To replace the thermostat, remove the housing cover, note the installation, remove the thermostat, clean the gasket surfaces, and install the new thermostat. Apply sealant to the new gasket, reassemble, refill the cooling system, and check for leaks. For DOHC models, remove the battery and air filter housing, disconnect the radiator hose, remove the thermostat housing bolts and old gasket, note the old thermostat's installation, remove it, install the new one with the jiggle valve up, and reassemble.