thermostat or waterpump?

[bionictony]

the temp gauge always stays a bit below half when normal.. about 45%. when i go uphill, freeway and street, the gauge goes to like 60% to 70%. when i'm going downhill the temp is normal. and when i'm on level surfaces the gauge moves from between 45% and 50%. sounds like a thermostat problem. i'm pretty sure there are no leaks. the cap is tight and the coolant tank stays about the same when cool and hot. the car is a stock dx with about 144k miles. is there any chance that the waterpump isn't working? i was told it should be replaced soon.

[whhcpdy]

I had a similar problem and my fan was not working properly you may get that tested. Also flush your coolant system.. if your coolant looks 'rusty' or 'milky' looking get a mechanic to check it out. Also see if the fins in the radiator are clean. I have checked my water pump operation by taking the radiator cap off while the motor is cold and start the car and let it idle till it gets to operating temp and you should see the water circulate. If the 'circulation ' is intermittant ...circulates for a few seconds and no activity for a minute then starts circulating again this is a good sign the thermostat is working. If the water never circulates and the temp gauge goes to normal or past (at idle) the thermostat could be stuck closed. Likewise if it circulates from the time you start it and never stops it could be stuck open. Best of luck! Andy