I recently bought a really sweet 92 240 wagon, the overdrive was not
working. the light would turn on and off with the button, but the
solenoid wasn't working. What I found was the top of the solenoid was
melted off. Since I live in flat Florida, and have no need to turn
overdrive off, I did the fix where you cut a groove between the two
holes in the solenoid  and discard the innner O ring. This worked
perfect, I have been driving the car for four days now, and overdrive
works perfect. However, the other day we did a 150 mile highway trip
in it, at speeds of around 85mph. The car ran flawlessly, except after
we got off of the freeway, it did not shift back into overdrive again,
I stopped, checked the fluids, and everything looked fine, when I took
off again all was well, overdrive was working. The only thing out of
norm here, is I seem to be about a half quart high on fluid, and it
has been this way since I bought it. When hot, it covers the entire
plastic thing on the end of the dipstick.  Could this be causing me
problems? could this be a heat issue? should I put a cooler on? what
do you think.
Jerry