Every combustion engine is equipped with a water pump or coolant pump as some call it. This pump is used to circulate coolant within the cooling system to help keep the engine at running temperature during it's normal operation. A water pump is bolted to the front of the engine block or timing chain cover and can be driven by the serpentine belt, timing belt or timing chain. When replacing a water pump that is driven by a timing belt or chain it best to replace the timing belt or chain with a new unit since it will be take off anyway. This will require a diagram which will show you where the timing marks are so you can reassemble the engine correctly.
When a water pump goes bad it can do so in three different ways. The first is the shaft seal which will fail allowing coolant to leak from the pump's weep hole or sealing gasket which is located between the pump housing and the engine block which will cause the engine to overheat. The second failure is the shaft bearing will fail causing a grinding, rumble or squeaking noise. The last way a water pump can go bad is if the impeller either falls off or deteriorates failing to circulate the coolant throughout the engine and radiator.
A water pump endures the rotation speed of the engine and tension against its bearings from the serpentine belt. In time this will wear the water pump out and cause a failure. The main safe seal is subject to coolant system pressure and the heat of the engine which can wear the seal out causing a leak. A water pump will typical last between 80,000 (128747 km) and 120,000 miles (193121 km) in most cases.
The replacement cost of a water pump will vary due to the amount of labor it will take to get to the pump in a particular application. The determining factory is: front or rear wheel drive, (front wheel drive car's are generally tougher due to the limited space to work on the engine) and if the water pump is timing belt or timing chain driven. These jobs can take longer because more if the engine must be taken apart to replace the pump.
If a repair garage or the car dealer is doing the job you can expect to pay between $350.00 and $650.00 (US). If you are doing the job yourself you will need a new water pump which will cost between $65.00 and $130.00 on Amazon or the local parts store. You will also need additional coolant and to rent or buy a water pump pulley holder tool which is also at Amazon for about $20.00 (US). We will show you how to get around the tool is this guide.
There is a video of this job being done at the bottom of this guide.
In most cases you will need to raise the car up using a floor jack and supporting it with jack stands. Its also a good idea to use latex gloves and protective eyewear. Start with the engine cool and the car on level ground. In the guide below the job is being performed on a rear wheel drive car. On front wheel drive car models some of the following steps may not apply. Use a small container to store the screws and bolts so they do not get lost. Also clear a place for the parts that will be removed while the repair is being done.
1. Loosen Radiator Cap
Locate and slowly loosen the radiator or reservoir cap to relieve any residual pressure inside the cooling system. This will also allow the system to drain more rapidly.
2. Drain Coolant
The water pump is submerged in engine coolant so the system must be drained down to avoid spillage when unbolting the pump from the engine block or timing cover. Open the radiator drain valve or remove the lower radiator hose while using a fluid catch basin to drain the coolant into.
3. Disconnect Battery
Anytime you are working on the engine it is a good idea to disconnect the battery to ensure there are no accidental electrical short circuits by contacting power to ground with a wrench or ratchet. You may want to record the radio presets before this step because they will need to be re-entered once the battery is reconnected.
4. Remove Upper Radiator Hose
To help gain access to the water pump a few parts will needed to be removed first. On this car we will start by removing the upper radiator hose first. Also remove any plastic clips or covers to help uncover the engine. Here we are using a hose clamp tool but you can also use a pair of channel locks to do the job.
5. Remove Upper Fan Shroud
Remove the mounting bolts that hold the upper radiator shroud to the radiator and to the lower part of the shroud. In some cases the fan shroud is all one piece which you will be able to remove once the fan blade and clutch is removed.
6. Remove Cooling Fan
The cooling fan may or may not be connected to the water pump. Some cars use an electric fan which will be attached to the radiator fan shroud and will come out all in one piece. In this example the fan is mounted to the water pump. You will need to use a pulley holding tool or as we have done use a large pipe wrench. This is to keep the pulley from turning while loosening the clutch fan nut. Use either a large wrench or the proper tool to remove the fan clutch from the water pump.
