How to Get Air Out of Your LS Swap Cooling System The Right Way, by ICT Billet on YouTube. 4 min 52 s.
- Video length
- 4 min 52 s
- Time to do it
- 30 minutes
- Difficulty
- Easy
- Steps
- 9
What you need
Steps
Park the car on level ground and let the engine cool completely before you open anything. Hot coolant can spray out and burn you.
Open the radiator cap and the highest heater or coolant hose point in the system. Fill the radiator slowly with mixed coolant until the level sits at the neck.
Fill the coolant reservoir to its cold mark. Keep a funnel in the radiator neck so the level stays above the top while air works its way out.
Start the engine and turn the heater to full hot with the blower on low. This opens the heater core so trapped air can escape.
Let the engine idle and watch the radiator neck. Bubbles will rise and the coolant level will drop as air leaves. Top it up as it falls.
Squeeze the upper and lower radiator hoses a few times with a gloved hand. This pushes air pockets toward the cap opening.
Run the engine until the thermostat opens and the upper hose gets hot. Keep topping up until bubbles stop and the level holds steady.
Fit the cap and let the engine cool. Check the level again and top up the radiator and reservoir as needed.
Take a short drive with the heater on, then let it cool and recheck. Repeat the top up until the level stops dropping.
Tips and common mistakes
Never open the radiator cap on a hot engine, wait until it is cool to the touch.
Use a spill-free funnel that sits above the radiator neck so the coolant stays higher than the engine.
If the temperature still climbs, check for a stuck thermostat or a leaking head gasket before bleeding again.
Questions
How do I know all the air is out?
Bubbles stop rising at the radiator neck and the coolant level holds steady while the engine idles with the heater on hot.
Can I bleed the system without running the engine?
Not fully. The thermostat and water pump need the engine running to push air out of the block and heater core.
Why does my LS still overheat after bleeding?
A stuck thermostat, a bad cap or a head gasket leak can mimic trapped air. Pressure test the system if the level keeps dropping.
This guide was drafted from the video's details and general task knowledge. It has not been checked against the full video. Check the video and relevant product instructions before following a procedure. Report a correction.
