1. Make a visual check of the cooling system.
2. Ensure that the cooling system is full.

There is A visible external coolant leak.

Repair or replace the component(s) as necessary.

The radiator filler cap is damaged.

Replace the radiator filler cap.

The radiator is leaking.

Repair or replace the radiator. Refer to Radiator Replacement .

A leaking coolant recovery reservoir tank or hose.

Replace the coolant recovery tank or hose. Refer to Coolant Recovery Reservoir Replacement .

The following hoses, pipes and hose connections have loose or damaged components:

Reseat the hoses and clamps. If necessary, replace the hose(s), pipe(s) and the clamp(s). Refer to one of the following:

The thermostat housing is leaking?

Replace the thermostat housing gasket. If necessary, replace the thermostat housing. Refer to Engine Coolant Thermostat Replacement .

The front and/or rear heating system has a leaking heater core.

Replace the heater core. Refer to one of the following:

The intake manifold gasket is leaking.

1. Tighten the intake manifold bolts to specification. Refer to Fastener Tightening Specifications in Engine Mechanical-4.3L.
2. If the leak persists, replace the intake manifold gasket. Refer to Lower Intake Manifold Replacement or Upper Intake Manifold Replacement in Engine Mechanical-4.3L.

The cylinder head, the cylinder head gasket or the engine block is cracked or damaged?

1. Replace or resurface the cylinder head or engine block as necessary.
2. Replace the cylinder head gasket. Refer to Cylinder Head Replacement - Left Side or Cylinder Head Replacement - Right Side in Engine Mechanical-4.3L.