Genuine OEM BMW Crank Pulley Washer, part number 11231709977. This washer is used to provide proper spacing and secure fastening for the crankshaft pulley, ensuring it is correctly aligned and mounted. It is a critical component for the engine's timing and accessory drive system. The washer weighs 0.112 kg. Genuine OEM washers are manufactured to exact specifications with high-strength materials to withstand the forces involved in engine operation and ensure the crankshaft pulley remains securely in place.