Cooling system diagnostics (Chevrolet Captiva 1)

Checking the Thermostat

1. Remove the thermostat from the car. Follow the step "Thermostat" in this section.

2. Make sure the valve spring is compressed when the thermostat is fully closed. If the spring is not compressed, replace the thermostat.

3. Suspend the thermostat and thermometer in a pan with a 50/50 mixture of ethylene glycol and water. Do not allow the thermostat and thermometer to sit at the bottom of the pan because uneven heat concentration at the bottom may affect the correct temperature reading.

4. Heat the tray with a torch.

5. Use a thermometer to measure the temperature of the heated solution.

6. The thermostat should begin to open at 87°C (189°F) and should be fully open at 102°C (216°F). If the thermostat does not open at these temperatures, replace the thermostat.

Engine overheating

Checkpoints	Operation, action
Check for coolant leaks.	Add coolant.
Check the concentration of the coolant solution.	The coolant solution should be a 50/50 mixture of ethylene glycol and water.
Check the front of the radiator for debris, leaves or insects.	Clean the front side of the radiator.
Check for leaks from hoses, coolant pump, heater, thermostat housing, radiator, plugs or cylinder head gasket.	Replace damaged components.
Check the thermostat for proper operation.	Replace the damaged thermostat.
Check the ignition lag.	Perform ECM code diagnostics. Check the integrity of the timing belt.
Check the functionality of the electric fan of the cooling system.	Replace the electric cooling fan.
Check the radiator hoses for clogs or wear.	Replace damaged radiator hoses.
Check the coolant pump for proper operation.	Replace the faulty coolant pump.
Check the condition of the expansion tank cap.	Replace the faulty expansion tank cap.
Check the cylinder head or cylinder block for damage or contamination.	Repair a damaged cylinder head or damaged cylinder block.

Coolant leak

Checkpoints	Operation, action
Check the radiator for leaks.	Replace the damaged radiator.
Check for leaks in the following areas: Expansion tank. Hose.	Replace the following parts as necessary. Expansion tank. Hose.
Check for loose or damaged radiator hoses, heater hoses and connectors.	Secure the hoses properly. Replace hoses or hose clamps.
Check the coolant pump seal for leaks.	Replace the coolant pump seal.
Check the coolant pump gasket for leaks.	Replace the coolant pump gasket.
Check the cylinder head tightness.	Tighten the cylinder head bolts to the specified values. Replace the cylinder head gasket if necessary.
Check for leaks in the following areas: Intake manifold. Cylinder head gasket. Cylinder block plug. Heat exchanger heater. Radiator drain plug	Repair or replace components to eliminate leak if necessary.

Engine does not reach normal operating temperature or cold air from heater

Checkpoints	Operation, action
Check to see if the thermostat is stuck open or the thermostat is the wrong type.	Install a thermostat of the correct type and heat range.
Check that the coolant level reaches the MIN mark on the expansion tank.	Add coolant up to the indicated mark on the expansion tank.