Cooling System Leak Testing (Exhaust Gas Leak Test)

NOTICE: Exhaust gasses may enter the cooling system through a leaking cylinder head gasket. Exhaust gasses combine with water to form acids. These acids are harmful to the cooling system and the engine.

In order to check for exhaust gases leaking into the cooling system, do the following steps:

1. Drain the coolant system until the coolant level stands just above the top of the cylinder heads. Refer to Draining and Filling Cooling System.
2. Disconnect the upper radiator hose. Refer to the appropriate procedure:
^ Radiator Hose Replacement.
3. Remove the thermostat. Refer to Thermostat Replacement.
4. Remove the drive belt. Refer to one of the following procedures:
^ Drive Belt Replacement in Engine.
5. Start the engine and accelerate several times.
6. Inspect the coolant level for the appearance of bubbles or a significant rise in the coolant level. If the coolant level rises or bubbles appear, coolant may be leaking into engine. Inspect the spark plugs. Refer to Spark Plug Visual Diagnosis.