AODE Leaking Tranny Fluid from back of tranny

[Chythar]

I just ran into this today. I went out to pick up a new rear bumper (mine is beat up), and was heading home on the freeway when I noticed a bit of smoke behind me. I changed lanes and it followed - yup, it was me. It was a bit light, until the freeway went uphill to pass over the Santa Monica mountains (for you SoCal Stangers, that's the 405 South just past the 101 freeway). Suddenly the smoke turned into a James Bond smokescreen. After cresting the mountain, the smoke died off and I didn't notice any smoke until I got home - a little drifting out behind the passenger's front wheel. I parked and checked under the car - noticeable dripping from the back of the transmission. The fluid was red, so it's tranny fluid. The smoke must have been tranny fluid burning on the exhaust.

I just added some tranny fluid last week, thinking I was low. So it's possible I overfilled the tranny. Or it could be the rear seal that went - I've been losing a bit of fluid now & then. I suppose the pan could be leaking. I can't check now, the car is WAY too hot from my drive. While the tranny was leaking, the Stang did NOT change at all. No shuddering, no slipping, nothing. Acted the same way it always does.

Can anyone else think of any other reason I'd be leaking tranny fluid? I'd like to get some ideas before I jack up the car tomorrow.

 

[revhead347]

I would get under the car and look at it. The tranny fluid could be coming from anywhere on the transmission, and running back to the tailshaft before it drips off.

Kurt

 

[Chythar]

I would get under the car and look at it. The tranny fluid could be coming from anywhere on the transmission, and running back to the tailshaft before it drips off.

Already planned, but I'll have to wait until tomorrow. Hopefully there'll still be enough fluid on the tranny to figure it out then.

 

[Bosko5.0]

Clean it up then drive up the road check for fluid if none then drive longer. My leak was the gasket between the trans and the output housing.

 

[HISSIN50]

Agreed that you just gotta look. A drop of trans fluid makes a LOT of smoke. I'd clean up and really watch the pan rails, cooler line fittings, VSS, and tail shaft. You should find it pretty quick.

 

[Chythar]

STATUS UPDATE

OK, I got a closer look at the transmission today. I first looked under the Stang to see if there was any fluid leaking. Several drops of tranny fluid on the ground, back by the tailshaft housing, but no puddle. This is after sitting overnight. The fluid was still a solid red, not dirty. I started the Stang and moved it a bit so I could get a jack underneath it. That Cervini's bumper makes it really hard to get a jack under there. I looked under the car again, and no new leaks.

I jacked up the GT and took a look around. Of course, there was reactor fluid -- er, tranny fluid all over. I scrubbed off as much as I could, and paid attention to where the tranny fluid (TF) was and wasn't.

No TF on the front of the tranny.
No TF on the driver's side of the tranny.
No TF on the tailshaft housing or the driveshaft yoke.

TF on the passenger's side of the tranny, towards the back.
A line of clean red TF on the passenger's side of the overfill valve at the top of the tranny. No other fluid on any other side of the overfill valve.
Both sides had TF from the crossmember back. Wind will whip the fluid EVERYWHERE, of course. But there was TF farther up the passenger's frame rail and some on the passenger's side of the midpipe. NONE in that area on the driver's side.

Seems obvious to me that the TF leaked out the overfill valve on the passenger's side. There may be other leaks, but some definitely came out the overfill valve up top. Time to drain the pan and see how much is in there. From what I've read, the AODE holds 11 quarts of fluid when DRY. A simple drain should only net about 3 quarts. I have a TCI deep aluminum pan which adds another 2 quarts. This means I should only be able to get out 5 quarts, right? I have an aftermarket tranny cooler as well, i don't know if that drains as well when you drain the tranny pan.

The TCI pan has a drain plug so draining the fluid was a snap. The fluid coming out was nice & red but there was sediment in it. That's not good. I don't know what's normal for an AODE but I do know my overdrive band slips if I accelerate too fast in overdrive. It holds if I'm nice to it.

So, I should have drained 5 quarts out of the tranny, about as much as an oil change. Any guesses how much I got?

9 quarts.

I measured using an old 4 quart and 1 quart motor oil containers, so I know I'm pretty close on the measurement. If the 5 quart capacity is correct, I've been WAY overfull for a while. I know I've had a hard time checking the fluid level for a while - the dipstick was always covered in fluid. Probably because I've been overfull.

Anyone want to correct me on the fluid level? Part of me is hoping that 9 quarts is the right capacity, another part is hoping it's wrong.

 

[Chythar]

Well, looks like 5 quarts it is. Hissin, I now see how to read the bloody dipstick. On my AODE, the part of the dipstick that is facing the firewall does NOT get tranny fluid from the dipstick tube on it. I checked at 3 and 4 quarts - the side away from the firewall had fluid on it, but the side facing the firewall was dry. After 5 quarts, both sides had fluid covering the "COLD" side but no higher. I should have checked at 4 1/2 quarts, but I forgot to. I'm sure the fluid level will change after I take the GT for a test drive, I'll check it again then.

Sanity check (relatively speaking): Did I miss anything? Anything else I should check?

 

[HISSIN50]

I never had the issue with a dry side on the dipstick. It is a PITFA to read though. With really fresh fluid, I would sometimes have to hold the edge of a papertowel perpendicular to the dipstick and run the towel towards the bottom of the stick. When I hit the actual fluid (and not smear), the paper towel would wick up the fluid.

Definitely check it when hot, after running it through all the gears. Hydraulic fluids expand with regard to temperature, and the hot level is what matters (plus it allows a stacked-plate cooler to more likely be full, or else the level will drop once the fluid thins enough to fit through the orifices).

 

[Chythar]

UPDATE

Took the GT for several test drives, and not a drop of tranny fluid leaking. The exhaust is still smoking a bit, burning off the rest of the old tranny fluid. I just checked the dipstick using Hissin's paper towel method, and the dipstick reads at the top of "FULL". Last night, the tranny read at the top of "COLD".

I decree the problem solved. A transmission WAY overfull (5+ quarts too many), and driving up a steep-enough incline resulted in tranny fluid pouring out the overflow valve on the top of the tranny.

The tranny has been overfull by at least a quart for a long time. I was unable to read the dipstick, it always said "FULL" even though it sometimes acted like it was low on fluid. I made a bad presumption, thought it was actually LOW on fluid and would add a quart. This actually would make the tranny behave again. I would guess that the fluid was foaming up by being too full and causing problems. Perhaps the added fluid would reduce the foaming - perhaps it was a coincidence. Now that I can actually read the dipstick, I won't let that happen again.

Of course, I'll be selling this GT in a month or two so it won't matter. More on that later.