Expedition 4WD V8-4.6L SOHC VIN 6 (1997)
and damage the heater core.
PLUGGED HEATER CORE
WARNING: THE HEATER CORE INLET HOSE WILL BECOME TOO HOT TO HANDLE IF THE SYSTEM IS WORKING
CORRECTLY.
Check to see that the engine coolant is at the proper level. Start the engine and turn on the heater. When the engine coolant reaches operating
temperature, feel the heater core outlet hose to see if it is hot. If it is not hot, the heater core may have an air pocket or may be plugged, or the
thermostat is not working properly.
Pressure Test
Use Radiator/Heater Core Pressure Tester to perform the pressure test.
1. Drain the coolant from the cooling system.
NOTE: Due to space limitations, a bench test may be necessary for pressure testing.
2. Disconnect the heater water hoses from the heater core.
3. Install a short piece of heater water hose, approximately 101 mm (4 inches) long on each heater core tube.
4. Fill the heater core and heater water hoses with water and install plug and adapter from Radiator/Heater Core Pressure Tester in the heater
water hose ends. Secure the heater water hoses, plug and adapter with hose clamps tightened to specification.
5. Attach the pump and gauge assembly from Radiator/Heater Core Pressure Tester to the adapter.
6. Close the bleed valve at the base of the gauge and pump 241 kPa (35 psi) of air pressure into the heater core.
7. Observe the pressure gauge for a minimum of three minutes.
8. If the pressure drops, check the heater water hose connections to the core tubes for leaks. If the heater water hoses do not leak, test the heater
core as follows:
1. Drain all coolant from the heater core.
2. Remove the heater core from the A/C evaporator housing.
3. Connect the 101 mm (4 inches) test heater water hoses with plug and adapter to the core tubes. Then connect Radiator/Heater Core
Pressure Tester to the adapter.
4. Apply 241 kPa (35 psi) of air pressure to the heater core. Submerge the heater core in water.
5. If a leak is observed, service or replace the heater core.
