The Best Ways to Check a Faulty Water Pump on a BMW

1. Park your BMW in a safe location on even ground. Engage the parking brake and apply blocks to the wheels of the vehicle.
2. Turn on the ignition. Allow the vehicle to idle for at least 10 minutes or until the engine warms up. Look on the ground underneath the vehicle near the engine area for coolant. A coolant leak is one of the most obvious signs of damage to the water pump.
3. Walk around to the hood area of the vehicle while the engine is still running. Locate the coolant reservoir near the upper engine area attached to the radiator hose. Remove the coolant cap. Check the coolant level in your vehicle. The coolant reservoir should be nearly full, which would be an indication that there is no leak in the water pump.
4. Locate the pump shaft of the water pump. An easy way to locate the pump shaft is to trace the radiator hose from the coolant reservoir until you reach the front of the engine. The water pump is mounted to the front of the engine. Identify the pump shaft as the component that attaches the water pump to the fan assembly.
5. Place a mechanic’s stethoscope on the pump shaft while the engine is running. Listen for clunking sounds, which is an indication of a faulty bearing inside the water pump.
6. Pinch the upper radiator hose where it connects to the engine using your fingers. Hold your fingers on the radiator hose for at least 60 seconds. Feel for a pressure surge in the radiator hose. Ideally, the water pump should attempt to pump coolant and you’ll feel the pressure surges in the radiator hose.
7. Grab the pump shaft of the water pump with your hand. Shake the pump shaft gently. There should be little to no movement in the pump shaft. If your pump shaft rocks under pressure, this is an indication that your water pump bearings are faulty.