7. Remove the Serpentine Belt
Locate the serpentine belt tensioner and while using a ratchet or wrench apply pressure to release the belt from the pulleys. If you cannot find a diagram of the belt's routing use your cell phone a take a picture of the belt and the pulleys so you can install the belt back on when putting the job back together. When replacing the water pump it is a good idea the replace the serpentine belt since it will be off already.
8. Remove the Water Pump Pulley
The water pump pulley must be held in place to break loose the mounting bolts. This can be done by using a large standard (flat blade) screwdriver and wedging it in between the bolts and the center thread. Then use a socket or wrench to loosen and remove the bolts. Once the bolts have been removed lift the pulley from the water pump. On Some water pumps like a GM V6 or V8 the pulley in stay on the water pump and cannot be removed.
9. Remove the Water pump
This will expose the water pump and the mounting bolts. There may be additional hoses, brackets and covers that need to be removed depending on design which you will need to look at and decide if they need to be taken off or not before the pump can be removed.
Locate the bolts that hold the water pump to the engine block or timing cover. Use a socket or wrench the remove the bolts counterclockwise. Take note on which bolts come out of which location because some bolts can be different lengths which can create problem during reassembly.
Once all of the mounting bolts have been removed shock the pump to break the seal which will enable the pump to be removed from it's location. Using a small hammer gently tap the pump housing or fan mounting flange to help break the seal. A small amount of coolant will also be released so have your fluid catch pan ready.
Grasp the water pump and wiggle it loose and be careful no to drop it because it could roll into the radiator and cause a leak taking the fun out of the job.
10. Match the New Water Pump
Remove the new water pump from the box and match it to the old pump. Check the mounting flange for the fan clutch and the gasket surface they should match identically. Also, a new gasket or O ring will be included with the new water pump. This will help seal the pump to the block or timing cover and avoid leaks.
Install the new gasket or O ring seal while making sure not to damage the integrity of either the gasket or the seal. This step is important because if you cause a leak you will be doing the job over again.
11. Install New Water Pump
Now that the new water pump is ready to be installed you must prepare the engine block or timing cover. This means cleaning the sealing surface for the new O ring seal or gasket to mate against. Use a shop towel and wipe away any dirt and grease from the area. If the water pump uses a gasket use a gasket scraper to remove the old gasket until the metal is clean and smooth. Then use a small amount of gasket sealer (silicone rubber) while mounting the gasket to the pump. This part is as equally important as preparing the water pump for installation.
Lower the new water pump down into the engine bay and gently insert it into the engine block or timing cover and push it into place. Insert one of the pump's mounting bolts to help keep the unit in place and tighten it by hand, follow up with the remaining bolts. Be sure to insert the right length bolts into their rightful place or damage can occur when tightening the bolts.
Use a wrench or ratchet to tighten the mounting bolts in a even cross pattern and torque to factory specification which is usually between 19 and 22 foot pounds.
If your water pump is equipped with a detachable pulley reinstall the pulley back onto the pump and insert and tighten the mounting bolts in a cross pattern. Use a large flat blade screwdriver to hold the pulley from turning while tightening.
12. Finish Reassembly
Reinstall the serpentine belt and the fan clutch in the same way it was removed. Again this would be a good time to replace the belt with a new one since it is off already. Also many mechanics feel this is a good time to replace the thermostat, coolant hoses and flush the radiator for safe measure since the cooling system has already been opened. Reassemble the upper fan shroud and any other plastic clips and guards. Make sure everything is out of the way of the fan blade area.
13. Refill Coolant
Reinstall the upper and lower radiator hoses and double check the job. Then start adding coolant while looking under the car for any obvious leaks. Once the reservoir is full, step back from the engine compartment and start the engine. Watch the level of the coolant and add more as needed while allowing the engine to warm up to operating temperature.
Once the engine is warm the thermostat will open and there may be a drop in the coolant level. After topping the reservoir or radiator off install the radiator cap with the engine still running. Drive the car for a few days and then double check the coolant level once the engine has cooled down. This would be a good time to check the job for leaks.
Here is the job being done by one of our mechanics.
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