I have been chasing a very slow transmission fluid leak on my 98 Expedition 5.4 4x4 and have not been able to isolate it until now. It leaks while sitting. I used a scope and it appears as if the leak is a seeping type leak, not a dripping type and might be where the transmission filler tube goes into the transmission, or possibly even the upper tube connection. It is a 2 part filler tube. One short part is pressed into the transmission and the main filler tube inserts into that.
I had a new main filler tube installed, but it appears as if the mechanic who installed it did not fit it all the way in.
The top of the filler tube neck is bent from mechanic trying to hammer it in, so I imagine he had a hard time to reinstall it, plus the upper mounting bracket does not line up with the block hole, so the tube is floating.
I noticed the leak after changing the fluid and gasket when I had a radiator problem. I had another thread about this, thinking it was a gasket or pan problem.
The leak appears on the rear of the pan, but it also feels wet on the top of the transmission where the pan mounts, so I think it is a traveling leak on top of the transmission, following the slope of the pan until it reaches the back of the pan, where it can accumulate enough to make drops.
I consulted a transmission shop, and he said it may be overfilled, which does make sense considering that the dipstick readings would be too high if the tube is not seated all the way. Transmission tech told me I should just level the vehicle and loosen the pan bolts until the fluid stops running out, keeping the upper limits of the cold fluid level at the top of the pan. I did this and ended up removing about 4 quarts.
Does this seem like a good approach? Letting the fluid drain out until level with top of pan? I leveled frame as a reference for level and drained from the back of the pan.