Ford 2003 Mustang Workshop Manual page 3087

Section 412-02
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 BT-7422-B and adapter
BT-7422-A from the radiator/heater core pressure tester in the heater water hose ends. Secure
the heater water hoses, plug and adapter with hose clamps.
5. Attach the pump and gauge assembly from the radiator/heater core pressure tester to the
adapter.
6. Close the bleed valve at the base of the gauge. 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, remove the heater core from the vehicle and carry out the
bench test.
Heater Core—Bench Test
1. Remove the heater core from the vehicle. For additional information, refer to
2. Drain all of the coolant from the heater core.
3. Connect the 101 mm (4 inch) test heater water hoses with plug and adapter to the core tubes.
Then connect the 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, install a new heater core.
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Section 412-02 .