The car is a 2000 Lincoln LS--automatic transmission.

The car was acting strange...then it over-heated. All of the coolant had leaked out. I replaced the fluid so I could get it to the shop. Then the car would not change gears at higher speeds.

When I brought it to dealership service dept. they opened to hood and saw that someone had put a screw in a radiator hose--possibly to plug a leak? I had no idea someone did that.

Originally, the said they would replace some radiator hoses and look at the transmission. Initially, they came up with an estimate of about $1800. (for the hoses, and attempt to repair the transmission) The dealership kept the car for several days...they called me to tell me--they couldn't repair the transmission--but they could replace it for about $4000. They said that who ever put that screw in the radiator, caused the car to overheat, and thus ruined the transmission. I decided not to have them fix the transmission...but it still costed me $1200!! They said the car is undriveable. They said they replaced hoses and put in new solenoids.

My question is: Is it possible that the car over-heating (though it was not driven after got "hot") could ruin the transmission?