How to bleed your BMW e46 cooling system the RIGHT way #bmw #cars #mechanic #3series #e46, by The Questionable Craftsman on YouTube. 1 min 20 s.
- Video length
- 1 min 20 s
- Time to do it
- 30 minutes
- Difficulty
- Medium
- Steps
- 8
What you need
Steps
Park on level ground and let the engine cool fully. Never open the expansion tank cap or bleed screw on a hot engine, as scalding coolant can spray out.
Open the expansion tank cap and check the coolant level. Top up with the correct coolant mix until it sits at the cold mark.
Turn the ignition on without starting the engine. Set the heater to maximum heat and the fan to its lowest speed so the heater valve opens.
Find the bleed screw on the top of the expansion tank or thermostat housing. Loosen it a couple of turns with a 10mm socket or screwdriver.
Slowly fill the expansion tank until coolant trickles out of the bleed screw with no bubbles. Keep the level near the top while it bleeds.
Start the engine and let it idle with the heater on full. Watch the bleed screw and top up the tank as the level drops.
Tighten the bleed screw once a steady stream of coolant runs out with no air. Rev the engine gently a few times and check again.
Let the engine cool, then check the level and top up to the cold mark. Repeat the bleed if the heater still blows cold.
Tips and common mistakes
Air often hides in the heater core, so keep the heater on full heat during the whole bleed.
Only use coolant that meets BMW's spec for the E46 to avoid corrosion in the aluminium engine.
Watch the temperature gauge on the first drive and stop if it climbs past normal.
Questions
How do I know all the air is out?
You get a steady stream of coolant from the bleed screw with no bubbles, and the heater blows hot at idle. Recheck the level after the engine cools.
Can I bleed the system with just water?
Use it only as a temporary flush. Refill with the correct coolant mix afterwards, because plain water raises the boiling point risk and corrodes the system.
Why is my heater still cold after bleeding?
Air is likely still trapped in the heater core. Repeat the bleed with the heater on full heat and the front of the car raised slightly.
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.
