Ford Explorer Quiz
Powertrain

Diagnosis and Testing - Engine Cooling

In this manual: Powertrain
General Information — 41Chassis — 173Powertrain — 250Electrical — 303Body and Paint — 331
19steps
~119min
5/5difficulty
1special tools
Done 0 of 19

Special Service Tools)
Coolant/Battery Refractometer
ROB75240 or equivalent
D-Gas Adapter
300-OTC014-R1068 or equivalent
Radiator Tester
014-R1072 or equivalent
UView® Combustion Tester
UVU560000-R

Diagnostic Trouble Code (DTC) Chart

NOTICE: Use only the correct coolant. Do not mix coolant types. Mixing coolant types can reduce the corrosion protection of the coolant and can damage the engine or the cooling system. For the correct coolant for this vehicle, refer to Specifications.


REFER TO: Health and Safety Precautions (100-00 General Information, Description and Operation).

The diagnosis in this manual assumes a certain level of skill and knowledge of Ford-approved diagnostic procedures.
REFER TO: Diagnostic Methods (100-00 General Information, Description and Operation).


Diagnostic Trouble Code Chart


Module Trouble Code Description Action
PCM P0125:00 Insufficient Engine Coolant Temperature for Closed Loop Fuel Control GO to Pinpoint Test C
PCM P0128:00 Thermostat Engine Coolant Temperature Below Thermostat Regulating Temperature GO to Pinpoint Test C
PCM P0217:00 Engine Coolant Overtemperature Condition GO to Pinpoint Test B
PCM P1299:00 Cylinder Head Overtemperature Protection Active GO to Pinpoint Test B

Inspection and Verification

NOTICE: Always fill the cooling system with the specified coolant. Chemically flush the cooling system if a coolant not meeting the specification was used. Failure to follow these instructions may damage the engine or the cooling system.

  1. Verify the customer concern.
  2. Visually check the engine coolant level in the coolant recovery reservoir when the system is cold.
  3. Make sure the pressure relief cap is installed correctly.
  4. Record all cooling system diagnostic trouble codes (DTCs). Refer to the PCM DTC Chart in this section for DTC descriptions.
  5. If the cooling system is filled correctly and no fail-safe cooling related DTCs are retrieved, verify the customer concern by starting the engine to duplicate the condition.
  6. Visually check for obvious signs of mechanical or electrical damage.

