Two problems related to transmission fluid leaking have been reported for the 2007 Mercury Mountaineer. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2007 Mercury Mountaineer based on all problems reported for the 2007 Mountaineer.
My 2007 Mercury Mountaineer never had any problems until recently, thought it was the transmission because of the way it drove. Took it to the mechanic and got transmission fluid put in but the problems remained the same and was told the transmission was fine. My thermostat housing unit was leaking (this is very common with these cars and very dangerous, needs immediate attention!) and had caused very expensive wiring issues. Almost acts exactly like the transmission is going out - rpm's are way too high, the vehicle would not accelerate in the middle of city traffic, the car jumped at a stoplight and caused me to hit the car in front of me, and it doesn't shift properly. Problems occurred out of nowhere and are too dangerous to be ignored but very expensive to be fixed. Its very common and should be recalled before someone gets seriously injured!!!!.
Apparently there have been a lot of issues with the thermostat housing leaking fluid into the electrical system causing it to short out. I was driving, went to take off in rush hour traffic and they vehicle wouldn't go because the leak and ruined a part of the electrical system and the gears would shift. It was almost like the transmission had gone out. I have read several accounts where this has happened to tons of <09 Mountaineers and explorers. TSB 09-22-15 came out about this issue. I was driving with my infant daughter and we could have been injured very badly. Something needs to be done about this. It has been identified and apparenlty affects people's cars and their ability to accelerate. Very dangerous.