For 1990-2009 cars only
- Drain only enough coolant so that the level is just above the top of the cylinder head. Refer to Cooling System Draining and Filling .
- Disconnect the radiator inlet (upper) hose.
- Remove the coolant thermostat. Refer to Engine Coolant Thermostat Replacement .
- Remove the accessory drive belt. Refer to Drive Belt Replacement in Engine Mechanical 4.3L.
- Start the engine. Increase the engine speed (RPM) several times, while observing the coolant level. Any noticeable rise in the coolant level or the appearance of bubbles may show that exhaust gas is leaking into the cooling system.
- If bubbles are present or the coolant level rises noticeably, replace the head gasket. Refer to Head Gasket Replacement in Engine Mechanical.
Notice: Allowing the drive belt tensioner to snap into the free position may result in damage to the tensioner.
