A55F (3speed) Transmission Problems

[sacwac]

I'm having trouble with my automatic transmission, it's slipping too much...

The main problem lies between the 2nd and 3rd gears. The upshift point into 3rd from 2nd is WAY too high (50mph under light acceleration), and it feels like its slipping for the couple seconds that the shift actually takes place. Also, once in 3rd, if you want to accelerate any more, it slips into 2nd. This slippage ALWAYS occurs after the engine and transmission have reached normal operating temps, but is still present when cold (just not so extreme).

The transmission fluid was BLACK when I got the car... I've changed it 2 times in a few months. I also removed the pan to change the filter, and there was literally a large handfull of sludge at the bottom of the pan, mostly of a thick greasy nature. There were also large clumps of "goo" around each of the 3 nickel-sized magnets. So there were metallic bits in the sludge, but they must have been very tiny.The filter was a little dirty, but not so much that it would totally block fluid transfer. I did replace both the filter and pan gasket.

The fluid is at the proper level, and the manual linkages into the governor are in proper adjustment. I've also run a stall test, with positive results being right on par with the specifications. I even did the pressure tests, as outlined in the factory repair manual.

Another thing I noticed was that the output shaft for the rwd wobbles inside the extension housing. Meaning, you can grab the shaft, and wiggle it. When you do this a little bit of fluid leaks out from the extension housing. I don't how the fluid circuits are setup inside the 4wd housing, but it could be a source of the low pressure.

Here is a summary of the transmission tests I performed:

data is, measured vs. (specification)

STALL TEST: OK
fwd 2,070 (2,050-2,350)
rev 2,040 (2,050-2,350)

GOVERNOR TEST: OK
1,000rpm 25psi @ 17mph (17-26psi @ 18mph)
1,800rpm 35psi @ 32mph (26-34psi @ 30mph)
3,500rpm 60psi @ 60mph (60-71psi @ 59mph)

LINE TEST: LOW
idle
fwd 60psi (57-65psi)
rev 105psi (107-121psi)
stall
fwd 110psi (132-161psi)
rev 220psi (252-287psi)

THROTTLE TEST: LOW
idle
fwd 0psi (0-4psi)
rev 5psi (0-4psi)
stall
fwd 80psi (110-118psi)
rev 100psi (110-118psi)

4WD: OK
off 0psi (0psi)
on 30psi (28psi)

Testing the transmission was kind of fun! I had the car up on 4 emergency stands, and had those wheels spinning. When all you have to do is spin the wheels, the tercel accelerates and stops VERY fast!


Car info:
1986 Toyota Tercel
3AC Engine
A55F Automatic Transmission (3speed 4WD)
175,000 miles

My guess is that the fluid has rarely or never been changed in the past, and that a valve in the transmission is clogged, or stuck, or that it's just all worn out. A bad oil pump might cause this, not pumping enough tranny fluid, and letting it overheat? Also, if the 4wd housing seal was leaking, a pressure drop might result?

What do YOU think?

[sacwac]

Oh I forgot to thank ICE for the previous advice to flush the transmission... I will do that soon and let you know how it turns out.

[sacwac]

I left out some important info about the diagnostic, when driving at low speeds in reverse, and in 4wd (forwards or backwards) there is MASSIVE shuddering. Never felt it with high speeds, just 0-5mph.

[takza]

What do YOU think?

As you might have noticed...I really don't know that much about auto transmissions...but here's what I think I know.

1) If the trans has gone 175K miles, it's probably done much better than most autos...have heard that they tend to start having problems around 120K miles.

2) With the amount of sludge you found in the pan...it's a wonder it works at all. ATF was never changed?

3) I wouldn't worry too much about the output shaft leakage except to keep the ATF level up...doesn't affect the line pressure.

4) If you changed it 2 times, you probably didn't really change all of the 2 quarts or so of ATF.

What I'd do:

Since the pan has a drain...just put it up on ramps and drain & replace the ATF 4-5 times with regular ATF every 300-500 miles or so? Then add 2 quarts Valvoline MAXLife ATF. This ATF is made for higher mileage trans and is supposed to cure the kinds of problems you mention (slipping and shuddering)...I have a bottle of it and it is thicker than regular ATF...improving your line pressure. While the flushing removes sludge & varnish. Don't forget the Lubegard...have seen it work.

For $25 to $30, you MIGHT get it to shift better & last a while yet.


Or ask this guy?

<a href='http://autos.groups.yahoo.com/group/aut ... nproblems/' target='_blank'>http://autos.groups.yahoo.com/group/aut ... oblems/</a>

Buy some parts?

<a href='http://aceomatic.com/catalog/automatics ... .asp?t=114' target='_blank'>http://aceomatic.com/catalog/automatics ... p?t=114</a>