Checking pressure relief valve in sealing cap
WARNING: This page does not describe the selected car, but rather 15 other vehicles, including the 2015 BMW Alpina B7L, 2015 BMW Alpina B7, 2014 BMW Alpina B7L, 2014 BMW Alpina B7, and 2013 BMW Alpina. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
While the driving at high ambient temperatures, the design may cause the pressure relief valve in the sealing cap to open slightly and air together with dissolved coolant to escape. This coolant vapor condenses on the surface of the expansion tank and leaves toes when the vehicle has cooled down. These toes do not indicate whether the sealing cap is defective or not. When the vehicle has been in standstill for an extended period of time, the residual escaping coolant can cause the pressure relief valve in the sealing cap to stick; therefore repeat the test procedure for the sealing cap 2 to 3 times.
Replace the sealing cap only after you have checked three times and there is an incorrect opening pressure.
Replace the sealing cap only after you have checked three times and there is an incorrect opening pressure.
Screw sealing cap (1) onto special tool 17 0 114.
Build up pressure with special tool (hand pump) 17 0 101; observe pressure gauge to ascertain when opening pressure is achieved.
Compare OPENING PRESSURE of pressure relief valve.