
Water Pump Replacement – BMW B46/B48 Turbo 4 Cyl. Engine
Step 1 - Purchase Parts

Water Pump and Pulley
When it comes to engine parts, we firmly stand behind only using Genuine BMW. Genuine BMW are manufactured to a completely higher standard than the obscure aftermarket ones found on Amazon and Ebay. Don't be fooled by the lower prices..."imported" aftermarket water pumps will fail and honestly are in our opinion complete junk. This is a Genuine BMW factory water pump that is the exact same one installed at the dealership and guaranteed to give years of uninterrupted service.
Step 2 - Repair Procedure

Before starting this repair, the coolant system must be drained.
Please see our article Coolant Flush and Replacement - BMW B46/B48 Turbo 4 Cylinder Engine for detailed instructions on draining and refilling the cooling system.

- Pull the acoustic engine cover loose from the mounting points as shown in the image and remove from the vehicle.

- Locate the water pump pulley. Loosen (do not remove) the three mounting bolts (1) as shown in the image.

- Locate the belt tensioner on the front of engine behind the vibration dampener pulley. the tensioner has a boss on the front of it that when turned clockwise will release the pressure on the drive belt.

- Use a socket wrench to turn the belt tensioner (1) boss clockwise to release tension on the drive belt.

- Remove the drive belt (1) from the water pump pulley.

- Remove the vacuum hose (1) from the side of the water pump.

- Remove the mounting bolts (1) from the water pump pulley. Remove the pulley from the engine compartment.

- Remove the four bolts anchoring the water pump to the engine.
- Grasp the water pump and remove it from the engine compartment.

- Make sure that the old o-ring (1) is removed from the engine. There will be a new o-ring supplied with the new water pump.

- Make sure the surface of the engine where the water pump mounts is thoroughly clean and free of grease.

- Water pump to engine mounting bolts torque to 8.8 Nm (6.5 ft-lb)
- Water pump pulley to water pump torque to 8.8 Nm (6.5 ft-lb)
- Replace coolant and bleed system following instructions in our article Coolant Flush and Replacement - BMW B46/B48 Turbo 4 Cylinder Engine.