1. Drain the cooling system by opening the petcock on the bottom of the radiator. Once the coolant has drained, close the petcock.
2. Locate the heater core inlet and outlet hoses inside the engine compartment. Both hoses are usually located on the passenger side of the engine. Disconnect the hoses from the heater core.
3. Remove the nuts holding the heater core to the firewall inside the passenger compartment. There are usually two or three nuts on each side of the heater core.
4. Once the nuts are removed, carefully pull the heater core out of the firewall. Be careful not to damage the fins on the heater core.
5. Inspect the heater core for damage. If it is damaged, replace it with a new one.
6. To reinstall the heater core, reverse the steps listed above. Be sure to tighten the nuts securely so that the heater core does not leak.
7. Once the heater core is installed, refill the cooling system. Start the engine and let it run for a few minutes to check for leaks.
