Diagnostic Routine B
Diagnostic Routine B
Diagnostic Overview
The Engine Overheats
Normal Operation and Fault Conditions
The engine cooling system maintains the engine temperature during operation. Correct coolant flow through the engine, radiator and remainder of cooling system passages and components is essential to maintaining a correct engine temperature.
Engine coolant flows primarily from the engine to the radiator circuit and back to the coolant pump. Coolant is sent from the coolant pump through the engine block and cylinder heads. A separate circuit from the engine also feeds the heater core with coolant. The coolant pump circulates the coolant. For 2.0L GTDI (Gasoline Turbocharged Direct Injection), the coolant pump operated by engine rotation through a pulley driven by the accessory drive belt. For 3.5L Ti-VCT (Twin Independent Variable Cam Timing), the coolant pump is operated by engine rotation through a sprocket driven by the camshaft timing chain. The coolant thermostat is a control valve actuated by coolant temperature. When the thermostat is closed, coolant flow bypasses the radiator circuit and returns to the coolant pump. When the thermostat is opened, coolant flows through the radiator circuit to transfer engine-generated heat to the outside air.
Engine overheating generally occurs when there is a disruption in the ability to control either coolant flow at the correct rate, the inability to transfer heat from the engine through the coolant (including low coolant) or an inability to transfer engine-generated heat to the outside air through the radiator. Engine overheating can be attributed to:
- Low coolant level
- External engine coolant leak
- Airlock in system
- Pressure relief cap installation
- Restricted airflow through the A/C (Air Conditioning) condenser/radiator
- Internal engine coolant leak
- Coolant condition/concentration
- Accessory drive components
- Non- OEM (Original Equipment Manufacturer) engine enhancement components
- Electric cooling fan
- Radiator
- Thermostat
- Temperature gauge
- Coolant pump
- Coolant flow restriction
REFER to System Diagram .
DTC (Diagnostic Trouble Code) Fault Trigger Conditions
Special Tool(s)
Material(s)
NOTICE: The cooling system is filled with Motorcraft(R) Specialty Green Engine Coolant or. Always fill the cooling system with the manufacturer's specified coolant. If a non-specified coolant has been used the cooling system must be chemically flushed. REFER to Cooling System Flushing . Failure to follow these instructions may damage the engine or cooling system.
NOTICE: Use Motorcraft(R) Specialty Green Engine Coolant or. Use the same type of coolant that was originally used to fill the cooling system. Do not mix coolant types. Mixing coolant types degrades the coolant corrosion protection and may damage the engine or cooling system.
NOTICE: Motorcraft(R) Specialty Green Engine Coolant is very sensitive to light. Do NOT allow this product to be exposed to ANY LIGHT for more than a day or two. Extended light exposure causes this product to degrade.
NOTE: During normal vehicle operation, may change color from orange to pink or light red. As long as the engine coolant is clear and uncontaminated, this color change does not indicate the engine coolant has degraded nor does it require the engine coolant to be drained, the system to be flushed, or the engine coolant to be replaced.
Pinpoint Test
WARNING: Always allow the engine to cool before opening the cooling system. Do not unscrew the coolant pressure relief cap when the engine is operating or the cooling system is hot. The cooling system is under pressure; steam and hot liquid can come out forcefully when the cap is loosened slightly. Failure to follow these instructions may result in serious personal injury.
1. CARRY OUT INSPECTION AND VERIFICATION
1. Carry out Inspection and Verification. REFER to Symptom Chart(s) Symptom Related Diagnostic Procedures.
Were any concerns found?
2. CHECK FOR AN AIRFLOW OBSTRUCTION
1. Check the radiator or A/C (Air Conditioning) condenser for an external obstruction such as leaves or cardboard.
Is an obstruction present?
3. CHECK THE ENGINE COOLANT LEVEL
NOTE: Allow the engine to cool before checking the coolant level.
1. Ignition OFF.
2. Visually check the engine coolant level in the coolant expansion tank.
Is the engine coolant level within specification?
4. PRESSURE TEST THE ENGINE COOLING SYSTEM
1. Pressure test the engine cooling system. REFER to Cooling System Pressure Test Cooling System Pressure Test.
Does the engine cooling system leak externally?
5. CHECK THE ENGINE COOLANT FOR AN INTERNAL LEAK
1. Inspect the engine coolant in the coolant expansion tank for signs of engine oil.
Is engine oil evident in the coolant?
6. CHECK THE ENGINE OIL FOR COOLANT
1. Remove the oil level indicator from the engine.
Is coolant evident in the oil?
7. CHECK THE COOLING SYSTEM FOR COMBUSTION GASES
1. Using 105R0110 (-) , following the instructions supplied with the tester, check the coolant for combustion gases.
Are combustion gases present?
8. CHECK COOLANT CONDITION
1. Check the coolant for dirt, rust or contamination and check the coolant concentration using ROB75240.
Is the coolant condition OK?
9. CHECK THE ELECTRIC COOLING FAN OPERATION
1. Start the engine.
2. Place the climate control function selector in the MAX A/C (Air Conditioning) position and the blower motor switch in the HI position.
Did the electric cooling fan operate?
10. CHECK THE COOLANT PUMP OPERATION
1. Start the engine.
2. Allow the engine to run for 30 minutes. Place the climate control function selector in the MAX HEAT position. Feel the heater outlet hose.
Is the heater outlet hose hot?
11. CHECK THE THERMOSTAT OPERATION
1. Start the engine.
2. Allow the engine to run for 30 minutes. Feel the lower radiator hose.
Is the lower radiator hose hot?
12. VISUALLY INSPECT THE THERMOSTAT
1. Carry out the thermostat visual inspection. REFER to Thermostat Thermostat.
Is the thermostat damaged?
