How To Flush A Heater Core? 3 Easy Ways!

Are you wondering how to flush a heater core? Follow the steps to attach the pressure source, drain the coolant and grime, and prepare as you wash the heater core. These are necessary to follow, mainly if the vehicle heater does not work as it used, or it stops working in its entirety.

Maybe it’s the clogging of the heater core. As per the heater core, it is the same as the radiator, once a part of the coolant system. The hot coolant that passes through engine parts runs through a heater core, while air forces past it that continue to the vehicle’s cabin.

How to flush a heater core

Clogging in the heater core prevents the coolant, and limits the quantity of heat transferred. The flushing of the heater core removes the clogs; however, replacing the heater core is essential when it does not work correctly as this is just an overview, so read on further!


Ways To Flush The Heater Core

Below is the practical guide to follow when you flush the heater core.


#1. Attaching the source of pressure

Locate the heater core first through a vehicle’s firewall, where inlet and outlet pipes are located in the firewall that separates the engine of the vehicle’s cabin. The location differs from one vehicle to another; you find it challenging to locate the hoses; read the service manual for a specific vehicle. In this regard, there are two nozzles, one in the coolant that flows in and out that flows out. Try to search for the nozzles as you follow the coolant hoses in a coolant system.

Next to consider is to get the heater hoses disconnected with coolant hoses attaché to hose clamps, but loosen them first with a wrench or screwdriver. Get the heater hoses disconnected while water and coolant pour, so place the container directly underneath the car’s hoses. The hose clamp damaged due to loosening requires the purchase of replacement clamps at the nearest auto parts store. Be wary of avoiding spilling coolant, since it’s not suitable for the environment.

Position the hose facing the container and force the water or air in the system, to help clean the blocked heater core. The system’s water, grime, and coolant are expelled from the inlet hose. Position the hose so that things will pour into the container.

Then, insert the water hose or airline through an outlet hose that uses the airline for the air compressor. If it’s not possible, use the airline when pushing out the rest of the grime and coolant in a heater core. Use a garden hose for this purpose and place the hose or the airline in an outlet hose of the heater core. When flushing the system, use water to hose; however, compressed air moves more challengingly when breaking blockages. 

Seal the line where the airline or hose gets connected to a hose outlet. Wrap the area using a silicone coupler or duct tape, thus, creating a seal. The pressure leaks back out of the hose due to severe line blockage but does not penetrate the clog. The excellent seal in a hose pushes water or air into the system and forces the pressure through a clog.


#2. Draining the coolant and grime

Turn the air compressor or hose on to seal the hose or airline, including the hose outlet, and turn the water or air. Enable the pressure as it builds in the system and removes the clogs. The grime and coolant drain out of a heater inlet and through the container underneath the vehicle. Leave the airline or hose running for several minutes to ensure pressurization of the system.

Afterward, allow the grime and coolant to drain and turn off a water hose or airline, allowing the fluids to drain to completely drain a container underneath the vehicle. Ensure the container won’t overflow if you use a hose. The system continues to drain for several minutes after turning off the water or airflow.

When removing the blockage, do the same procedure with a water hose that switches some hoses. Fill the system using water and drain it to best remove the lousy coolant. Pour your container into a sealable container and separate the container between those flushes, ensuring it does not overflow. Afterward, flush the heater core once or twice before you move on. Reconnect the outlet and inlet hoses and place them back in the nozzles. Secure them using hose clamps that reseal the system best and refill it.

Securely fasten its hose clamps, or the water pressure pushes hoses from coming off. Replace any rusty or damaged hose clamps before you reinstall the stockings; they reach a single nozzle. It’s likewise easier determining what one goes to. Refill its coolant system as you open its radiator cap to refill its coolant system. Pour in a 50/50 mixture of coolant and water and use the suitable coolant for a vehicle. Fill it and screw the cap to its place. You may also be interested to know about the symptoms of a clogged heater core.


#3. Flushing the heater core

So, how to flush a heater core? Please park your car on the ground and never jack it up on its slanted surface. When centralized underneath the jack, look for a level or firm texture to support the vehicle’s front part. Concrete and blacktop are always suitable surfaces on where you jack the car. Avoid jacking up a car on dirt, gravel, and grass. Enable the engine as it cools up completely. Jack the car up as you slide the scissor or trolley underneath the vehicle.

Lift to lower a trolley jack or handle and turn, so you jack the car up. Finally, place the container underneath the car catching up some drained fluids. Flush the grime and coolant out of a heater and a part of a coolant system. Read the service manual and know the coolant capacity, and choose a container that does not leak.


It’s A Wrap!

Now you learn how to flush a heater core with the three detailed steps mentioned. Be very careful when you follow each of the steps. Also, the heater core is similar to the radiator that was once a part of the system. It also matters to read the service manual and learn more about its coolant capacity. You may also want to read about how much to replace a heater core and how to bypass heater core.

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