Heater Core

Heater Core
1. Look for evidence of coolant leakage at the hose-to-heater core attachments.
2. Check the system for loose heater water hose clamps.
3. If a leak is found and the heater water hose clamps are tight, check the heater core tubes for distortion or evidence of being bent out of shape. Severe distortion of the heater core tubes could cause leakage at the heater water hose connection.

Plugged Heater Core
Ensure the engine coolant is at the proper level, then start the engine and feel the outlet heater water hose to see if it is hot. If it is not warm, flow through the heater core is restricted.

Pressure Test
Heater core leaks can be indicated by wet carpeting and coolant odor in the passenger compartment.

An inadequate seal between the heater core tubes can allow coolant to follow the tube to the heater core and appear as a leak. If a heater core leak is suspected, use the following procedures.

In-Vehicle Tests
1. Drain the coolant from the cooling system.
2. Disconnect the heater water hoses from the heater core tubes.
3. Install a short piece of heater water hose approximately 100 mm (4 inches) in length on each heater core tube.
4. Prepare the heater core as follows:
a.Fill the heater core and heater water hoses with water.






b. Install Plug BT-742 2-B in one heater water hose end and Adapter BT-742 2-A from Rotunda Radiator/Heater Core Pressure Tester 021-00012 or equivalent in the other heater water hose end.
c. Secure the hoses, plug, and adapter with hose clamps.
5. Pressure test the heater core as follows:
a. Attach the Rotunda Radiator/Heater Core Pressure Tester 021-00012 or equivalent to Adapter BT-742 2-A on the heater water hose.
b. Close the bleed valve at the base of the gauge.
c. Pump 103 kPa (15 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, the heater core does not leak.
8. If the pressure drops, check the heater water hose connections to the heater core tubes for leaks. If the heater water hoses do not leak, remove the heater core from the vehicle and perform the bench pressure test.

Bench Test
1. Drain all coolant from the heater core.
2. Attach the heater water hoses with the plug and adapter to the heater core tubes as indicated in the in-vehicle pressure test.






3. Attach the Rotunda Radiator / Heater Core Pressure Tester 021-00012 or equivalent to the adapter.
4. Pump 103 kPa (15 psi) of air pressure into the heater core.
5. Submerge the heater core in water.
6. If a leak is observed, service or replace the heater core.