BMW 316i F30 N13 coolant pump replacement

Car: BMW 316i F30 /2012, N13 engine Water pump part number: 11517648827 Water Pump Pulley part number: 11517619020 Venting cooling system Filling without vacuum filling unit: - cold engine. - Open bleeder screw on coolant expansion tank. - Top up the cooling system to the lower edge of the expansion tank until the coolant level in the expansion tank no longer drops. (I added over 4 liters of coolant to the MAX level) - Connect battery charger. - Switch on ignition and low-beam headlight. - Switch off the air conditioning. - Set heater to maximum temperature and turn blower down to lowest speed. - Driving experience switch must not be set to ECO PRO! - Wait for approx. 1 min. (I expected the auxiliary electrical pump to circulate the coolant but this didn&seem to happen) - You may need to top up the coolant to the lower edge of the expansion tank. (coolant level did not drop) - Tighten bleeder screw on coolant expansion tank. - Close coolant expansion tank. - Start engine. - Draining procedure: Press accelerator pedal 10x up to approx. 3000 rpm 1 s increased idle to approximately 1200 rpm Press accelerator pedal 10x up to approx. 3000 rpm 1 s increased idle to approximately 1200 rpm Press accelerator pedal 10x up to approx. 3000 rpm - Stop engine. - Fill coolant expansion tank to 100 ml above maximum. (I filled it again to the MAX level) After this I took a drive to circulate and bleed the coolant with the heater set to maximum temperature) until I got the coolant...