My 99 Mysteriously rolled in street HELP

I have a 99 Mercury Mountaineer. I have almost replaced every part this truck has to brand new, except for the ball joints. All with in a year and a half.
My problem is that between 1am and 5am last night my truck rolled out into the street, and sat there till I woke up in shock this morning to see it chillin in the street.
Yes I placed my truck in park. I am unable to get my keys out if it is not in park. What could have caused it to roll back? I just got all brakes done and brake lines done in February of 2009. My driveway is on a slight incline so it rolled on to the flat street.
I called around to as many dealerships as possible and they said I have a screw adjustment thing, that either needs adjusting or replacing. They would have to jack the truck up to do this. Is this correct? Can anyone tell me what this part is. I try to do my research before visiting a shop, but I am tired of mechanics trying to rip me off b/c I am a chic. Please help!!

Sarah

Did you set the parking brake, and is it possible the shops you called were under the impression that the brakes don't hold rather than that the transmission doesn't hold? When in park, the brakes really are out of the circuit except if you use the parking brake. But the parking brake is cable actuated rather than hydraulic (using the brake lines).

Also, does your Mountaineer have all-wheel drive (AWD) or 4-wheel drive (4WD)? Are the rear brakes drum or disc? If you have 4WD, the transfer case could have gone into neutral and allowed the vehicle to roll. I'm not sure if the AWD center differential/transfer case would be able to allow this or not. If you have rear disc brakes, the parking brake is a drum setup located within the rotor and completely separate from the normal hydraulic braking system.

If you have rear drum brakes, then the same shoes are used for the parking brake as the normal hydraulic brakes. They are still cable actuated, but that might explain what the shops are talking about with a "screw adjustment thing." Drum brakes use a threaded self adjuster to spread the brake shoes out to just before they make contact with the drum. If the adjuster is backed off too far, the parking brake will not be able to move the shoes far enough to hold the vehicle on an incline should the transmission/transfer case also fail to hold the vehicle stationary.

Were you able to start your Mountaineer up and drive it back into your driveway after this? Does it seem to hold on the incline?

-Rod

Ok lots of questions. I have parked in the same spot now for 6 months, everyday when I come home from work. I never use my parking brake. Now when I applied my parking brake last night, the vehicle did not move.

As for the AWD, thats another thing. lol. In March I got my radiator, waterpump, and hoses replaced. All brand new parts. Then in May all fluids drained from raditor. So I took it back to the shop on 05/22/09 and there was a leak behind my water pump, he fixed it and I picked it up, that late after noon. Immediately when I picked it I felt a different type of vibration. I drove it through the weekend, and the vibration was constant no matter what speed or street. ( I have the interstate memorized as to when I should feel a normal vibration and when I shouldnt feel anything) So I took it back on Tuesday after Memorial Day and the mechanic said my rear drive shaft was shot. He showed me this long huge thing that was rusted and the ball of it was done with. Needless to say the vibration immediately stopped.
I read a previous Mountaineer creeping, posted on here 10/2007, and it was because the front drive shaft was removed. SO I thought that means this situation doesnt apply to me. My car did not creep ever before, even after drive shaft removal. The other night was the first time.
To finish your last question, yes my vehicle started up immediately and it does hold on the incline. I am concern it will creep over a time frame.

After all this, what do I tell the mechanic to exactly check. Im tired of them going over everything and acting like they are doing me a favor by giving me a BS answer and then trying tell me what I am ganna do $1000 later.

Unfortunately after only one occurance that you haven't yet been able to repeat, it's very difficult to focus on only one area. You might have a shift linkage that is out of adjustment and not fully going in to park, but close enough that you were able to remove the key. You might have a parking prawl issue within the transmission. You might have a transfer case that has a problem internally. You might have forgot to put the truck in park, although I don't think you would have gotten your key out if that were the case.

Maybe for now you get in the habit of using your parking brake and turning your wheels to the curb when parking on an incline until you start experiencing other symptoms.

-Rod

yours only done it once lol, mine does it every day, my driveway is on a downhill incline and sometimes its all the way at the bottom of the field by the time i wake in the morning lol, unfortunately i have not found a solution to this problem

Hopefully you've started using your parking brake to at least slow it down if it tries to roll away.

-Rod