One problem related to transmission solenoid has been reported for the 2005 Mercury Mountaineer. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2005 Mercury Mountaineer based on all problems reported for the 2005 Mountaineer.
Minimal events lead up to transmission failure. Odd shifting when accelerating occurred the day of the failure and possibly several times overt the tow years, but very infrequently. Failure occurred at 74,000 miles of primarily highway driving with perhaps two reverses a day resulting at most 2,000 reverses for the life of the car. The same day as shifting problems occurred several times on the way home reverse gear would not engage and after several attempts would stay in gear for only a few seconds before going back into neutral. Never would go into reverse again. Failure required replacement of the solenoid shifters and valve bodies. This is the same failure that was a cause for a recall of several previous year's, including 2004.