If you decided to drain your coolant system and add more coolant, there's a chance you have air in the lines. The air in your line can cause major damage to your engine from overheating but it can also cause a loss of other functions like being able to heat the cab of your car or truck. Here we will explain how to bleed the coolant system to get the air out.

How to Bleed the Cooling System Properly on Most Vehicles

Reasons to Bleed the Cooling System

When you drain your coolant system or add fluid because it was low, you want to bleed the coolant system to prevent air in the engine block, radiator, radiator hoses, heater core, and several other engine components. Air in any of these components and cavities can cause major damage to your engine, coolant systems, or prevent proper operation of different systems within your vehicle.

How to Get Air Out of the Cooling System

Bleeding the Coolant System Steps

1. Radiator Cap Has to be Removed

Make sure the vehicle is cool before removing the radiator. If you remove the cap while the engine is hot you may be scalded by boiling liquid and no one wants that. I repeat, make sure the engine is cool. Then, remove the radiator cap.

2. Find a Long Mechanic’s Funnel

Insert the multipurpose funnel in the opening of the radiator.

3. Pour Coolant into the Radiator

Pour coolant into the radiator until it’s full; to the top. It can take a while to get there. The radiator will likely bubble and gurgle as it fills in some of the air bubbles that exist in the radiator.

4. Now Get in and Start the Vehicle

After filling the radiator and it stops draining, bubbling, and gurgling, start the vehicle.

5. Adjust the Heater Settings

Turn the heat to the highest setting and put the fan on low. Make sure the vents are open so you can feel the airflow. By doing this you can keep an eye on the temperature of the engine and the internal temperature of the heater. The radiator level should drop.

6. As the Radiator Level Drops, Keep Filling It.

You need to keep the radiator topped off while the engine is running. The coolant level will drop significantly as the engine heats up and the thermostat opens to start controlling the engine temperature.

7. Make Sure the Cab is Heating Up

Place your hands or face in front of the vents to make sure hot air is blowing from them. Your face may be more sensitive to the temperature change and is often more accurate than your hands.

8. What Does the Temperature Gauge Say?

Look at the temperature gauge on your car now and see where it is. If it’s in the normal range everything is working as it should, so far.

9. Shut Your Vehicle Off and Put The Cap Back On

Making sure the coolant level is full, you can now replace your radiator cap.

10. And Now We Test Drive It

Keep the vehicle running for a minute or two just to ensure it doesn’t overheat or start acting up. Once you’re sure everything is operating as it should, including your cab heat, take it for a 10-minute drive or so, keeping an eye on the gauges and the interior temperature. If everything seems fine, bring it home, park it, and let it cool down.

11. Check the Fluid Level Inside the Radiator Once the Cooling System Is Cool

Once your vehicle is again cool, open the radiator cap and make sure your radiator is still full. If it is the bleeding should have worked and you shouldn’t experience any of the issues we discussed earlier. If you notice your vehicle heat acting up or your engine overheating, you can start by repeating the steps above.

When your car's coolant system is acting, overheating, or not heating enough, Partshawk is your one-stop-shop for all of your car’s HVAC repair parts. From radiators and hoses to heater cores and reservoirs we have you covered. Contact us today if you have any questions or need help finding the parts you need to fix your car’s coolant system.