Checking Pressure Drop In Cooling System:
WARNING: This page is about a different car, the 2003 BMW X5, 2002 BMW X5, 2001 BMW X5, and 2000 BMW X5. However, it is still accessible from the selected car via links, so may be relevant.
Remove cap on expansion tank. Attach special tool 17 0 002 / 17 0 005.
Build up gauge pressure of 1.5 bar, wait approx. 2 minutes.
Cooling system is impervious to leaks if pressure drop is max. 0.1 bar.
Courtesy of BMW OF NORTH AMERICA, INC.