Water pump pulleys are designed to be driven by a drive belt or serpentine belt. Without a pulley, a water pump will not rotate unless it is driven by the timing belt, timing chain, or an electric motor.
There are two types of pulleys used to drive an engine’s water pump:
- V-groove pulley
- Multi-groove pulley
A v-groove pulley is a single depth pulley that can only drive one belt. Some v-groove pulleys can have more than one groove, but each groove must have its own belt. If a belt breaks off or a pulley breaks, then only the circuit with the belt is no longer operational. If the alternator belt breaks off but the water pump belt does not break, then the engine can still run as long as the battery still has a charge.
A multi-groove pulley is a multi-depth pulley that can only drive a serpentine belt. The serpentine belt is useful because it can be driven on its front and back sides. The serpentine belt design serves well, but when a pulley breaks or the belt breaks off, then all of the accessories, including the water pump, fail.
As the water pump pulley wears out, it tends to widen, making the belt slip. Cracks can also form on the pulley if the bolts come loose or the pulley has too much stress applied to it. Additionally, the pulley can bend if the belt is at an angle because of an accessory that is not aligned properly. This will cause the pulley to have a wobble effect. Other signs of a failing water pump pulley include a grinding noise or the engine overheating.
Part 1 of 4: Preparing to replace the water pump pulley
Having all of the necessary tools and materials prior to starting the work will allow you to get the job done more efficiently.
Materials needed
- Allen wrench set
- Boxed end wrenches
- Breaker bar
- Flashlight
- Jack
- Jack stands
- Protective leather gloves
- Ratchet with metric and standard sockets
- Replacement water pump pulley
- Serpentine belt remover tool specific to your vehicle
- Torque wrench
- Torx bit set
- Wheel chocks
Step 1: Inspect the water pump pulley. Open the hood to the engine compartment. Grab a flashlight and visually check the water pump pulley for any cracks and to see if it is out of alignment.
Step 2: Start the engine and test the pulley. With the engine started, check whether the pulley is working correctly. Watch for any wobbling or note if it makes any noises as if the bolts are loose.
Step 3: Position your vehicle. Once you have verified a problem with the water pump pulley, you will need to position the vehicle. Park the car on a flat, hard surface. Make sure that the transmission is in park (for automatics) or in first gear (for manuals).
Step 4: Secure the wheels. Place wheel chocks around the tires that will be remaining on the ground. In this case, the wheel chocks will be around the front tires since the rear of the vehicle will be lifted up. Engage the parking brake to lock the rear tires in place and keep them from moving.
Step 5: Raise the vehicle. Using a floor jack that is recommended for the weight of your vehicle, lift the vehicle at its specified jacking points until the wheels are completely off the ground. For most modern cars, the jacking points will be on the pinch weld just under the doors along the bottom of the car.
Step 6: Secure the vehicle. Place jack stands under the jacking points, and then you can lower the vehicle onto the stands.
Part 2 of 4: Removing the old water pump pulley
Step 1: Locate the water pump pulley. Find the pulleys to the engine and look for the pulley that goes to the water pump.
Step 2: Remove any components in the way of the drive or serpentine belt. To access the drive or serpentine belt, you will need to remove any parts that are in the way.
For example, on front-wheel drive vehicles, some belts go around dogbone engine mounts; these will need to be removed.
For rear-wheel drive vehicles:
Step 3: Remove the belt from the pulleys. First, locate the tensioner to the belt. If you are removing a serpentine belt, you will need to use a breaker bar to turn the tensioner and relax the belt.
If the vehicle has a v-belt, you can simply loosen the tensioner to relax the belt. Once the belt is loose enough, remove it from the pulleys.
Step 4: Remove the clutch fan. If you have a clutch fan or flex fan, remove this fan using protective leather gloves.
Step 5: Remove the pulley from the water pump. Remove the mounting bolts that secure the pulley to the water pump. Then you can pull out the old water pump pulley.
For front-wheel drive vehicles:
Step 3: Remove the belt from the pulleys. First, locate the tensioner to the belt. If you are removing a serpentine belt, you will need to use a serpentine belt removal tool to turn the tensioner and relax the belt.
