Check the reservoir cap, you probably need a new one. could also be a blown head gasket blowing compression into the radiator
Leaking radiator radiator hose head gasket water pump Heater core thermostat housing
Low coolant? Radiator plugged or restricted? Water pump not circulating coolant? Thermostat not opening? Cooling fan not working? Hoses collapsing under pressure Defective radiator cap?
If it's overheating, it cold be thermostat, radiator or possibly other problems. If it's not overheating it could be the coolant level sensor.
To replace the thermostat on a 91 Cavalier you need to drain the radiator. Remove the top radiator hose and water inlet. Remove the thermostat from under the inlet. Install the new thermostat and reinstall the inlet and hose. Fill the radiator with fresh antifreeze.
Low coolant? Thermostat not opening? System airbound? Radiator plugged or flow restricted? Defective radiator cap? Water pump not operating? Clutch or cooling fan not working?
Once the thermostat has opened, the hot coolant flows from the thermostat housing on the engine into the top of radiator and out the bottom of the radiator back into the water pump.
The most common cause of overheating is a thermostat stuck in the closed position. Other causes of overheating could be a clogged radiator, faulty water pump, a faulty radiator fan relay, a faulty radiator fan motor, no coolant or low coolant level.
Low coolant, failed thermostat, inoperative radiator fan, failed waterpump, failed head/headgasket, etc.Low coolant, failed thermostat, inoperative radiator fan, failed waterpump, failed head/headgasket, etc.
Connected to the upper radiator hose. Coolant flows from the engine to the radiator to be cooled. The coolant temp. sensor should be screwed into it.
1. Check coolant level 2. Check to see if you have heat in the cabin 3. Feel the hoses and see if you feel any coolant passing thru them. Be careful the hoses can be hot. 4. Your thermostat may be stuck not allowing coolant to circulate 5. Your water pump has quit and will not circulate the coolant even with a good thermostat.
Follow the top radiator hose from the radiator . The hose connects to the engine coolant thermostat / water outlet assembly bolted to the engine . The engine thermostat is inside the housing
Run engine to normal operating temperature witout radiator cap Observe coolant circulation If coolant blows out of radiator - could be a stuck thermostat If no circulation could be a bad water pump