Hi. I'm new to the forum. I've owned my 1991 Legacy Wagon for over 12 years. When I bought it I had the transmission almost 100% rebuilt. Now, 120,000 miles later (245,000 total) the transmission is behaving very strangely.

 

Randomly it will disengage at all different speeds. If I stop, turn the ignition off and restart, it will re-engage. It doesn't do it every day, but when it does do it I might have to turn off and start several times on the way home.

 

The first time I check tranny fluid and it was low. It was also dark. I didn't change the fluid but did add new fluid to appropriate level. That seemed to help for a while, but now behavior is the same but tranny fluid is fine.

 

I'm not sure it' worth investing in repairs at this point, unless it's something simple, which I doubt.

 

Thoughts?

 

Thanks!

The trans fluid should have been changed half way through those miles. autos are very sensitive to the fluid. Hydraulic fluid will break down by time and mileage more so than other fluids and can cause problems. The fact that you can turn the car off and restart means you most likely have a problem with the shift solenoids in the valve body. If the key cycle didnt help i'd lean towards fluid or clutch related issues deeper in the trans. If it's electrical you should have a stored code. I'd recommend reading this thread.

 

http://www.ultimatesubaru.org/forum/showthread.php?t=117234

I believe the tranny fluid was changed somewhere near 50000 after the tranny job.

Just a thought. Since this is an electronic transmission either the transmission control unit, TCU, or that fan-shaped whatever on the side of the transmission could be the problem.

i used to have a spare TCM from my m/t swap but it got rained on

The TCU or TCM actually sounds like an easier fix. Is it? I wouldn't be doing it myself, but any repair more than $200 is not worth it considering the mileage.

grab one from a junk yard

Is it an easy swap? I'm relatively good at mechanics. Just not a lot of time.

 

thanks!

TCU should be easy to swap. Its under the dash somewhere I think. Either that or under the carpet on the passenger floor/ foot panel.

Called my mechanic and he said I could try a friction modifier. If that doesn't work then it may be time to hang it up.

 

Can't seem to find much info about the TCU online.

TCUs in Subarus rarely go bad.

 

Just sayin'

 

I don't even bother pulling them when scrapping cars. Same with ECU's on Subaru's.

 

I have had decent success with Lucas transmission fix in a variety of cars. Again for me Subaru tranny issues have been rare.

Friction modifier? That brings to mind stuff like Slip Lock or Posi-Trac Limites slip addtives. DO NOT use Slip Lock or other such friction additives designed for clutch type limited slip differentials. Those make it EASIER for the clutches to SLIP. Additives of that type will ruin an automatic transmission in no time.

 

You could try an additive such as Lucas Transmission Fix, or K&W Trans-X Stop Slip, or other type of fluid that is designed to prevent slipping. But.....

Since the transmission engages properly after restarting the engine it certainly seems like an electrical problem and a fluid additive will likely not help.

 

First things first, change the fluid entirely. Any fluid that meets Dexron III spec will work. I usually buy the store brand Multi-Vehicle fluid or Dex/Merc mix whichever is cheaper. Drain and refill 3 times (roughly 4 quarts will drain each time) with a short drive in between. Some people go for 20 - 30 miles. I drive for about 3 minutes. I've even just idled the engine for a minute or two and shifted through all the gears before draining/filling again. The point is the same, get most of the old fluid out, which can't be done by draining just once.

I am having this same issue in my 99, but mine also slips while moving, especially when changing gears under load. Lucas did basically nothing to help. Pull the solenoids and clean them?

Make sure you aren't over full. Drain the pan, add 3 1/2 quarts of atf and a bottle of trans-x and see if that helps.

That didn't help, if anything its worse now...

i did the same for my 97 and it took about a week of driving and it cleared right up. it's like a whole new wagon again.

Ok, I wont give up yet, will probably flush it a couple more times, the fluid was pretty nasty.

if it was super nasty, your solenoids are sticking. The proper course of action is to replace the trans with another used one because of the varnish has eroded the walls of the valve body. Good used ones can be had for just a few hundred dollars or less, just get one from a wrecked car or JDM.

 

You may be able to get away with a valve body swap but if the friction material in the clutches are affected, it's just a band aid.

 

Drive it around and maybe it will clear up.

 

Subaru recommends a pan drain and fill every 30 to 60k miles.

It was pretty dark, ive seen worse. It slips pretty bad, especially right after it shifts gears, it will just rev up like its in neutral. Ive only had the car a week, so I don't know how well it was maintained...