New Thermostat ?

[SDCORT]

2000 Land Cruiser. Headed up the mountains yesterday, wasnt really paying attention to my gauges ( I know I know ) until I pulled off the highway. At stop light, I noticed my heater gauge was at / around cold. Vent wasn't blowing HOT HOT air, maybe warm. Outside temp was around 10 degrees Fahrenheit. Pulled into parking lot and sat idling for about 30 min. Temp gauge rose. Lastly, when returning back down to Denver from the mountains, outside temperature was now around 45 degrees. Heater gauge seemed to be correct in dead middle. So, is this a classic example of thermostat stuck open ? Or something else ?

In replacing thermostat, its just 3 bolts, remove hose, catch as much coolant as I can, replace o ring, put new thermostat in, tighten 3 bolts. Pretty simple unless I'm missing something ? I've read threads about bolts breaking etc - but that appears to be when removing the actual housing not just the thermostat ?

 

[jsloden]

It will help if you drain down the coolant first. But yes, it's pretty much as simple as you described. I would get a genuine toyota thermostat. When you get it compare it to a generic one from autozone. The difference in quality will be obvious.

 

[nissanh]

Drain coolant from the drain plug at the bottom tank of the radiator. Use only OEM thermostat and the seal (it is really not an O-ring). The middle of the gasket has a grove and it should rest on the perimeter of the thermostat. If you suspect any pitting on the thermostat housing, order a new unit, it is not that expensive.