.

As for slipping, every time it's happened it's been because the fluid is low. And the instant I notice it I check the level and put more fluid in -- I keep ATF in the trunk. I do the same if I feel like the car isn't rolling when I put it into gear from park, too. I've been trying to check it regularly, but I have a horribly time reading the dipstick It always seems either completely wet, with varying thicknesses of "wet", or (more rarely) completely dry, which happens when I notice a slip, but it seems I can never find the line when I try to read it. I can read the engine oil dipstick just fine; it's just the ATF dipstick I can never seem to manage.

I have destroyed transmissions before by not noticing the fluid levels, so I'm trying hard to keep it properly filled, but it's not making it easy.

-- Joe

[David T]

Best not to destroy the transmission, they can be rebuilt but not if you damage a lot of expensive"hard parts" like gears. Switching just the transmission is doable BUT. You must shim one of the clutches based on measurements from the final drive. Failure to do the swap properly will condemn the swap prematurely. And of course you must make sure you don't leak into the final drive. That is why it is best to replace the whole transaxle assembly in one piece.