17 11 100 Removing and installing/replacing coolant expansion tank: Notes
WARNING: This page is about a different car, the 2002 BMW Z3 and 2001 BMW Z3. However, it is still accessible from the selected car via links, so may be relevant.
CAUTION:
Danger of scalding! Unscrew expansion tank cap only when engine is cold.
Only drain coolant as far as lower edge of expansion tank, refer to 17 00 005 DRAINING AND TOPPING UP COOLANT