This is related to my other question. Since this has a mechanical water pump how is the system supposed to be bled by the book?
May 19, 2026 at 9:15 PM
Coolant bleeding?
2018 BMW 330
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BMW service information strongly favors vacuum filling the cooling system on these engines. This pulls air out first, then draws coolant in, which helps prevent air pockets in the main engine cooling circuit.
Because the main pump is mechanical, coolant flow through the main engine circuit requires the engine to run. So after filling, you run the engine and allow it to circulate coolant.
Set:
Heater temperature to maximum
Blower on low
Coolant cap installed once level is stabilized enough
Monitor coolant temperature with scan data if possible
Then let the engine idle and bring it up carefully while watching temperature.
Because the main pump is mechanical, coolant flow through the main engine circuit requires the engine to run. So after filling, you run the engine and allow it to circulate coolant.
Set:
Heater temperature to maximum
Blower on low
Coolant cap installed once level is stabilized enough
Monitor coolant temperature with scan data if possible
Then let the engine idle and bring it up carefully while watching temperature.
May 20, 2026 at 4:25 PM
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.