DIY: Coolant Flush

DIY: Coolant Flush

The cooling system should be flushed every 2 years or 30,000 miles. The M54 holds approximately 8.4 liters of coolant.

Parts Needed

• BMW Blue Coolant Concentrate (82 14 1 467 704) — ~4.2 liters
• Distilled water — ~4.2 liters
• New thermostat recommended if over 60k miles

Procedure

1. Allow engine to cool completely
2. Place drain pan under radiator
3. Open radiator drain plug (plastic, bottom of radiator)
4. Remove expansion tank cap to speed drainage
5. Open block drain plug if performing thorough flush
6. Allow complete drainage
7. Close all drain plugs
8. Mix coolant 50/50 with distilled water
9. Fill through expansion tank slowly
10. Fill until level is at MAX mark
11. Start engine with heater on full hot
12. Watch for level to drop as thermostat opens
13. Continue topping off as air bleeds out
14. The E46 is notoriously difficult to bleed — use the bleed screw on top of thermostat housing
15. Run engine to operating temperature, verify no overheating
16. Check level again when cool