Heater Core: Testing and Inspection

Plugged Heater Core

Check to make sure the engine coolant is at the proper level, then start the engine and let it run until it is warmed to operating temperature. Turn on the heater, feel the inlet and outlet heater water hose connected to the heater core. If the inlet heater water hose is hot and outlet heater water hose is cooler, the heater core may be plugged.

Leak Test

SPECIAL SERVICE TOOL(S) REOUIRED







1. Inspect for visible evidence of coolant leakage at the heater water hose to heater core. A coolant leak at the heater water hose could follow the tube on the heater core and appear as a leak in the heater core.

2. For front heater core, remove the heater water hoses at the heater core using Heater Hose Disconnect Tool T85T-18539-AH.

3. Check for damaged or missing 0-rings. Replace if necessary and install heater water hoses by pushing heater water hose on tube until connector snaps in place over white heater hose quick connect couplings. Check tubes for damage. If damaged, replace heater core. Install heater water hoses.

4. For auxiliary core, check the system for loose heater hose clamps. The clamps should be tightened to 2-3 N.m (18-27 lb-in). If clamps are tight and leakage is found, check the heater core tubes for distortion. Severe distortion of the tubes could cause leakage at the hose connection. Replace heater core if necessary. Install heater water hoses.


Pressure Test

1. Drain the coolant from the cooling system.

2. Disconnect the heater water hoses from the heater core.

3. Install a short piece of heater water hose (approximately 4 inches long) on each 19.05 mm (3/4-inch) heater core coupling. Connect couplings to heater core.

4. Fill the heater core and heater water hoses with water and install Plug BT-7422-B and Adapter BT-7422-A from Rotunda Radiator/Heater Core Pressure Tester 021-00012 or equivalent in the ends. Secure the heater water hoses, plug and adapter with hose clamps.

5. Attach the Rotunda Radiator / Heater Core Pressure Tester 021-00012 or equivalent to the adapter. Close the bleed valve at the base of the gauge and pump 206kPa (30 psi) of air pressure into the heater core.

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. NOTE: Severe distortion of the core tubes could cause leakage at the coupling connection; repair or replace as necessary.









If the pressure drops, check the coupling or hose connections to the core tubes for leaks. If the couplings or heater water hoses do not leak, remove the heater core from the vehicle and bench test the heater core.

Bench Test

1. Drain all coolant from the heater core.

2. Connect the four-inch test heater water hoses with plug and adapter to the core tubes. Then connect the Radiator/Heater Core Pressure Tester 021-00012 or equivalent to the adapter.

3. Apply 206 kPa (30 psi) of air pressure to the heater core with Radiator/Heater Core Pressure Tester 021-00012 or equivalent and submerge the heater core in water.

4. If a leak is observed, repair or replace the heater core as necessary.