Heater Core Leak Check

WARNING: This page is about a different car, the 2019 Lincoln MKC. However, it is still accessible from the selected car via links, so may be relevant.

For information on Ford Color Coded Illustrations, refer to OEM COLOR CODING

Inspection

NOTE: A coolant leak in the heater hose could follow the heater core tube to the heater core and appear as a leak in the heater core.

Inspect for evidence of coolant leakage at the heater hose to heater core attachments.
NOTE: Spring-type clamps are installed as original equipment. Installation and overtightening of nonspecified clamps can cause leakage at the heater hose connection and damage the heater core.

Check the integrity of the heater hose clamps.
Drain the coolant from the cooling system. Refer to ENGINE COOLING SYSTEM DRAINING, VACUUM FILLING AND BLEEDING - 2.0L or ENGINE COOLING SYSTEM DRAINING, VACUUM FILLING AND BLEEDING - 2.3L
Disconnect the heater hoses from the heater core.
Install a short piece of heater hose, approximately 101 mm (4 in) long on each heater core tube.
Fill the heater core and heater hoses with water and install the plug (221373) and the adapter (221374) from the Pressure Test Kit. Secure the heater hoses, plug and adapter with hose clamps.

Courtesy of FORD MOTOR COMPANY
Attach the pump and gauge assembly from the Pressure Test Kit to the adapter.
- 014-R1072 Radiator Pressure Test Set
Courtesy of FORD MOTOR COMPANY
Close the bleed valve at the base of the gauge. Pump 138 kPa (20 psi) of air pressure into the heater core.
Observe the pressure gauge for a minimum of 3 minutes.
If the pressure drops, check the heater hose connections to the heater core tubes for leaks. If the heater hoses do not leak, replace the heater core.