The kickdown cable port on the TH350 transmission is a common issue. This week, I decided to put an end to this leaky madness.
In Japan, especially in the city, there are so many traffic lights and stop signs, that the kickdown can actually be completely removed. That makes it really easy to cap.
The plastic cable mounts needs to be removed.
The cable the actuates the internal kickdown mechanism will also have to be removed, and that can only be done by dropping the pan.
Once the pan is removed, the cable can be accessed. Use some pliers to twist the cable off the lever.
The Plastic mount is what we need to properly plus the leaky port. I used an M7 x 1.0 Tap, a transmission fluid safe o-ring and M7 plug to create a custom cap.
I used the O-ring on the bottom side, where the mount mates with the transmission body. Leave the top hat shaped seal that was on the mount to begin with.
I also coated the threads on the plug with Permatex black RTV sealant.
With the new cap in place, the leak was completely cured, and the transmission could be filled to the proper level.