Repair-It

Probably going to try the cooler full change method. Assuming I can loosen all the plugs on the pan. Using Maxlife because I believe it is superior to the Toyota WS which reportedly isn't even a synthetic.

https://youtu.be/cB8MdGgwg68?si=3vjqt9nPr1EbZ_C3

According to one comment I can probably just fill from the other end of the disconnected cooler line. I bought a nice pneumatic power fill/extractor that I want to try. If I can get all the hoses hooked up this might be sweet. Only need to get under it for the initial drain and final level check. And cooler thermostat bypass and bypass removal when done.

I started by trying to loosen the check plug on the pan. This is a drain/fill/check from the bottom like Mercedes. Unlike Mercedes that uses a single plug for all three activities, Aisin uses three separate plugs. Large fill plug on the transmission case above the pan, a drain bolt and a check plug that is a higher level than the drain.

The check plug takes a 6mm allen key. I tried inserting it and no hope. Cleaned out the hole and was able to tape the socket into the check bolt. It seemed firm. Using my weakest Ryobi impact, I gave it some braps and it immediately stripped. I was starting to get nervous. Not wanting to give up I tried some female extractors around the check bolt. Too big or too small.

Last hope was vice grips. I locked them on and gave them a tap with a hammer and surprisingly the bolt loosened. Next I tried the drain plug which was a 14mm. This loosened with no issue. I didn't bother with the fill plug because I wasn't going to use that.

With a renewed sense of confidence I removed the drain bolt to drain the pan. I also staked the transmission cooler thermostat to the open position or else ATF wouldn't flow out of the hoses in the front. While that was draining I studied the cooler line situation at the front. Ended up removing one of the lines and connected on end to a hose that routes to a drain pan and the other I used to inject fresh fluid back to the pan. Put a new crush washer on a new drain plug and torqued it to 15 lb-ft. Used the old crush washer on a new check bolt and temporarily installed that.

Filled the dispenser with 2 gallons of ATF, pressurized it to ~40 psi and started injecting ATF into the return hose. After 3 or 4 quarts I stopped it and started the engine so it could pump the fresh fluid through the entire transmission, through the cooler and eventually out to my drain pan. It doesn't pump that fast so this was manageable and not messy.

I ended up running 12 quarts through and it seemed to be clean. So I let it pump itself mostly out of fluid and then injected the remaining 4 quarts. I figured this was a good plan because the manual says a pan drain only uses ~2.2 quarts. I just needed a little excess during the check procedure like on Mercedes so it can drain to the correct level at a set ATF temp.

Only problem was, when I fired the engine up and got it into level checking mode with my scan tool, and waited for the right temp, when I went to drain from the check plug, nothing came out. Oops. And I had used all 4 gallons. So off to O'Reilly's for more. Ended up adding another ~3 quarts using the same cooler hose method. Did the check process again and this time plenty came out, then down to a trickle. Threw a new crush washer on the new check plug and torqued to 15 lb-ft. Removed the cooler thermostat stake (paperclip).

Side note, it looked at first like the transmission cooler is HUGE, but upon closer inspection, most of that is A/C condenser. It is just built into one piece with the upper section being the transmission cooler. It goes go all the way across but is only 4-ish inches tall.

Did a road test and after some shifts to relearn it feels great. The shifting is cleaned up. Some of the clunky shifts are smoothed AND the torque converter shutter is gone. It accelerates more smoothly now. This made a pretty big difference. Very satisfying.