On certain types of water pumps, Volvo has chosen to make a different type of pulley than usual. This pulley has fewer teeth and protects the timing belt in the belt drive.
In the aftermarket, you may find the same type of water pump in another variant with the usual pulley and a pulley with fewer teeth - both variants can be used and installed without problems.
Should you as a mechanic receive a Volvo water pump with another type of pulley than the one already mounted on the car, then it is not a mistake. You can safely continue the replacement of the water pump.
Remember, as always, when replacing the water pump to clean the cooling system and refill new coolant and deionized water according to the car manufacturer's instructions.
Click here to see a previous article about the importance of cleaning the cooling system.
Waterpump with an usual pulley – with equal spacing between the teeth
Volvo waterpump with fewer teeth on the pulley