First of all just want to say hi this is my first post. I am trying to help a friend out and I am stumped. My friend has a 1994 taurus v6 and it is overheating just when she hits 2500 rpms about 70mph. She can cruse at 65mph with no trouble, but as soon as she goes 70mph it starts to overheat. Plenty of coolant and the water pump is about 2 years old. She took it to a mechanic and they told her it was the transmission which didn't sound right to me. Just wondering if anyone had a similar problem or could help. Thanks.

 

With the car being 12 years old, it probably wouldn't hurt to replace the thermostat and radiator cap. If the stat doesn't want to open (maybe because it's stuck), after you hit a certain speed, the stat can't help cool the engine at higher RPM's. The 2 parts work in conjunction with one another, so replace both....and it'll only cost you about $12-15 for a stat, cap, and stat gasket.