Initial Inspection and Diagnostic Overview

Special Tool(s)

Inspection and Verification

WARNING: To avoid personal injury, do not unscrew the coolant pressure relief cap while the engine is operating or hot. The cooling system is under pressure; steam and hot liquid can come out forcefully when the cap is loosened slightly.

CAUTION: Check the coolant level, engine oil and transmission fluid. Top off the coolant if needed. If there is engine coolant in the engine oil or transmission fluid, the cause must be corrected and oil/fluid changed or major component damage can occur.

CAUTION: Do not mix coolant types.

1. Verify the customer concern by operating the engine to duplicate the condition.
2. Inspect to determine if any of the following mechanical or electrical concerns apply.





Visual Inspection Chart

3. If the inspection reveals an obvious concern that can be readily identified, repair it as necessary.
4. Inspect the coolant condition.
^ If Motorcraft Premium Gold Engine Coolant VC-7-A (in California and Oregon VC-7-B, in Canada VC-7-C) (yellow-colored) or equivalent meeting Ford specification WSS-M97B5 1-A1 has a clear or pale yellow color, this indicates higher water content than required.
^ Dark brown could indicate unauthorized stop leak may have been used. Use Motorcraft Cooling System Stop Leak Pellets VC-6 or equivalent meeting Ford specification ESE-M99B37-B6.
^ 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 distilled water and Motorcraft Premium Gold Engine Coolant (yellow in color). Refer to Engine and Radiator Flushing.
^ An iridescent sheen on top of the coolant could indicate a trace of oil is entering the system.
^ A milky brown color may indicate that either engine oil or transmission fluid is entering the cooling system. If transmission fluid is suspected the cause may be a leaky radiator. Pressure test the cooling system.
^ If transmission fluid is contaminated with engine coolant the cause may be a leaky radiator. Pressure test the system.
^ If the engine coolant is black (diesel only), the coolant level may have been low at a previous time. The Exhaust Gas Recirculation (EGR) cooler may have failed and exhaust gas may be contaminating the coolant.
^ If the engine coolant appearance is acceptable, test the engine coolant freezing point range with the battery and anti-freeze tester. The freezing point should be in the range -40°C to -20°C (-50°F to -10°F). If the vehicle is driven in cold climates lower than -32°C (-26°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.

^ 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 some of the engine coolant and add distilled water until the readings are within acceptable levels.

5. If the concern remains after the inspection, determine the symptom(s); Refer to Symptom Related Diagnostic Procedures