Visual Inspection Chart


mechanical Electrical
  • Leaks or seepage from:
    • Hoses
    • hoses
    • Clamp connections
    • Gaskets
    • O-rings
    • Thermostat Housing
    • Radiator
    • Pressure Relief Cap
    • Coolant Pump
    • Cabin heater coolant pump
    • Heater core (wet floor or coolant smell in the vehicle)
    • Oil Cooler (internal or external leakage possible) (if equipped)
    • Transmission Fluid Warmer (internal or external leakage possible)
    • Transmission Fluid Warmer Control Valve
    • Lower Intake Manifold
    • Degas bottle
    • Engine Block Core Plugs
    • Cylinder Head Core Plugs
    • Engine Block Heater (if equipped)
  • Cracks or damage:
    • Hoses
    • hoses
    • Clamps
    • Thermostat Housing
    • Lower Intake Manifold
    • Oil Cooler (internal or external leakage possible) (if equipped)
    • Transmission Fluid Warmer (internal or external leakage possible)
    • Transmission Fluid Warmer Control Valve
    • Radiator
    • Pressure Relief Cap
    • Fan
    • Coolant Pump
    • Cabin heater coolant pump
    • Degas bottle
    • Engine Block Core Plugs
    • Cylinder Head Core Plugs
    • Engine Block Heater (if equipped)
  • Restricted airflow through the A/C condenser/radiator
  • Drive belt loose, worn or incorrectly installed
  • Broken or loose drive belt tensioner
  • Excessive white or light gray exhaust smoke (may have a burnt coolant smell)
  • Coolant in Engine Oil
  • Coolant in the transmission fluid
  • Engine oil in the coolant
  • Transmission fluid in the coolant
  • Inoperative or damaged:
    • Electric cooling fan
    • Wiring, connectors, relays or modules
    • TP Sensor
  1. If the inspection reveals an obvious concern that can be readily identified, correct as necessary.
  2. Inspect the condition of the coolant.
    1. Check the color of the coolant.
      • A darker color with debris may indicate that a commercially available stop-leak product may have been used. This can cause a loss of coolant flow to critical engine components. If sediment is present, flush the system and refill with the correct mixture of distilled water and the specified concentrated antifreeze/coolant.
        REFER TO: Engine Cooling System Flushing (303-03A Engine Cooling - 2.3 L EcoBoost (201 kW/273 L PS), General Procedures).
        REFER TO: Specifications (303-03A Engine Cooling - 2.3 L EcoBoost (201 kW/273 L PS), Specifications).
      • A light or reddish-brown color indicates rust may be present in the cooling system. Flush the system and refill with the correct mixture of distilled water and the specified concentrated antifreeze/coolant.
        REFER TO: Engine Cooling System Flushing (303-03A Engine Cooling - 2.3 L EcoBoost (201 kW/273 L PS), General Procedures).
        REFER TO: Specifications (303-03A Engine Cooling - 2.3 L EcoBoost (201 kW/273 L PS), Specifications).
      • A rainbow sheen on the surface of the coolant may indicate oil contamination in the system. For engine diagnosis,
        REFER TO: Engine (303-00 Engine System - General Information, Diagnosis and Testing).
        Flush the system and refill with the correct mixture of distilled water and the specified concentrated antifreeze/coolant. REFER TO: Engine Cooling System Flushing (303-03A Engine Cooling - 2.3 L EcoBoost (201 kW/273 L PS), General Procedures).
        REFER TO: Specifications (303-03A Engine Cooling - 2.3 L EcoBoost (201 kW/273 L PS), Specifications).
      • A milky brown color may indicate that engine oil has entered the cooling system. Pressure test the cooling system. Refer to the component tests in this section. If engine oil contamination is suspected, the leak may be inside the engine. For engine diagnosis,
        REFER TO: Engine (303-00 Engine System - General Information, Diagnosis and Testing).
        Flush the system and refill with the correct mixture of distilled water and the specified concentrated antifreeze/coolant. REFER TO: Engine Cooling System Flushing (303-03A Engine Cooling - 2.3 L EcoBoost (201 kW/273 L PS), General Procedures).
        REFER TO: Specifications (303-03A Engine Cooling - 2.3 L EcoBoost (201 kW/273 L PS), Specifications).
    1. If the appearance of the engine coolant is acceptable, check the engine coolant freeze point range with a coolant/battery refractometer. Maintain the coolant concentration.
      REFER TO: Specifications (303-03A Engine Cooling - 2.3 L EcoBoost (201 kW/273 L PS), Specifications).
    1. If necessary, adjust the coolant range and level:
      • If the coolant level is low, add only the specified coolant mixture.
      • If the engine coolant is too weak, remove some of the engine coolant and add the correct concentrated antifreeze/coolant until the readings are within acceptable limits.
        REFER TO: Specifications (303-03A Engine Cooling - 2.3 L EcoBoost (201 kW/273 L PS), Specifications).
      • If the engine coolant is too strong, remove some of the engine coolant and add distilled water until the readings are within acceptable limits.
  3. If an obvious cause for an observed or reported concern is found, correct the cause and verify proper system operation before proceeding to the next step.

Symptom Chart

The diagnosis in this manual assumes a certain level of skill and knowledge of Ford-approved diagnostic procedures.
REFER TO: Diagnostic Methods (100-00 General Information, Description and Operation).

