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Pinpoint Test B: The Engine Overheats

WARNING: This page is about a different car, the 2009 Ford Mustang. However, it is still accessible from the selected car via links, so may be relevant.
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. B1 CARRY OUT INSPECTION AND VERIFICATION 
    1. YES  : REPAIR as needed. TEST the system for normal operation.
    2. NO  : Go to  B2 .
  2. B2 CHECK FOR DTCs 
      NOTE: Refer to the Introduction - Gasoline Engines for correct scan tool hook-up procedure.
    • Check for DTC P0217, P1285 or P1299.
    • Is DTC P0217, P1285 or P1299 present? 
    1. YES  : Go to  B3.
    2. NO  : Actual engine overheating has not been verified. CHECK the ECT gauge operation. REFER to INSTRUMENT CLUSTER (IC), MESSAGE CENTER, AND WARNING CHIMES . If any other DTCs are retrieved, REFER to the Introduction - Gasoline Engines .
  3. B3 CHECK FOR AN AIRFLOW OBSTRUCTION 
    • Check the radiator or A/C condenser for an external obstruction such as leaves or cardboard.
    • Is an obstruction present? 
    1. YES  : REMOVE the obstruction. TEST the system for normal operation.
    2. NO  : Go to  B4.
  4. B4 CHECK THE ENGINE COOLANT LEVEL 
    NOTE: Allow the engine to cool before checking the coolant level.
    • Key in OFF position.
    • Visually check the engine coolant level in the degas bottle or coolant expansion tank.
    • Is the engine coolant level within specification? 
    1. YES  : Go to  B5.
    2. NO  : ADJUST the engine coolant level as necessary. Go to  B5.
  5. B5 PRESSURE TEST THE ENGINE COOLING SYSTEM 
    • Pressure test the engine cooling system. Refer to Component Tests , Cooling System Pressure Test.
    • Does the engine cooling system leak? 
    1. YES  : REPAIR or INSTALL new components. TEST the system for normal operation.
    2. NO  : Vehicles equipped with an expansion tank, go to  B6. Vehicles equipped with a degas bottle, go to  B7.
  6. B6 CHECK THE PRESSURE RELIEF CAP 
    • Carry out the pressure relief cap pressure test. Refer to Component Tests , Pressure Relief Cap Pressure Test.
    • Is the pressure relief cap OK? 
    1. YES  : Go to  B7.
    2. NO  : INSTALL a new pressure relief cap. TEST the system for normal operation.
  7. B7 CHECK THE ENGINE COOLANT FOR AN INTERNAL LEAK 
    • Inspect the engine coolant in the degas bottle or coolant expansion tank for signs of engine oil or transmission fluid.
    • Is engine oil or transmission fluid evident in the coolant? 
    1. YES  : If engine oil is evident, go to ENGINE SYSTEM - GENERAL INFORMATION for engine diagnosis. If transmission fluid is evident, INSTALL a new radiator. REPAIR the transmission as necessary. Refer to the appropriate AUTOMATIC TRANSAXLE/TRANSMISSION - 5R55S for the procedure. TEST the system for normal operation.
    2. NO  : Go to  B8.
  8. B8 CHECK THE ENGINE OIL AND TRANSMISSION FLUID FOR COOLANT 
    • Remove the oil level indicators from the engine and the transmission.
    • Is coolant evident in the oil or transmission fluid? 
    1. YES  : If coolant is in the engine oil, go to ENGINE SYSTEM - GENERAL INFORMATION . If coolant is in the transmission fluid, INSTALL a new radiator. REPAIR the transmission as necessary. Refer to the appropriate AUTOMATIC TRANSAXLE/TRANSMISSION - 5R55S for the procedure.
    2. NO  : Go to  B9.
  9. B9 CHECK THE COOLING SYSTEM FOR COMBUSTION GASES 
      NOTE: Use U-View® Combustion Leak Tester part number 560000 or equivalent.
    • Using a cooling system combustion gas leak tester, following the instructions supplied with the tester, check the coolant for combustion gases.
    • Are combustion gases present? 
    1. YES  : Go to ENGINE SYSTEM - GENERAL INFORMATION for engine diagnosis.
    2. NO  : Go to  B10.
  10. B10 CHECK COOLANT CONDITION 
    • Check the coolant for dirt, rust or contamination and check the coolant concentration.
    • Is the coolant condition OK? 
    1. YES  : Vehicles equipped with an electric cooling fan, go to  B11 . Vehicles equipped with only a mechanical cooling fan, go to  B12 .
    2. NO  : FLUSH the engine cooling system. REFER to Cooling System Flushing . TEST the system for normal operation.
  11. B11 CHECK THE ELECTRIC COOLING FAN OPERATION 
    • Start the engine.
    • Place the climate control function selector in the MAX A/C position and the blower motor switch in the HI position.
    • Did the electric cooling fan operate? 
    1. YES  : If the vehicle is also equipped with a mechanical cooling fan, go to  B12 . Otherwise, go to  B13 .
    2. NO  : DIAGNOSE the electric cooling fan operation. REFER to Introduction - Gasoline Engines .
  12. B12 CHECK THE MECHANICAL COOLING FAN OPERATION 
    • Key in OFF position.
    • If the vehicle is equipped with a viscous fan clutch, carry out the Fan Clutch Tests in the Component Tests . If the vehicle is equipped with an electronically actuated fan clutch, refer to the Introduction - Gasoline Engines .
    • Is the cooling fan operation OK? 
    1. YES  : Go to  B13.
    2. NO  : INSTALL a new fan clutch. TEST the system for normal operation.
  13. B13 CHECK THE COOLANT PUMP OPERATION 
    • Start the engine.
    • Allow the engine to run for 10 minutes (hot side thermostat equipped vehicles) or 30 minutes (cold side thermostat equipped vehicles). Place the climate control function selector in the MAX HEAT position. Feel the heater outlet hose.
    • Is the heater outlet hose hot? 
    1. YES  : Go to  B14.
    2. NO  : INSTALL a new coolant pump. TEST the system for normal operation.
  14. B14 CHECK THE THERMOSTAT OPERATION 
    • Start the engine.
    • Allow the engine to run for 10 minutes (hot side thermostat equipped vehicles) or 30 minutes (cold side thermostat equipped vehicles). Feel the upper radiator hose (hot side thermostat equipped vehicles) or the lower radiator hose (cold side thermostat equipped vehicles).
    • Is the upper (hot side thermostat equipped vehicles) or lower (cold side equipped vehicles) radiator hose hot? 
    1. YES  : CHECK the engine coolant temperature gauge operation. REFER to INSTRUMENT CLUSTER (IC), MESSAGE CENTER, AND WARNING CHIMES .
    2. NO  : Go to  B15.
  15. B15 VISUALLY INSPECT THE THERMOSTAT 
    • Carry out the Thermostat Visual Inspection in the Component Tests .
    • Is the thermostat damaged? 
    1. YES  : INSTALL a new thermostat. TEST the system for normal operation.
    2. NO  : INSTALL a new thermostat. TEST the system for normal operation. If the engine still overheats, INSTALL a new radiator. TEST the system for normal operation.
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