Rather than replace it just take it out and see if it fixes it, then if it does buy one (so you don't waist any more money than you have to).

 

+1.

its a $18 OEM part, and with a new timing belt/WP 2.5k miles ago, might as well do it.

sounds like the culprit.

oh, and mitsubishimike has a point, but with all the time and pain in the ass is it to change, might as well just replace it.

 

+1 this is right ive had the same problem many times. sounds like thermostat is stickin. but where is the water going? you guys have to remember he's losing water. i know when mine stuck it would build pressure and it keept blowin heater core hose. thats where my water was going check that.if you change the thermostat and the water still goes down check all hoses. thermostat might have blew out a hose or ussally hoses under pressure the hose clamp will rip it. you might have two problems thermostat and a hose. g/l man

 

well, i am really unsure how but it seems to have fixed itself. the coolant isnt mysteriously disappearing and the car is no longer overheating. i was about to change the thermostat and checked the fluid, it had not gone down. both hoses get hot and fan seems to come on now. i think i had hella air in the lines and it was making the ecu think it was hotter (air heats up faster than liquid obviously) and thus pushing more fluids (also my oil seemed a bit low so maybe it was pushing more fluid)to compensate. Whatever it is, I am no longer losing fluid and the overheating problem seems solved. Does my theory sound plausible? Let me know. Thanks