Lincoln Navigator: Engine Cooling - 3.5L EcoBoost (272kW/370PS) / Engine Cooling. Diagnosis and Testing

• Wiring
• Relays
• Fuses
• Cooling fan motor

• Wiring
• Relays

Normal Operation and Fault Conditions

The engine cooling system is a closed system providing for coolant expansion and contraction as well as changes in pressure as coolant warms and cools with engine operation. Various gaskets, seals, hoses and clamps contain coolant within the cooling system and keep other fluids and contaminants from entering the cooling system.

Possible Sources

• Coolant hoses or tubes
• Hose clamps
• Thermostat O-ring seal or gasket
• Coolant pump O-ring seal or gasket
• Thermostat housing
• Oil cooler (may leak internally or externally)
• Transmission fluid cooler (may leak internally or externally)
• EGR cooler (may leak internally or externally)
• Transmission fluid heater coolant control valve
• Pressure relief cap
• Coolant pump leaking from weep hole
• Cabin heater coolant pump
• Heater core
• Coolant inlet connector
• Engine gaskets (may leak internally or externally)
• Degas bottle
• Cylinder block core plugs
• Cylinder head core plugs
• Block heater (if equipped)
• Turbocharger

  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.

• Visually inspect the possible sources for obvious signs of physical damage or failure.

NOTE: Allow the engine to cool before checking the engine coolant level.

• Ignition OFF

• Visually inspect the engine coolant level at the degas bottle and adjust as necessary. Pressure test the engine cooling system. Refer to Component Tests, Cooling System Pressure Test in this section.

• Inspect the engine coolant in the degas bottle for signs of engine oil.

• Remove the oil level indicator from the engine.

• Check the engine coolant in the degas bottle for signs of transmission fluid.

• Remove the transmission oil leveling plug.

• Check the transmission fluid for engine coolant.

NOTE: Use UView® Combustion Leak Tester part number UVU560000-R or equivalent.

• Using a cooling system combustion gas leak tester, following the instructions supplied with the tester, check the coolant for combustion gases.

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 head. A separate circuit from the engine also feeds the heater core with coolant. The coolant pump circulates the coolant. 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.

DTC Fault Trigger Conditions

Possible Sources

• Low coolant level
• External engine coolant leak
• Airlock in system
• Pressure relief cap installation
• Restricted airflow through A/C condenser/radiator
• Internal engine coolant leak
• Coolant condition/concentration
• Turbochargers
• Non-OEM engine enhancement components
• Cooling fan
• Cooling fan clutch
• CHT sensor
• ECT sensor
• Radiator
• Thermostat
• Coolant pump
• Coolant flow restriction
• Active grill shutter assembly

• Visually inspect the possible sources for obvious signs of physical damage or failure.

• Ignition ON.

• Using a scan tool, perform PCM self-test.

• Review the PCM DTCs.

NOTE: Verify no vehicle front end damage is present.

• Check the radiator or A/C condenser for an external obstruction such as leaves or cardboard and verify all air deflectors are present.

• Ignition OFF.

• Visually check the engine coolant level in the coolant expansion tank and adjust as necessary. Pressure test the cooling system.

• Inspect the engine coolant in the coolant expansion tank for signs of engine oil.

• Remove the oil level indicator from the engine.

• Check the engine coolant in the degas bottle for signs of transmission fluid.

• Remove the transmission oil leveling plug.

• Check the transmission fluid for engine coolant.

NOTE: Use UView® Combustion Leak Tester part number UVU560000-R or equivalent.

• Using a cooling system combustion gas leak tester, following the instructions supplied with the tester, check the coolant for combustion gases.

• Check the coolant for dirt, rust or contamination and check the coolant concentration.

• Start the engine.

• Place the climate control function selector in the MAX A/C position and the blower motor switch in the HI position.

• Start the engine.

• Allow the engine to run for 30 minutes. Place the climate control function selector in the MAX HEAT position. Feel the heater outlet hose.

NOTE: This cooling system uses a cold side thermostat. The coolant in the radiator must reach full operating temperature for the thermostat to remain in an open state.

• Start the engine.

• Allow the engine to run for 30 minutes. Place the climate control function selector in the MAX HEAT position. Feel the lower radiator hose.

• Carry out the Thermostat Visual Inspection in the Component Tests portion of this section.

Normal Operation and Fault Conditions

The engine cooling system maintains 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 head. A separate circuit from the engine also feeds the heater core with coolant. The coolant pump circulates the coolant. 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 in order to transfer engine generated heat to the outside air.

Concerns of engine inability to reach normal operating temperature typically occur when the rate of coolant flow through some coolant circuits (radiator, heater core) is more than expected given the conditions. Heat is not allowed to build in the engine because a heat exchanger is removing too much heat, including the radiator, heater core and oil cooler. In addition, perceived concerns that the engine does not reach normal operating temperature can be related to a low coolant level or trapped air which does not allow for hot coolant to be available at the heater core, an inoperative climate control system, or for concerns perceived or related to an incorrect engine temperature gauge indication.

DTC Fault Trigger Conditions

Possible Sources

• Low coolant level
• Thermostat
• Temperature gauge
• CHT
• ECT sensor

  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.

• Visually inspect the possible sources for obvious signs of physical damage or failure.

• Using a scan tool, perform the PCM self-test.

NOTE: Allow the engine to cool before checking the coolant expansion tank.

• Visually check the engine coolant level in the coolant expansion tank