99 z3 2.8l roadster

[Sijray21]

Bleeding an M52-ish BMW engine is annoying.

Get the nose HIGH in the air (parking on a very sloped driveway works too). Heat to full blast. Bleed screw open on expansion tank. Fill the tank, run it, rev it, the thermostat will eventually open and start sucking water down. Keep filling the tank. It will piss coolant everywhere out of the bleed screw kind of by design. Yes, this is messy and annoying, but you'll see bubbles come out too. Eventually the bubbles will stop and you'll be done. Take it for a good hard romp around your area and check level once it cools.

Just curious, but why would putting the nose high in the air help? wouldn't that put the radiator and t-stat in the position to have all the air there? i could see that with other M52s that have a secondary bleeder screw near the t-stat housing, but the z3 doesn't have that. having the car level seems that the highest point in the cooling system would be expansion tank, no?