If the vehicle has a v-belt, you can simply loosen the tensioner to relax the belt. Once the belt is loose enough, remove it from the pulleys.
- Note: To remove the pulley bolts, you may have to go under the vehicle or go through the fender near the wheel to access the bolts.
Step 4: Remove the pulley from the water pump. Remove the mounting bolts that secure the pulley to the water pump. Then you can pull out the old water pump pulley.
Part 3 of 4: Installing the new water pump pulley
For rear-wheel drive vehicles:
Step 1: Install the new pulley onto the water pump shaft. Screw in the pulley mounting bolts and hand tighten them. Then torque the bolts to the recommended specifications that should have come with the pulley. If you do not have any specs, you can torque the bolts to 20 foot pounds and then an additional 1/8 turn.
Step 2: Reinstall the clutch fan or flex fan. Using protective leather gloves, install the clutch fan or flex fan back onto the water pump shaft.
Step 3: Replace any belts onto the pulleys. If the previously removed belt was a v-belt, you can just put the belt onto all of the pulleys and then move the tensioner to adjust the belt.
If the previously removed belt was a serpentine belt, you will need to put the belt on all of the pulleys but one. Find the easiest pulley within reach to have the belt next to before installing.
Step 4: Complete the reinstallation of the appropriate belt. If you are reinstalling a serpentine belt, use the breaker bar to relax the tensioner and slide the belt onto the last pulley.
If you are reinstalling a v-belt, slide the tensioner over and tighten it. Make adjustments to the v-belt by loosening and tightening the tensioner until the belt is loose to its width or about a 1/4 inch.
For front-wheel drive vehicles:
Step 1: Install the new pulley onto the water pump shaft. Screw in the mounting bolts and hand tighten them. Then torque the bolts to the recommended specifications that should have come with the pulley. If you do not have any specs, you can torque the bolts to 20 foot pounds and then an additional 1/8 turn.
- Note: To install the pulley bolts, you may have to go under the vehicle or go through the fender near the wheel to access the bolt holes.
Step 2: Replace any belts onto the pulleys. If the previously removed belt was a v-belt, you can just put the belt onto all of the pulleys and then move the tensioner to adjust the belt.
If the previously removed belt was a serpentine belt, you will need to put the belt on all of the pulleys but one. Find the easiest pulley within reach to have the belt next to before installing.
Step 3: Complete the reinstallation of the appropriate belt. If you are reinstalling a serpentine belt, use the serpentine belt tool to relax the tensioner and slide the belt onto the last pulley.
If you are reinstalling a v-belt, slide the tensioner over and tighten it. Make adjustments to the v-belt by loosening and tightening the tensioner until the belt is loose to its width or about a 1/4 inch.
Part 4 of 4: Lowering the vehicle and testing the repair
Step 1: Clean up the work area. Collect all tools and equipment and place them out of the way.
Step 2: Remove the jack stands. Using your floor jack, lift the vehicle at its specified jacking points until the wheels are completely off of the jack stands. Remove the jack stands and move them away from the vehicle.
Step 3: Lower the vehicle. Use the jack to lower the vehicle so that all four wheels are on the ground. Pull the jack out from under the car and set it aside.
At this point, you can also remove the wheel chocks from the rear tires and set them aside.
Step 4: Test drive the vehicle. Drive the vehicle around the block. While you are driving around, listen for any unusual noises that could be caused by the replacement pulley.
- Note: If you put the wrong pulley on and it is bigger than the original pulley, you will experience a loud chirping noise as the drive belt or serpentine belt pulls on the pulley.
Step 5: Inspect the pulley. When you are done with the test drive, grab a flashlight, open the hood, and look at the water pump pulley. Check to make sure that the pulley is not bent or cracked. Also, make sure that the drive belt or serpentine belt has been properly adjusted.
If your vehicle continues to make noises after you have replaced this part, then there may be further diagnosis of the water pump pulley. If this is the case for you, or if you would simply rather have a professional perform this repair, you can always have one of the certified technicians at YourMechanic come and diagnose or replace your water pump pulley for you.
