How to Replace the Heater Core

by Hank MacLeod

The heater core in your car or truck is crucial on cold winter days to provide heat inside your vehicle. When it breaks down, not only do you not have heat but engine coolant can leak into the vehicle's interior. The replacement process can be expensive because of the amount of time it takes to dismantle the dashboard to get to the core. The heater core's location can vary by vehicle; obtaining a manufacturer's repair manual is recommended.

Pop the hood and disconnect the negative (black) battery terminal. Refer to the manufacturer's repair manual to locate the heater core. Follow directions on how to remove the dashboard and other obstructive parts. Place the appropriate socket or wrench on the heater core mount bolts and remove them.

Place plastic sheets underneath the heater core and connected hoses as coolant will drain out. Pull off the hoses attached to the heater core, taking note of their locations. You may have to first unscrew or squeeze off the hose couplings.

Pull out the heater core, taking care not to dump its contents. Compare it to the new heater core, carefully bending any hoses to match the old ones to avoid later problems. Note any new mounting parts that come with the heater core and replace the old parts.

Inspect the intake/outtake hoses carefully for signs of cracks or rot. Replace them if necessary. Reverse the removal instructions to correctly install the new heater core.

Wrap up the protective plastic carefully and dispose of it per local law. Replace all the parts you removed to get to the heater core.

Open the radiator cap and overflow tank and replace any lost coolant with fresh 50/50 mix. Reconnect the negative battery terminal. Start the car and follow proper guidelines for coolant replacement per the repair manual. Allow the vehicle to reach operating temperature and be sure the heat works properly.


  • check This may be a good time to flush your coolant and check your hoses, since a main component of your cooling system is being replaced.


  • close Make certain your engine is cold, as hot coolant can cause injury.
  • close Coolant is toxic; keep children and pets away from it.

Items you will need

About the Author

Residing in Pontiac, Mich., Hank MacLeod began writing professionally in 2010. He writes for various websites, tutors students of all levels and has experience in open-source software development. MacLeod is pursuing a Bachelor of Science in mathematics at Oakland University.

Photo Credits

  • photo_camera tools image by AGITA LEIMANE from