Cool Running E39 M54 Bleed Procedure

An issue has popped up in 525i. I noticed the engine was slow to come up to temp. One observation initially was it would run cool, slightly above the first hash on the gauge and after a short run, 10 miles, and brief shut down, upon restarting the gauge would come up to temp as normal. I surmised an air issue in the cooling system which was affecting the thermostat. I followed a video on Youtube which showed a bleed procedure but I would like more clarity. In may be in fact not an air issue but a lurking thermostat failure.



There are two bleed screws, one on the hose leading to the thermostat and one on the expansion tank at the adjacent to the fill cap. With the engine slightly warm, and heater circulating fluid, I did relieve some excess air from the valve on the hose. After I observed a stream of our antifreeze after several top offs of the expansion tank, I closed the valve an focused my attention to the bleed screw on the tank, which I suspect is just to assure proper tank level. I still experience a cool running engine albeit, slightly warmer but definitely on the cool side. Can anyone expand on what I am seeing? How long should I wait when bleeding to be assured I have done all I can to purge air? Any comments would be greatly appreciated.

Cool Running E39 M54 Bleed Procedure