The meter on my dash was reading low even after driving for 20 minutes on a sunny day. Then all of a sudden it jumped over the 270 mark. I have a relatively new thermostat could my water pump have gone bad? I did not see any leaking coolant or anything under the vehicle.
Either the water pump... Or it could be the radiator that might not be performing as well.
It sounds like the thermostat was stuck open from the last drive cycle, and thats why your car wouldn't warm up, then it sounds like (somehow) it is now stuck closed. The only way to be sure is to feel for any large differences in temperature before and after the thermostat to see if its stuck.
Generally, a water pump won't stop pumping unless the belt is off. The usual water pump problem, that requires replacement, is when the shaft seal starts leaking coolant. A thermostat, on the other hand, can work normally, or maybe stick open (makes getting heat in the winter very slow) or maybe stick closed (overheat within a few minutes of starting the engine, and blowing coolant out of the tank). The coolant level (in the engine/radiator) could be low. Don't look when the engine is hot.
first check the coolant level, make sure it is full, this may be all it is, it could also be the thermostat went bad, this is not that unusual for a new thermo. to fail, make sure the belt to the pump is good, unlikely the pump is bad if it is not leaking or making any noise at all! but, when the new thermo. was installed did you purge all the air from the system, at times and in some autos air will become trapped and you have to bleed the air out of it, some have a bleeder screw and some don't, the ones that do not have a bleeder then you have to raise the front end of the car to the point where the radiator top is higher than the engine and make sure the heat is turned on and set to high!
first check the gauge and the sensor are working properly
