To be honest... I've never had a problem bleeding an M54. I typically fill the system. Heat full, fan full, and leave the fill cap off. Start the car and top off coolant until float comes back up. Close fill cap... let car continue to run until up to temp. After it reaches full temp... crack bleed screw until no more air bubbles come out and heat in the car is blazing hot. Finally, let the engine cool, top off system, and you're done.

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2005 X5 4.4i Build 04/05 Maintenance/Build Log
Nav, Pano, Sport (Purchased 06/14 w/ 109,000 miles) (Sold 8/15 w/121,000 miles)

2006 X5 4.8is Build 11/05 Maintenance/Build Log
Nav, DSP, Pano, Running Boards, OEM Tow Hitch, Cold Weather Pckg (Purchased 08/15 w/ 90,500 miles)

2010 X5 35d Build 02/10
Nav, HiFi, 6 DVD, Sports Pckg, Cold Weather Pckg, HUD, CAS, Running Boards, Leather Dash, PDC, Pano (Purchased 03/17 w/ 136,120 miles)