Not sure what vehicle you're asking about but on most it will be in a metal housing usually held on with two bolts and to find that all you have to do is look for the radiator hose Thea does NOT go to the water pump and look sat the end of that hose that does NOT go to the radiator and you should fond the housing at the end. So... Look for the radiator and follow the big hose away from the radiator and you'll either find the water pump of the thermostat housing. Good luck. More detail as to the specific vehicle will help next time.
It Depends On What Kind Of Thermastat You have
Thermastat
You may have installed the thermostat backwards.
Should be in a removable housing at the engine end of the upper radiator hose
Need to change your thermastat i have done that but still over heats when driving
coolant tempure sensor,thermastat
How do I change a thermastat on a 2004 dodge stratus se ?
Behind of Carburetor air filter collector, you have to take this off and them is behind
Need to change your thermastat i have done that but still over heats when driving
you might need a thermastat. my 98 was doing the same thing. its easy and cheap to replace.
over other stuff jump on the lamp and there is a thermastat try turning it
thermostat is located under the exhaust manifold at the rear of engine and held by 2 10mm bolts