The only way, and maybe not even then, is to take it out. You might be able to guess if the thermostat housing has been taken apart by telltale signs of excess gasket sealer in the area.
The thermostat is done it has to be replaced.......
it should be replaced when it stops doing its job controlling the temperature and replacing the battery does not solve the problem or it is showing a digital error code that tells you it is defective. You may also want to test if it actually is doing its job but the heating or cooling unit may be broken. If you have more than one zone and you know what you are doing, you can switch it with a known working thermostat and see if the problem stays with the zone or it moves with the thermostat. That should tell you if the thermostat is broken or the system related to that zone needs maintenance.
If the engine is taking a long time to warm up or the gauge registers low heat the thermostat probably is stuck open and needs to be replaced. If the engine runs hot check the temperature of the upper radiator hose. If it's not hot the thermostat is stuck closed and should be replaced. If the upper hose is hot it means the thermostat is open and working. Cooling problem could be restricted radiator.
brilliant, the thermostat is backwards
Can not be repaired, only replaced with the thermostat housing as one unit.
You don't. You replace a thermostat that has failed. They are meant to be replaced.
If the thermostat has failed it will need replaced.
had the same problem with a sibring,took to the garage,they replaced the thermostat and gasket and found a hairline crack in the thermostat housing they replaced the housing and everything was fine then
In general, engine thermostats can be found by following the LOWER radiator hose to where it attaches to the engine. The hose is typically attached to a fitting behind which is a gasket and the thermostat. The gasket needs to be replaced when the thermostat is replaced.
Blown head gastet, radiator leaking, thermostat needs to be replaced Blown head gastet, radiator leaking, thermostat needs to be replaced
Cracked.head
Check into the temperature control valve--this is different than the thermostat.