Condition Possible Sources Action
Coolant Loss Refer to Pinpoint Test GO to Pinpoint Test A
Engine Overheats. Refer to Pinpoint Test GO to Pinpoint Test B
Engine Does Not Reach Normal Operating Temperature. Refer to Pinpoint Test GO to Pinpoint Test C
The heater module is not operating correctly.
  • Heater Module Power Cable
  • Heater Module
  • CHECK the continuity of all 3 power cable circuits. If the resistance of any circuit exceeds 5 Ohms, INSTALL a new power cable.
  • CHECK the resistance of the heater module. If the resistance is not between 30 and 40 ohms, INSTALL a new heater module.
    REFER to: Heater Module (303-03A Engine Cooling - 2.3 L EcoBoost (201 kW/273 L PS), Removal and Installation).
Electric Cooling Fan Inoperative at one or more speeds or operates incorrectly.
  • Wiring
  • Relay
  • Fuses
  • Cooling Fan Motor
 Refer to the Powertrain Control/Emissions Diagnosis (PC/ED) manual.
Electric Cooling Fan Runs Continuously.
  • Wiring
  • Relay
 Refer to the Powertrain Control/Emissions Diagnosis (PC/ED) manual.
Noisy electric cooling fan operation.
  • Foreign Material Contamination
  • Blower motor
  • REMOVE the foreign material from the cooling fan and shroud. CHECK the system for proper operation. If still noisy, INSTALL a new cooling fan module.
    REFER to: Engine Cooling Fan Motor and Shroud (303-03A Engine Cooling - 2.3 L EcoBoost (201 kW/273 L PS), Removal and Installation).
  • Cooling fan blades disconnected from the fan motor
  • INSTALL a new cooling fan assembly.
    REFER to: Engine Cooling Fan Motor and Shroud (303-03A Engine Cooling - 2.3 L EcoBoost (201 kW/273 L PS), Removal and Installation).

Pinpoint Tests


PINPOINT TEST A: COOLANT LOSS

Normal Operation and Fault Symptoms

The engine cooling system is a closed system. It allows for expansion and contraction of the coolant, and changes in pressure, as the coolant heats and cools during engine operation. Various gaskets, seals, hoses and clamps retain the coolant within the cooling system and prevent other fluids and contaminants from entering the cooling system.

Possible Sources

  • Coolant Hoses or Tubes
  • Clamps
  • Thermostat O-Ring or Gasket
  • Coolant Pump O-Ring or Gasket
  • Thermostat Housing
  • Oil Cooler (internal or external leakage possible) (if equipped)
  • Transmission Fluid Warmer (internal or external leakage possible)
  • Transmission Fluid Warmer Control Valve
  • Radiator
  • Pressure Relief Cap
  • Coolant Pump Weep Hole Leaking
  • Cabin heater coolant pump
  • Heater Core
  • Lower Intake Manifold
  • Engine Gaskets (internal or external leakage possible)
  • Degas bottle
  • Engine Block Core Plugs
  • Cylinder Head Core Plugs
  • Engine Block Heater (if equipped)
WARNING: Always allow the engine to cool before opening the cooling system. Do not remove the coolant pressure relief cap while the engine is running or the cooling system is hot. The cooling system is under pressure; steam and hot coolant can be expelled forcefully when the cap is loosened. Failure to follow these instructions may result in serious injury.
A1 INSPECT AND VERIFY
  • Inspect and verify.

Is there a concern?
Yes REPAIR as necessary.
No GO to A2
A2 CHECK THE ENGINE COOLANT LEVEL AND PRESSURE TEST THE ENGINE COOLING SYSTEM
  • Ignition OFF.
  • Visually check the engine coolant level in the degas bottle and adjust if necessary. Pressure test the engine cooling system. Refer to Component Tests, Cooling System Pressure Test in this section.

Is there an external leak in the engine cooling system?
Yes REPAIR or INSTALL new components.
No GO to A3
A3 CHECK THE ENGINE COOLANT FOR INTERNAL LEAKAGE
  • Inspect the engine coolant in the degas bottle for signs of engine oil.

Is engine oil visible in the engine coolant?
Yes
REFER TO: Engine (303-00 Engine System - General Information, Diagnosis and Testing).
No GO to A4
A4 CHECK THE ENGINE OIL FOR COOLANT CONTAMINATION
  • Remove the engine oil dipstick.

Is engine coolant visible in the engine oil?
Yes
REFER TO: Engine (303-00 Engine System - General Information, Diagnosis and Testing).
No GO to A5
A5 CHECK THE ENGINE COOLANT FOR TRANSMISSION FLUID CONTAMINATION
  • Check the engine coolant in the degas bottle for signs of transmission fluid.

