Where is the thermostat on a 1990 geo prizm?
Just follow your top radiator hose from the radiator to where it
attaches to the engine. This is your thermostat housing. Drain the
radiator, take the hose clamp loose, remove the two 10 mm nuts from
the housing and GENTLE tap the housing. This will expose the
thermostat to you. Make sure you get a new gasket along with the