Location of 1998 Chevrolet S10 4.3 engine thermostat?
Follow the upper radiator hose from the radiator towards the engine. The upper radiator hose is connected to the thermostat housing on the engine side. The thermostat is under/inside the thermostat housing. Remove the upper radiator hose from the housing then remove the two bolts holding down the thermostat housing then remove the thermostat housing to expose the thermostat.
Should be located in a removable housing at the engine end of the upper radiator hose Drain about 1 gallon of coolant frm the radiator Remove this housing Note how thermostat is installed Clean both surfaces Replace thermostat and gasket Replace housing Re-fill coolant slowly to prevent an air lock Start engine and look for leaks Run engine to normal operating temperature with heater on Re-check coolant level