Heater Core - Leakage Diagnostic Tips
Article No. 85-8-2HEATER CORE - LEAK - DIAGNOSTIC TIPS
FORD ALL
LINCOLN-MERCURY ALL
LIGHT TRUCK ALL
Good heater cores are being returned through the parts return system coded as leaking. Complaints of leaking may be caused by an inadequate seal between the heater hose and the heater core tubes allowing coolant to follow the tube to the heater core, leak into the passenger compartment and appear as a leaking heater core.
When diagnosing a suspect heater core leak, inspect the hose to heater core tube attachment to assure the connection is not leaking. If a leaking connection is found, correct the leak. If the connection appears not to be leaking, leak test the heater core before removing it from the vehicle using the following procedure:
HEATER CORE LEAK TEST
Pressure Test
1. Drain the coolant from the cooling system.
2. Disconnect the heater hoses from the heater core tubes.
3. Install a short piece of heater hose (approximately 4 inches long) on each heater core tube.
Figure 1:
4. Fill the heater core and hoses with water and install plug BT-7422-B and adapter BT-7422-A from Rotunda model 021-00012 or equivalent in the hose ends (Figure 1). Secure the hoses, plug and adapter with hose clamps.
Figure 2:
Figure 3 - TOOL 021-00012 WITH HEATER HOSE AND CLAMPS:
5. Attach the pump and gauge assembly Rotunda model 021-00012 or equivalent to the adapter (Figure 2). Close the bleed valve at the base of the gauge and pump 30 psi of air pressure into the heater core (Figure 3).
6. Observe the pressure gauge for a minimum of three minutes. The pressure should not drop.
7. If the pressure does not drop, no leaks are indicated.
8. If the pressure drops, check the hose connections to the core tubes for leaks. If the hoses do not leak, remove the heater core from the vehicle and perform the bench test.
Bench Test
1. Drain all coolant from the heater core.
Figure 4 - HEATER CORE BENCH TEST:
2. Connect the 4-inch test hoses with plug and adapter to the core tubes. Then connect the air pump and gauge assembly to the adapter (Figure 4).
3. Apply 30 psi of air pressure to the heater core with Rotunda model 021-00012 or equivalent, and submerge the core in water.
4. If a leak is observed, service or replace the heater core as necessary.
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