Initial Inspection and Diagnostic Overview

1. Once pressure is released remove the pressure relief cap. Allow the engine to cool and remove the pressure relief cap.

WARNING: NEVER REMOVE THE PRESSURE RELIEF CAP WHILE THE ENGINE IS OPERATING OR WHEN THE COOLING SYSTEM IS HOT. FAILURE TO FOLLOW THESE INSTRUCTIONS CAN RESULT IN DAMAGE TO THE COOLING SYSTEM OR ENGINE OR PERSONAL INJURY. TO AVOID HAVING SCALDING HOT COOLANT OR STEAM BLOW OUT OF THE DEGAS BOTTLE WHEN REMOVING THE PRESSURE RELIEF CAP, WAIT UNTIL THE ENGINE HAS COOLED, THEN WRAP A THICK CLOTH AROUND THE PRESSURE RELIEF CAP AND TURN IT SLOWLY. STEP BACK WHILE THE PRESSURE IS RELEASED FROM THE COOLING SYSTEM. WHEN YOU ARE SURE ALL THE PRESSURE HAS BEEN RELEASED, (STILL WITH A CLOTH) TURN AND REMOVE THE PRESSURE RELIEF CAP.

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

NOTE: Check the engine coolant in the degas bottle and radiator, if vehicle has not been allowed to reach normal operating temperature This will make sure sufficient engine coolant exchange has occurred.

2. Inspect the coolant in both the radiator and the degas bottle for coolant color:
- Clear, light green or blue indicates higher water content than required.
- Dark brown indicates unauthorized stop leak may have been used. Use cooling system Stop Leak Powder E6AZ-19558-A or equivalent meeting Ford specification ESE-M99B170-A only.
- A light or reddish-brown color indicates rust in the cooling system. Flush the system and refill with the correct mixture of water and Premium Cooling System Fluid, E2FZ-19549-AA or equivalent meeting Ford specification ESE-M97B44-A.
- 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.
- 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 passageways.

- The causes of the leak might be:
- A leaking radiator
- A leaking auxiliary fluid cooler.

- If engine coolant is present in the engine oil, the cause of the leak might be:
- A blown head gasket
- A cracked or warped cylinder head.
- A crack in the engine oil gallery and cooling passageways.

- If engine coolant is present in the transmission fluid, the cause might be:
- A leaking radiator.
- A leaking auxiliary fluid cooler.

3. If the engine coolant appearance is good, test the engine coolant range with the battery and antifreeze tester:
- maximum range is 60/40.
- minimum range is 45/55.

4. Check the engine coolant system conditions:
- If the engine cooling fluid is low, add specified coolant mixture only.
- If the engine coolant fluid tests weak, add straight engine coolant until the readings are within acceptable levels.
- If the engine coolant tests strong, remove some of the engine coolant and add water until readings are within acceptable levels.