As you guys already know:
Zetec Mystique
Initial problem: running hot
solution: replace ECT sensor.
My luck went all over the place here, had to end up using a pumbing wrench to get the old ECT out, and got the new one in. IMHO, it should probably go down into the hole further, but it wouldn't turn anymore, and it looks as if the old one stuck out a little too (no leaks), however now that this is taken care of, I've noticed a hissing sound after turning the car off - coming from by the firewall (I never listened for it inside the car, though).
Essentially, looks like I've got a vacuum leak.
I thought the air tube might not be quite on right, but double checked it and I doubt it's loose. It's not as if air would be leaking out of that with the car off, anyway!
The hiss runs for about 15-20 seconds after turning the car off, I assume it's there while running but can't tell for sure.
On the good side, the head gasket is okay - the AC runs cold like ice and the heat runs hot as hades. If there's anything else wrong with "overheating", it's either a low speed relay (doubt it seriously), or a bad temp sender (personally, I think they're both fine, the ECT was probably junk), who knows!
SOoo there we have it, any response is much welcome!
