In order to showcase everything better instead of posting photos here, I made a video:
I have bought an overhaul kit from Aisin. It had all the teflon rings, o-rings, replacement bolts, seals and the transmission filter. Also next to it I bought a complete transmission friction disk set and new Toyota “World standard” oil. (Already tried the Volvo genuine on my last oil change, they are the same).
Ok, moving on to what I’ve found. After separating the tranny from the engine, everything looked ok, no weird smells, no rust, discoloration in the torque converter. So we went inside the tranny. The insides were honestly pristine. Checked the oil pump, it was like new. Mind you my car had around 110k miles at the time. Checked the solenoid valve Ohm values, all were in spec. Did not go into the solenoid valve body, as we thought it is too complex for us and that all the overhaul kits we have will fix the issues. So we went ahead and overhauled it. Changed the o-rings, changed the teflon rings that are responsible for the oil pressure. The old teflon rings have lost their elasticity and thus some of their function to seal. They were very brittle, while the new Aisin rings were much softer and flexible. There are probably around 10 of these teflon rings in various shafts in the transmission. Replaced all of them.
The oil filter which was not changed for all I know since the car was bought was actually ok. I couldn’t find any metal shavings inside of the old one, no sludge like the other guys in forum said I could find. Still went ahead and replaced it.
The friction plates however, some of them were a little discolored (darker) than the others. But not black or charcoal color. Measured their thickness and they were thinner than the new ones but they were still in spec.
After the repair, the transmission runs better, the shift are a little smoother and the car pulls stronger in first gears. For example, when standing still in Drive I can feel that I had to apply more pressure on the brake to keep the car still as it appears the new friction plates had more grip.
BUT.
The issue that I had before did not change at all. The chirping sound is still there, the cold start scooter issue is still there. Honestly, I cannot even feel that anything changed in that regard.
My thoughts are that the problem lies either in the torque converter (I think that’s not very likely) or in the worn valve body, solenoids or worn valve body valves.
I have bought a new OEM valve body from Aisin, which will arrive tomorrow. I’m planning to change the valve body this week to a new one and will come back to you with updates.