Is transmission fluid visible in the engine coolant?
Yes INSTALL a new transmission fluid warmer.
REFER to: Transmission Fluid Cooler (307-02A Transmission Cooling - 10-Speed Automatic Transmission - 10R60, Removal and Installation).
REPAIR the transmission as necessary. REFER to: Symptom Chart Diagnosis (307-01A Automatic Transmission - 10-Speed Automatic Transmission - 10R60, Diagnosis and Testing).
CHECK the system for proper operation.
No GO to A6
A6 CHECK THE TRANSMISSION FLUID FOR ENGINE COOLANT CONTAMINATION
  • Remove the transmission fluid level plug.
  • Check the transmission fluid for engine coolant contamination.

Is engine coolant visible in the transmission fluid?
Yes INSTALL a new transmission fluid warmer.
REFER to: Transmission Fluid Cooler (307-02A Transmission Cooling - 10-Speed Automatic Transmission - 10R60, Removal and Installation).
REPAIR the transmission as necessary. REFER to: Symptom Chart Diagnosis (307-01A Automatic Transmission - 10-Speed Automatic Transmission - 10R60, Diagnosis and Testing).
CHECK the system for proper operation.
No GO to A7
A7 CHECK THE COOLING SYSTEM FOR COMBUSTION GASES
  • Using the Cooling System Combustion Gas Tester, follow the instructions supplied with the tester, check the engine coolant for combustion gases.

Are combustion gases present?
Yes
REFER TO: Engine (303-00 Engine System - General Information, Diagnosis and Testing).
No Cooling System Operation
PINPOINT TEST B: ENGINE OVERHEATS

Normal Operation and Fault Symptoms

The engine cooling system maintains engine temperature during operation. Correct coolant flow through the engine, radiator and the remainder of the cooling system passages and components is important to maintain correct engine temperature.

Engine coolant flows mainly from the engine to the radiator circuit and back to the coolant pump. Coolant is sent from the coolant pump through the cylinder block and cylinder heads. A separate circuit from the engine also supplies the heater core with coolant. The coolant pump circulates the coolant. The coolant thermostat is a control valve operated by coolant temperature. When the thermostat is closed, coolant flow bypasses the radiator circuit and returns to the coolant pump. When the thermostat opens, coolant flows through the radiator circuit to transfer engine heat to the outside air.

Engine overheating normally occurs when the coolant flow cannot be controlled to the correct rate, when heat cannot be transferred from the engine to the coolant (including low coolant level), or when heat generated by the engine cannot be transferred to the outside air through the radiator.

DTC Fault Trigger Conditions

Trouble Code Description Fault Trigger Condition
PCM P0217:00 Engine Coolant Overtemperature Condition Set in the PCM when the CHT sensor detects an engine overheat condition.
PCM P1299:00 Cylinder Head Overtemperature Protection Active Set in the PCM when the CHT sensor detects an engine overheat condition.

Possible Sources

  • Low coolant level
  • Engine coolant external leakage
  • Air trapped in the system
  • Pressure relief cap installation
  • Restricted airflow through the A/C condenser/radiator
  • Engine coolant internal leakage
  • Coolant condition/concentration
  • Non-OEM engine enhancement components
  • Electric cooling fan
  • TP Sensor
  • Radiator
  • Thermostat
  • Coolant Pump
  • Restricted coolant flow
  • Active grille shutter assembly
B1 INSPECTION AND VERIFICATION
  • Complete the inspection and verification procedure described in this section.

Is there a concern?
Yes REPAIR as necessary.
No GO to B2
B2 CHECK THE PCM (POWERTRAIN CONTROL MODULE) FOR DTCS
  • The ignition is on.
  • Using a scan tool, perform the PCM self-test.

