Component Tests and General Diagnostics

COOLING SYSTEM INSPECTION

Note: Check the coolant in the coolant recovery reservoir and radiator, if vehicle has not been allowed to reach normal operating temperature. This will make sure sufficient coolant exchange has occurred.

1. Allow the engine to cool and remove the radiator cap.
2. Inspect the coolant in both radiator and the coolant recovery reservoir for coolant color:
^ Clear light green or blue indicates higher water content than required.
^ Dark brown indicates possible use of unauthorized stop leak.
^ A light or reddish brown color indicates rust in the cooling system. Flush the system and refill with the correct mixture of water and engine coolant.
^ An iridescent sheen on top of the coolant indicates a trace of oil is entering the cooling system.
^ A milky brown color indicates that oil is entering the cooling system.
^ A reddish milky appearance indicates transmission fluid is entering the system.

Caution: If there is coolant in the engine oil, the cause must be corrected and the oil changed or engine damage may occur.

3. The causes of the leak might be:
^ A blown head gasket.
^ A cracked or warped cylinder head.
^ A crack in the engine oil gallery and the cooling passage ways.
4. The causes of other leaks might be:
^ A leaky radiator.
^ A leaky transmission fluid cooler.
5. Drain the fluids and repair or replace as required. Add the proper mixture of water and engine coolant.
6. If the coolant appearance is OK, test the coolant range.
^ Maximum range is 60/40.
^ Minimum range is 45/55.
7. Coolant system conditions:
^ If the cooling system is low, top off only with a premixed solution.
^ If the coolant mixture is weak, add straight coolant until the readings are within acceptable levels.
^ If the coolant mixture is strong, remove some coolant and add water until the readings are within acceptable levels.