I have a high milage '98 forester. After a long period w/ very steady low temperature readings, I was 120 miles into a trip yesterday when it started to rain. I was driving up a mountain in 5th gear at around 2400 rpms and I noticed that my gauge was getting hot. It would then cool off when I shifted to 4th and brought the RPMs up to 3k. This went on for the next 50 miles-- every time the car got below 2800 rpms it would go to about 3/4 the way to red.
So today I noticed that the coolant was low. I took it to an auto parts store and a guy who worked there had a Subaru said that it was likely a bad thermostat. I bought one and changed it. I refilled the radiator and when it got hot enough for the fan to come on after 15 minutes or so, the temp guage really spiked. (BTW I could not tell for sure if the old thermostat was bad)
I tried to drive it and had to stop really quickly since it was getting close to the red--much closer than yesterday.
It didn't exactly seem hot but I am not really sure.
Could this occur if I didn't properly bleed the air out of the system? Does this sound like the pump may be bad? The guage? Any advise before I go to a mechanic that I cannot afford?
Thanks, Matt