Initial Inspection and Diagnostic Overview

Inspection and Verification





Special Tool(s)

CAUTION: To avoid personal injury, do not unscrew the coolant pressure relief cap while the engine is operating or hot. The coolant system is under pressure; steam and hot liquid can come out forcefully when the cap is loosened slightly. Failure to follow these instructions can result in personal injury.

CAUTION: Check the coolant level and engine oil, top off the coolant if needed, if there is engine coolant in the engine oil the cause must be corrected and oil changed or major component damage may occur.

1. Verify the customer's concern by operating the engine to duplicate the condition.





2. Inspect to determine if any of the following mechanical or electrical concerns apply.
3. If the inspection reveals an obvious concern that can be readily identified, repair it as necessary.
4. Inspect the coolant condition.
1 Inspect the coolant color.
- If premium Engine Coolant VC-4-A or equivalent meeting Ford specification ESE-M97B44-A has a clear, light green or blue color, this indicates a higher water content than required.
- Dark brown could indicate unauthorized stop leak may have been used. Use Motorcraft Cooling System Stop Leak Pellets E6AZ-19558-A (Motorcraft RA-2) or equivalent meeting Ford specification ESE-M99B37-B5 except as noted in ES-F65E-19A511-AA only.
- A light or reddish brown color indicates that rust may be present in the cooling system. Flush the system and refill with the correct mixture of Premium Engine Coolant.
- An iridescent sheet on top of the coolant could indicate a trace of oil is entering the system.
- A milky brown color may indicate that engine oil is entering the cooling system. If engine oil is suspected, the cause of the leak may be internal to the engine.

2 If the engine coolant appearance is acceptable, test the engine coolant freezing point with a fluid tester. The freezing point should be in the range of -50° F to -10° F. If the vehicle is driven in cold climates less than -34° F. it may be necessary to increase the coolant concentration to get adequate freeze protection.
- Maximum coolant concentration is 60/40.
- Minimum coolant concentration is 40/60.

3 Adjust coolant range and level if necessary.
- If coolant is low, add specified coolant mixture only.
- If the engine coolant tests too weak, add straight engine coolant until the readings are within acceptable levels.
- If the engine coolant tests strong, remove the some of the engine coolant and add water until the readings are within acceptable levels.

5. If the concern remains after the inspection, determine the symptom(s) and go to the Symptom Chart. Symptom Related Diagnostic Procedures