I have a 1994 Ford Explorer. A few weeks ago, it would not shift into Drive, so I found the transmission fluid low. I went and got some more fluid, added it (yes, in the right place!) and all was good... until a couple days later I experienced the same problem... added more fluid. And I also checked the engine oil... a quart and a half too much. I drained that much out and figured all was well... Until it started not shifting again. This time, I added 2 qts tranny fluid, saw it register on the dipstick, and drove off... Two days later I was again having problems after about 300 miles, the transmission fluid was low again and the engine oil was 2 quarts high... Coolant level has not changed throughout. How is the transmission fluid getting into my engine oil? What broke on my beloved Explorer? How much should this cost to get fixed? Thanks for the advice!

 

This is a common problem. The vacuum modulator on the transmission is leaking. The part is cheap. Trouble is it is right next to the exhaust pipe. Many have found it easier to remove the seat and go through the access panel. It is held in by one bolt and there is a center pin that will fall out. The fluid softens the hoses and you may need to add clamps up at the vacuum tree. Or you can pay a transmission shop to do the work.