2001 Subaru Outback "Overheating " Problems

I have a 2001 Subaru Outback (2.5 L, 4 Cylinder Engine). Lately, I have been having trouble with the car ?overheating.? Whenever, I drive it around in 70 degree weather or below and between approx. 25 mph and 45 mph, the temperature gage will go from being halfway to the ? mark and it stays at the ? mark. It does not matter if the AC is on or off and it will not act do it when it is warm (I live in Phoenix so the mechanics I take it to have not been able to duplicate the problem). When I step on the accelerator hard, the temperature gage will immediately drop back down to normal but will also go back up within a couple of minutes if I continue to drive as described above. If I drive at normal highway speeds, the temperature will eventually go down to normal.



I have had to replace the head gaskets in this car already (6 months ago) and my mechanic has checked them and they appear to be fine. When the head gaskets were replaced the timing belt, water pump, and thermostat were all replaced too. The radiator has also been checked and cleaned out. And the fans have been checked and they work. Does anyone out there have any idea what may be going on?



Thanks!

I would guess the trouble is due to a faulty thermostat. If you replace it I suggest you use a OEM unit.

Or maybe it is just the gauge indication that it is running cool when it is really up to normal temp.

I would check the thermostat first, as it usually is easy to check.