temp. gauge going high!!!

[french02chris]

i need some help!!
i drove from orlando to miami (and back) over the week-end, when i noticed a problem with the engine temperature.
in daily driving with a/c ON...the needle stay a bit below middle.
but this week-end, the faster i was driving, the higher the needle went...so basically, i could not go over 70 mph..(at 70mph,the temp was 3/4 high), but i soon as i slowed down or stop, then the needle would go back to below middle....the radiator is full of coolant, the reservoir also, both hoses are pretty new,the timing belt has been replaced 22k miles ago....and the fans are running...the only thing is that i had to drive with the a/c OFF!!
so what could be the problem??????????
thank you....

[Mazdawarbird]

When was the last time you checked your thermostat? Could possibly be stuck. Or it could be as simple as engine friction from overused oil.

[StealthWyvern]

How hot has it been in orlando area.. that has a lot to do with it as well. My old mystique cut off due to the high heat of the summer while going 85 down I4. If I kept it around 65-70 it would run fine. All fluid levels were fine and so was the t-stat.

After I got it back upto jacksonville it ran fine for another 60k miles tell i blew the engine due to no oil. So it might just be the heat of the summer.

[french02chris]

i don't think it is due to the heat of the summer...i had this car for 5 yrs already in orlando,and it never happened b4....i guess that i might have to replace the thermostat and i was thinking the water pump also!?

[mazpro]

that's weird, it should be the other way around. the faster you go, the more air there is cooling the radiator... hmmm

my car's temp has been going up a lot lately, but mostly when i run it hard. I will be doing a radiator flush to see if it helps any.