I have a 93 Aerostar with 105k on it with the 4.0 automatic. Recently I saw fluid in the drive and crap all over the back window. Jacked it up and noticed the tranny was leaking thought it was the lines took them off inspected them put them back on seemed fine. Didn't leak but if I drove it far enough or long enough it will start just leaking fluid bad smoking down the highway from it getting on the exhausted. Could it be a seal? It seems like it just leaks when something's got enough pressure on it. Tranny has always shifted fine. Any pointers or suggestion. Can't really tell where it's leaking from.
Thanks.
Hunter

 

Most probably the trans modulator being that it is on top of the exhaust. You will find it with a small hose attached to it on passenger side. Also check the rear seal by the drive-shaft.

 

If it's leaking only under load, it's probably the front seal. But the rear seal and modulator are easy things to check first, and replace if necessary.

 

If the transmission is overfilled and subjected to high heat- from towing or blocked transmission cooler - the fluid will expand significantly and come out of the overflow drain line. Check the opening of the metal line coming vertically down alongside the transmission on the driver's side and see if there are any drops of residual fluid. Running a Q-tip up the opening or touching the opening with a piece of Kleenex will show reddish discoloration if fluid has recently come through that line. Alternatively, you can place white paper at various locations underneath the transmission overnight to see where the leak(s) are occurring.

There are other threads on this forum with the same problem and symptoms. Might try a search but I find the search feature almost useless when searching the sister forums for problems with my other Ford trucks.