Is DTC P0217 and/or P1299 present?
Yes GO to B4
No Actual engine overheating is not confirmed. CHECK the operation of the engine coolant temperature gauge.
REFER to: Instrument Cluster, Message Center and Warning Chimes (413-01 Instrument Cluster, Message Center and Warning Chimes, Diagnosis and Testing).
If any other PCM DTCs are present,
REFER to: Engine Control Modules (303-14C Engine Control Modules - 3.3 L Duratec-V6/3.3 L Duratec-V6 - Hybrid (BP), Diagnosis and Testing).
B3 CHECK FOR ACTIVE GRILLE SHUTTER DTCS
  • Review the PCM DTCs.

Are any active grille shutter DTCs present?
Yes
REFER TO: Active Grille Shutter (501-02 Front End Body Panels, Diagnosis and Testing).
No GO to B4
B4 CHECK FOR AIRFLOW OBSTRUCTION AND MISSING AIR DEFLECTORS
  • Check the radiator or A/C condenser for external obstructions, such as leaves or cardboard, and make sure all air deflectors are in place.

Is there airflow obstruction or are air deflectors missing?
Yes REPAIR as necessary.
No GO to B5
B5 CHECK THE ENGINE COOLANT LEVEL AND PRESSURE TEST THE COOLING SYSTEM
  • Ignition OFF.
  • Visually check the engine coolant level in the coolant recovery reservoir and adjust if necessary. Pressure test the cooling system.

Is there an external leak in the engine cooling system?
Yes REPAIR or INSTALL new components.
No GO to B6
B6 CHECK THE ENGINE COOLANT FOR INTERNAL LEAKAGE
  • Inspect the engine coolant in the coolant recovery reservoir for signs of engine oil.

Is engine oil visible in the coolant?
Yes
REFER TO: Engine (303-00 Engine System - General Information, Diagnosis and Testing).
No GO to B7
B7 CHECK THE ENGINE OIL FOR COOLANT CONTAMINATION
  • Remove the engine oil dipstick.

Is engine coolant visible in the engine oil?
Yes
REFER TO: Engine (303-00 Engine System - General Information, Diagnosis and Testing).
No GO to B8
B8 CHECK THE ENGINE COOLANT FOR TRANSMISSION FLUID CONTAMINATION
  • Check the engine coolant in the degas bottle for signs of transmission fluid.

Is transmission fluid visible in the engine coolant?
Yes INSTALL a new transmission fluid warmer.
REFER to: Transmission Fluid Cooler (307-02A Transmission Cooling - 10-Speed Automatic Transmission - 10R60, Removal and Installation).
REPAIR the transmission as necessary. REFER to: Symptom Chart Diagnosis (307-01A Automatic Transmission - 10-Speed Automatic Transmission - 10R60, Diagnosis and Testing).
CHECK the system for proper operation.
No GO to B9
B9 CHECK THE TRANSMISSION FLUID FOR ENGINE COOLANT CONTAMINATION
  • Remove the transmission fluid level plug.
  • Check the transmission fluid for engine coolant contamination.

Is engine coolant visible in the transmission fluid?
Yes INSTALL a new transmission fluid warmer.
REFER to: Transmission Fluid Cooler (307-02A Transmission Cooling - 10-Speed Automatic Transmission - 10R60, Removal and Installation).
REPAIR the transmission as necessary. REFER to: Symptom Chart Diagnosis (307-01A Automatic Transmission - 10-Speed Automatic Transmission - 10R60, Diagnosis and Testing).
CHECK the system for proper operation.
No GO to B10
B10 CHECK THE COOLING SYSTEM FOR COMBUSTION GASES
  • Using the Cooling System Combustion Gas Tester, follow the instructions supplied with the tester, check the engine coolant for combustion gases.

Are combustion gases present?
Yes
REFER TO: Engine (303-00 Engine System - General Information, Diagnosis and Testing).
No GO to B11
B11 CHECK THE ENGINE COOLANT CONDITION
  • Check the engine coolant for dirt, rust or contamination and check the engine coolant concentration.

Is the engine coolant condition satisfactory?
Yes GO to B12
No FLUSH the engine cooling system.
REFER to: Engine Cooling System Flushing (303-03C Engine Cooling - 3.3 L Duratec-V6, General Procedures).
B12 CHECK THE ELECTRIC COOLING FAN OPERATION
  • Start the engine.
  • Set the climate control function selector to MAX A/C and the fan switch to HI.

