How Do You Change a Heater Core?


Changing a heater core is usually a complicated job.  Even on older vehicles, it is often difficult just to gain access to and remove the old heater core.

What is a car heater core?

The heater core is essentially a radiator.  Coolant gets pushed through it by your water pump, just like the radiator on the front of your vehicle, but the heater core is usually located somewhere under your dashboard.  Your vehicle’s ventilation system fan pushes air through the heater core and into the cabin of your car or truck to heat it.  The heater core is connected to your engine’s cooling system usually by two hoses that pass through your firewall, often on the passenger side.

The heater core is usually made of thin copper or aluminum so it can easily transfer heat from the coolant to the cabin air for heating, but this also make it easily susceptible to cracks, breaks and holes.

How do you change a car heater core?

Replacing a heater core usually involves the removal of a significant amount of interior paneling and duct work.  It can be difficult to do yourself, or it can be very expensive to pay a mechanic to do given the large amount of time required to remove the necessary components to gain access to the heater core.  Simply allowing your heater core to continue to leak is a poor option as it will allow hot engine coolant to flow into the cabin of your vehicle.  This can cause unpleasant odors, wet carpets and possibly danger to your passengers because of the high temperatures.  Also, as more coolant leaks out, you risk overheating your engine.

The most effective way to stop a leaking heater core is to use BlueDevil Head Gasket Sealer or Pour-N-Go.  BlueDevil Pour-N-Go is a quick and easy solution to many cooling system leaks in your car or truck, including a leaking heater core.  BlueDevil Pour-N-Go is an easy to use product that you simply add to your engine coolant and will work to seal your leak as you drive.  For larger leaks, or vehicles with large cooling systems, use BlueDevil Head Gasket Sealer after a complete system flush with BlueDevil Radiator Flush.


BlueDevil Products can be found on or at AutoZone, Advance Auto Parts, O’Reilly Auto Parts, NAPA, and other major auto parts retailers.

7 responses to "How Do You Change a Heater Core?"


  1. Tefo on July 5, 2017 at 12:27 am

    Were to pour the BlueDevil Pour N-G in my car to seal the heat core.Caue as I’m reading I found that I have the same problem

    • BlueDevil Pro on July 5, 2017 at 11:15 am


      The BlueDevil Pour-N-Go Head Gasket sealer is added through the radiator cap and would be able to seal a heater core leak. Feel free to contact our technical support line at 888-863-0426 with any other questions.

      Thank you!


      • Steve on September 11, 2017 at 2:33 pm

        What does it do to the radiator and water pump ? I have a motorhome with a diesel, and heater core leaking , how much do I use ?

        • BlueDevil Pro on September 12, 2017 at 9:22 am


          For a leaking heater core, we recommend using the BlueDevil Head Gasket Sealer ( The product does not contain any solid or particulate matter, so it is a non-clogging product. There is a cooling system capacity table on the back of the bottle (below the directions) that would show you how much of the product to use per your cooling system capacity. Feel free to contact our technical support line at 888-863-0426 with any other questions.

          Thank you!


  2. Nancy on November 30, 2019 at 8:42 pm

    Does this also work for a clogged heater core.

    • BlueDevil Pro on December 2, 2019 at 9:57 am


      If your heater core is clogged, you may want to attempt flushing the heater core prior to having it replaced. If you bring the vehicle to a shop with a flushing machine, they would be able to back flush the heater core, hopefully removing whatever is restricting/clogging.

      Thank you!


  3. Roy on March 22, 2024 at 11:56 pm

    What tools do I need to remove an old heater core on a 98 Buick LeSabre 3.8 l engine

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