[Mockspeed88]

So I decided to buy a Forester. It only has 92k on the clock. So the issue it has is when it gets warm for a while it stops shifting and the transmission appears to slip. The transmission fluid appears a little brown but doesn't have a burnt odor to it. Could this be a shift solenoid issue?
Reasoning is that the car runs and drives perfect upon startup but after getting to a operating temp and driving it, it appears to slip.

 

[bman400]

@Mockspeed88 Do the easy thing first before you start diving into messing with the shift solenoid. Drain and refill the ATF fluid 2-3 times so that it is no longer brown. It should be a cherry red/pink color.

The drain and refill means draining it from the pan drain plug, refill waht you drained out. Drive it around to get the fluid circulating, and then drain and refill again, drive it around. And repeat.

 

[Mockspeed88]

Yes that was on my list. I'm assuming it was probably never changed. I actually bought it off a old lady who it was her daily driver, and all of a sudden it just stopped driving, had it towed to a shop who had no idea and just wanted to swap it out with a rebuilt and then stated they don't know where to source one.

 

[bman400]

@Mockspeed88 The 4EAT Transmission is nearly bullet proof, unless it was abused. Like any Automatic Transmission, fluid is it's life blood. I can't tell you how many times in my 40 years of driving where AT issues clear-up when fluid has been changed.

 

[Fibber2]

One thing I would highly recommend when working on a 4EAT transmission from that era. Avoid so-called "Universal Transmission Fluids". Any fluid that claims to meet all specifications for a wide variety of autoboxes typically meets none. Subaru was rather specific, generally adhering to an older GM standard as they were sharing some engineering resources during that period in the company's history.

My 2002 Outback called out Dexron-III, and I had a near-disaster when I tried Maxlife. It slipped during acceleration, suffered from 'shift shock' when changing gears, and the fluid filled with black particles. I took several drain/fill cycles with a dedicated single spec Dex-III to get it back to where it was before I messed with it.

If you dive into the specs, Maxlife is a light fluid matching many modern fluids like Toyota WS with a Brookfield viscosity value of around 8500. Older Dex and similar era fluids were thicker, with a value of closer to 20,000. Add in the friction modifier differences, and you can easily make a mess out of a good transmission. Valvoline does market a Dex/Mer-III fluid, and I used that successfully. Try to find it or an equivalent.

Many have gotten good results with thin fluids, but horror stories abound. It's going to depend a lot on the condition of the clutch pack cellulose material, and whatever might be burned on to it. Mess it up, and you'll be headed for a full scale rebuild. So just my $0.02.....

 

[bman400]

+1 on What @Fibber2 states about Transmission Fluid, use either Dexron II or Dexron III. I have a 2001 with 230,000 miles on it. And I have only used Dexron II with it and never any issues. But I suspect Dexron II has now been replaced with Dexron III/IV.

 

[Mockspeed88]

Yeah I plan on using only a dex III fluid. I'm picking up the car tommorow. During my test drive it ran drive and shifted fine. But the woman I bought it from stated after driving it for a while it wouldn't shift and she had it towed. She took it to a domestic garage who states needs new trans. Which I don't think it does. I am definitely going to flush the system several times and do the method bman400 recommended.

 

[Fibber2]

I never needed this, but there were plenty of report of varnish build-up interfering with valve body operation. I know a few who used one of the BG flush operations to free things up. I'd call this a method of last resort if just a fluid exchange doesn't do the job.

 

[Mockspeed88]

What's the fluid capacity for the trans?

 

[bman400]

Some have stated 8oz less than 1 gallon. But other's have 4 quarts to 5quarts. Best is measure what you drained out and put back in the same amount as a reference point.

 

[Mockspeed88]

Well I picked up the car. So on startup it runs and drives fine. Then after warming up it doesn't move engine will just rev regardless of position of the gear selector. I scanned the computer got p0700 and p0741. The transmission fluid is almost black in color.

 

[Mockspeed88]

Well I did the fluid change, was very dirty, now fluid is clear and car will not move at all. I'm assuming something went internally, I sourced a trans locally for 1100 installed. So I paid 1000 for a one owner, rust free 05 with 92k on the clock. So I'm still ahead of the game