Did the electric cooling fan operate?
Yes GO to B13
No CHECK the operation of the electric cooling fan. Refer to the Powertrain Control/Emissions Diagnosis (PC/ED) manual, Section 3 Symptom Charts.
B13 CHECK THE COOLANT PUMP OPERATION
  • Start the engine.
  • Run the engine for 30 minutes. Set the climate control function selector to MAX HEAT. Feel the heater outlet hose.

Is the heater outlet hose hot?
Yes GO to B14
No INSTALL a new coolant pump.
REFER to: Coolant Pump (303-03C Engine Cooling - 3.3 L Duratec-V6, Removal and Installation).
B14 CHECK THE THERMOSTAT OPERATION
  • Start the engine.
  • Run the engine for 30 minutes. Set the climate control function selector to MAX HEAT. Feel the radiator lower hose.

Is the radiator lower hose hot?
Yes CHECK the operation of the temperature gauge.
REFER to: Instrument Cluster, Message Center and Warning Chimes (413-01 Instrument Cluster, Message Center and Warning Chimes, Diagnosis and Testing).
No GO TO B15
B15 VISUALLY CHECK THE THERMOSTAT
  • Perform a visual inspection of the thermostat in the Component Testing section of this section.

Is the thermostat damaged?
Yes INSTALL a new thermostat.
REFER to: Thermostat (303-03A Engine Cooling - 2.3 L EcoBoost (201 kW/273 L PS), Removal and Installation).
No INSTALL a new thermostat.
REFER to: Thermostat (303-03A Engine Cooling - 2.3 L EcoBoost (201 kW/273 L PS), Removal and Installation).
If the engine still overheats, INSTALL a new radiator. REFER to: Radiator (303-03A Engine Cooling - 2.3 L EcoBoost (201 kW/273 L PS), Removal and Installation).
PINPOINT TEST C: ENGINE DOES NOT REACH NORMAL OPERATING TEMPERATURE

Normal Operation and Fault Symptoms

The engine cooling system maintains engine temperature during operation. Correct coolant flow through the engine, radiator and the remainder of the cooling system passages and components is important to maintain correct engine temperature.

Engine coolant flows mainly from the engine to the radiator circuit and back to the coolant pump. Coolant is sent from the coolant pump through the cylinder block and cylinder head. A separate circuit from the engine also supplies the heater core with coolant. The coolant pump circulates the coolant. The thermostat is a coolant temperature-actuated control valve. When the thermostat is closed, coolant flow bypasses the radiator circuit and returns to the coolant pump. When the thermostat is open, coolant flows through the radiator circuit to transfer engine heat to the outside air.

A concern that the engine does not reach normal operating temperature usually occurs when coolant flow through some coolant circuits (radiator, heater core) is greater than expected for the conditions. Heat is not allowed to build up in the engine because the heat exchanger removes too much heat, including the radiator, heater core and oil cooler. In addition, a suspected concern that the engine does not reach normal operating temperature may be related to low coolant level or air trapped in the system, which prevents hot coolant from reaching the heater core, a malfunctioning climate control system, or a concern perceived or related to an incorrect engine temperature sensor reading.

DTC Fault Trigger Conditions

Trouble Code Description Fault Trigger Condition
PCM P0125:00 Insufficient Engine Coolant Temperature for Closed Loop Fuel Control Set in the PCM when the CHT sensor does not reach the required temperature to enter closed loop operating conditions within a specified time after engine start.
PCM P0128:00 Thermostat Engine Coolant Temperature Below Thermostat Regulating Temperature Set in the PCM when the thermostat monitor does not reach the required engine operating temperature within a specified time after engine start.

Possible Sources

  • Low coolant level
  • Thermostat
  • Temperature Gauge
  • CKP
WARNING: Always allow the engine to cool before opening the cooling system. Do not remove the coolant pressure relief cap while the engine is running or the cooling system is hot. The cooling system is under pressure; steam and hot coolant can be expelled forcefully when the cap is loosened. Failure to follow these instructions may result in serious injury.
C1 PERFORM INSPECTION AND CHECKS
  • Complete the inspection and verification procedure described in this section.

