After replacing thermostat, why is temp gauge needle registering car is "cold" when driving on highway?
2001 Camry LE (4spd manual) 240K miles- original owner: car overheated -mechanic didn't find problem - said thermostat probably had gotten stuck. Car now had slight burning smell, added coolant every now and then. 3 months later, car overheated had water pump, thermostat changed, and since they were replacing things in the area and it was time, had timing belt changed too. Car temp gauge needle on highway stays on "C" (cold), and driving off highway, needle goes to center of gauge. Car smelled and felt like running hot in city driving - took car back & was told I was smelling the result of when it overheated. A week later, car over heated again, took car back and this time had to have motor oil pump changed & something to the head because they found shavings (??) , plus I told them thermostat was still not working right - please replace. They say it was replaced, I doubt it-gauge still behaves d same way. Car coolant level kept dropping low - couldn't figure out why. Took car back again, I asked for all hoses to be replaced (3 years ago replaced with new radiator and hoses changed). Still had smell and had added coolant more frequently and adding motor oil.
Went to 3 different mechanics - nothing. A couple of weeks later, a friend discovered - radiator cap threads were worn/stripped. I think this was the crux of the problem all along, coolant had been leaking from there.
However, thermostat needle still has never gone back to its normal position (in the middle of the gauge), car still has "overheating smell , needs oil almost every 200-500 miles (depending if it's highway or city driving), I have added coolant (from low level in reservoir) twice within last month, and new problem - when I turn on fan above low level, I hear a low rumble, and sound gets louder as I turn knob to higher level. HELP!!!!
NOTE: Both times when car overheated had (drove car for 1 - 2 minutes), car was towed to mechanic.