How do you burp a Subaru cooling system?
Burping a Subaru cooling system is an important maintenance task that helps remove air pockets and ensure proper coolant circulation. This process helps prevent overheating and ensures your Subaru's engine runs at optimal temperature. Here's a step-by-step guide on how to burp a Subaru cooling system.
Why Burping the Cooling System is Important
Air pockets can form in a Subaru's cooling system for various reasons, such as during a coolant change, a system repair, or even normal operation. These air pockets can prevent proper coolant circulation, leading to hot spots and potential engine damage. Burping the system helps remove these air pockets and ensures the coolant flows freely throughout the system. This helps maintain optimal engine operating temperatures and prevents overheating issues.
Steps to Burp a Subaru Cooling System
- Make sure the engine is completely cooled down before starting.
- Locate the radiator cap and slowly unscrew it, allowing any built-up pressure to release.
- Start the engine and let it run at a moderate RPM for 5-10 minutes.
- Observe the coolant level in the radiator. If it drops, add more coolant to bring it up to the proper level.
- Repeat steps 3-4 until the coolant level remains stable and no more air bubbles are visible.
- Once the system is fully burped, replace the radiator cap and ensure it is tightened securely.
By following these steps, you can effectively burp your Subaru's cooling system and ensure proper coolant circulation. This maintenance task should be performed periodically, especially after any work on the cooling system or after a coolant change.
How to burp a Subaru coolant system?
Run heat on low setting, raise up front of car, idle/Rev 2-3k, run until she steams. After steaming wait for rad fans to kick on. By then all air should be removed from system. A burp funnel helps a Lot, but isn't needed.
How do you get air out of a Subaru cooling system?
Rev the engine between 2500 to 4000 rpm off and on for 5 minutes, this should allow the water pump to force air out of the system.
How to burp air out of a cooling system?
To burp a coolant system, ensure the engine is cool, then fill the overflow reservoir or radiator with coolant. Start the engine, turn the heater to the highest setting, and let it run until it reaches operating temperature to allow trapped air to escape. You can help force air out by gently squeezing the radiator hoses, and for a more effective process, place a no-spill funnel in the radiator to catch air bubbles and use a spill-free funnel kit with an adapter for the radiator cap.
Steps to burp the coolant system
- Cool the engine: Make sure the engine is cool before you begin. Do not remove the radiator cap when the engine is hot.
- Fill the system: Fill the coolant reservoir or radiator with the correct type of coolant. If the system is completely drained, you may need a no-spill funnel kit, which seals to the radiator to help you manage the coolant and capture air bubbles.
- Start the engine: Start the car and turn the heat on to its highest setting. This opens the heater core, allowing it to be purged of air as well.
- Work out the air: Let the engine run until it reaches operating temperature. As the engine warms up, the thermostat will open, and you will see air bubbles rise to the top and exit the system. You can help dislodge air bubbles by gently squeezing the upper and lower radiator hoses. Revving the engine can also speed up this process.
- Monitor the coolant level: Keep an eye on the coolant level in the funnel or reservoir and add more as needed to keep it full, preventing more air from being sucked in. The coolant level will likely drop as the thermostat opens and the system circulates coolant.
- Top off and re-check: Once the bubbles stop coming out and the fans cycle on and off a couple of times, turn off the engine. Top off the overflow reservoir with coolant after the engine has cooled down. Check the coolant level again after a day or two of driving, as some air may still be trapped.
How do I get trapped air out of my cooling system?
To get air out of a coolant system, raise the front of the car, turn the heater to its highest setting, and then slowly fill the radiator with coolant while the engine is running. Allow the engine to reach operating temperature to open the thermostat and circulate the coolant, which will help push out trapped air bubbles. You can also squeeze the radiator hoses to help dislodge air pockets and continue to top off the coolant as needed until no more bubbles emerge.
Step 1: Prepare the car
- Park the car on an incline or use a jack to raise the front end to help air move towards the highest point (the radiator cap).
- Turn the vehicle's heater to the highest temperature and fan speed.
- Remove the radiator cap slowly and attach a funnel to the radiator neck to prevent spills.
- Begin to add coolant to the funnel, but don't fill it completely yet.
This video demonstrates how to prepare your car and a funnel for bleeding the cooling system: 58sGearheadbryanYouTube · Mar 23, 2025
Step 2: Bleed the system
- Start the engine and let it idle.
- As the engine warms up, the thermostat will open, and the coolant will begin to circulate, pushing air out through the funnel.
- Monitor the funnel and top it off with coolant as the level drops, keeping the funnel from emptying completely.
- Gently squeeze the upper and lower radiator hoses to help dislodge trapped air bubbles.
- Once no more air bubbles are seen coming out of the funnel, and the heater is blowing hot air, the system is likely bled.
This video shows the process of bleeding air from the cooling system while the engine is running: 57sChrys GainesYouTube · Feb 2, 2023
Step 3: Finish the process
- With the engine still running, carefully remove the funnel, using a rag or a plug to prevent spills.
- Top off the coolant in the overflow reservoir to the "full" line if necessary.
- Turn off the engine and let it cool down before fully replacing the radiator cap.
- After the engine has completely cooled, check the coolant level one last time and top it off if needed.