Were any concerns found?
Yes REPAIR as necessary.
No GO to C2
C2 CHECK FOR DTC P0125 OR P0128
  • Using a scan tool, perform the PCM self-test.

Is DTC P0125 or P0128 present?
Yes GO to C3
No Cooling system operates normally. If a malfunctioning temperature sensor is suspected, CHECK the operation of the temperature sensor.
REFER to: Instrument Cluster, Message Center and Warning Chimes (413-01 Instrument Cluster, Message Center and Warning Chimes, Diagnosis and Testing).
If a climate control system malfunction is suspected, CHECK the operation of the climate control system. REFER to: Climate Control System (412-00 Climate Control System - General Information, Diagnosis and Testing).
If any other diagnostic trouble codes (DTCs) are present, REFER to: Engine Control Modules (303-14C Engine Control Modules - 3.3 L Duratec-V6/3.3 L Duratec-V6 - Hybrid (BP), Diagnosis and Testing).
C3 CHECK THE COOLANT LEVEL
  • Visually check the engine coolant level in the coolant recovery reservoir.

Is the engine coolant level within specification?
Yes INSTALL a new thermostat.
REFER TO: Thermostat (303-03A Engine Cooling - 2.3 L EcoBoost (201 kW/273 L hp), Removal and Installation).
CLEAR the Diagnostic Trouble Codes (DTCs). If the DTC returns, check the CHT sensor for proper operation.
No GO to Pinpoint Test A

Component Tests

Cooling System Pressure Test

  1. TURN the engine OFF.
  2. Check the engine coolant level and adjust as necessary.
  3. Connect the pressure tester to the degas bottle cap and the overflow hose. Install the pressure pump to the quick-connect fitting. Install the test adapter.

  1. NOTICE: Do not increase the cooling system pressure above the maximum pressure specified in the Specifications table in this section, or the cooling system components may be damaged.

    Slowly pump the pressure tester plunger until the gauge reading stops increasing and note the maximum pressure reading obtained. If the pressure reading exceeds the radiator cap maximum pressure specified in the Specifications table, install a new pressure relief cap.
  2. If the system does not hold pressure, remove the pressure relief cap and rinse it in clean water to remove all foreign material from the gasket. Inspect the sealing surface of the degas bottle filler neck for scratches or cuts. Install the pressure relief cap.
  3. Build pressure in the engine cooling system as described in Step 4 above. Observe the gauge reading for approximately 2 minutes. The pressure must not drop during this time. If the pressure drops within this time, inspect for leaks and repair as necessary.
  4. If no leaks are found after installing a new pressure relief cap, and the pressure drops, the leak may be internal to the engine. Check the coolant for engine oil and the engine oil for coolant.
    REFER TO: Engine (303-00 Engine System - General Information, Diagnosis and Testing).
  5. Release the system pressure by slowly loosening the pressure relief cap. Check the coolant level and adjust as necessary.

Thermostat

Install a new thermostat only after performing at least one of the following tests and inspections:

  • Precise Test B or C
  • Visual Inspection of the Thermostat

Visual Inspection of the Thermostat

  1. Remove the thermostat.
  2. Inspect the thermostat for signs of damage, including:
  • Valve not fully seated (light visible through the valve)
  • Foreign object lodged in the main valve
  • Bent or broken frame or flange
  • Bent or broken spring
  • Wax leakage from the wax element or a bulge in the element
  • Any other damage or distortion
  1. If damage is found during the inspection, remove all foreign objects or debris and install a new thermostat.

Radiator Leak Test, Removed from the Vehicle

NOTICE: Never leak test an aluminum radiator in the same tank of water in which copper/brass radiators are tested. Fluxes and caustic cleaners may be present in the tank and will damage the aluminum radiator.

  1. Check the radiator for leaks by submerging it in clean water and applying air pressure up to the maximum value specified in the Specifications table.

Test yourself

A quick Ford Explorer quiz: every answer comes with an explanation and a link to the manual page.