Water Pump Diagnosis and Replacement

Cooling System

By Rodney (Mechanics)

The water pump is one of the most important components of the vehicle cooling system. As the heart of your cooling system, a water pump is used to circulate the coolant liquid from the radiator to the engine, which will keep the cool temperature of your engine. If you look inside the pump, you will be able to find an impeller that is made of metal or plastic. This component will push the water to move through the pump. The impeller is inside the pump housing with a shaft assembled with bearings and seals. On most vehicles, you can usually find the water pump mounted on the front side of your engine, and the operation is driven using a belt.

Water Pump Diagnosis And Replacement

Common Problems with Water Pumps

The water pumps can give you trouble in two most common ways. One possible trouble is the breakage of the impeller inside the pump, while the other is possible leaks on the shaft seals after prolonged usage. The impeller’s material may erode, or its blades may come loose. The second problem occurs more on the water pump that uses plastic impellers.

One result that can occur when there is leakage in the water pump is the possible escape of the coolant liquid. If this condition is not fixed immediately, the engine temperature might get too high more frequently from the loss of coolant. The driver of the vehicle might not be able to notice the trouble until the warning light on the dashboard is automatically turned on. If your vehicle is experiencing this problem, you must shut the engine down immediately. If you keep driving your vehicle with an overheating engine, your vehicle might also experience severe engine damage.

Suppose you’ve noticed that your engine is experiencing frequent overheating. In that case, you might need to inspect every component of the entire cooling system, including the water pump, the radiator, and the hoses connected to the components. But, if the coolant liquid leaks from the vent hole or the water pump shaft, the only solution would be to replace the pump. You will not be able to use a sealing product for your coolant system if this problem occurs.

Sealing Failures on Water Pump

The water pump shaft uses a seal to prevent the leaking of your coolant liquid from going past the bearing. But, the sealing material might get worn out due to usage or other deposits, such as rust, sediment, or other contaminating material that might damage the component. Other components, such as the pump shaft or bearings, are also receiving constant heavy load from the timing belt, the drive belt, and the cooling fans. After prolonged usage, the sealing on the water pump shaft can get damaged and let the liquid out.

Most engines are equipped with water pumps that can be used for up to 100,000 miles of travel. But you might also notice the problem after about 50,000 miles of traveling with your vehicle. If you have noticed wobbling on the water pump or the bearings are making weird noises, you might need to replace the pump even though there are no coolant leaks.

Failures on the Water Pump

The water pumps can also experience internal failure inside the component. Some possible causes behind this problem include severe corrosion on the impeller blades, metal fatigue on the shaft due to a flexed fan, or a loose impeller inside the water pump.

Some newer vehicles, especially the ones produced by Chrysler, usually have plastic impellers inside the water pump, which reduce drag and improve the cooling mechanism. But, the plastic material will get worn down easier, especially if the coolant contains abrasive materials. While this condition may not cause leakage on the water pump, the impeller cannot circulate coolant liquid properly, preventing it from maintaining the normal operating temperature in the engine.

An easy way to inspect the condition of your water pump is to find the upper radiator hose and squeeze it when the engine has been idling for a few minutes. You will need to be careful because the hose may be hot. You can then feel the pressure of the circulating coolant inside the hose, especially if you rev the engine. If you cannot feel enough pressure inside the hose, your water pump might be in bad condition. Other possible causes of this problem include a clogged radiator or a bad thermostat that does not open as it should.

Replacing a Water Pump

Getting a proper replacement for the water pump can get difficult since they will come in a wide selection of sizes and shapes. Some water pumps also have different lengths in the shaft. Meanwhile, some vehicles also require a specific water pump style. You will need to match your vehicle’s make, model, engine type, and year to get the proper replacement for the water pump. You can also compare the old water pump you want to replace with a new one you want to buy to ensure they are the same model. Some replacement castings have also employed the usage of mounting bosses and outlets so the model can be used in more engine applications. This type of water pump is usually good enough if it is suitable for use in the original casting.

Old Vs New Waterpump

How to Replace Your Old Water Pump

  1. The first step is to drain the radiator from any liquid by opening the valve that can be located at the bottom part of the radiator. You will need to do this process while the engine is in a cold condition. Ensure you gather the used coolant liquid in a bucket to reuse or dispose of it safely. Usually, used antifreeze liquid can be disposed of by flushing it down the toilet. But, it would help if you never disposed of the antifreeze onto the ground or into a sanitation system. This is because the chemicals might be poisonous to humans and animals.
  2. The next part is removing the fan belt by loosening the pressure on the automatic tensioner. Make sure that you understand the mechanism of how the belt is routed before you start removing the components since you’ll need to reinstall them later correctly. You can do this by drawing a picture of the belt route or taking a picture of the components.

Removing The Waterpump

  1. Remove any component that might disrupt the process of replacing the water pump, including the fan and the shroud, the timing belt cover, brackets, and any other engine accessories blocking your access to the water pump.
  2. Remove the water pump from its location inside the engine.
  3. Make sure you clean every surface in the pump mounting to ensure there is no trace of old gasket seals. Installing a new pump will require a clean and dry surface on the pump mounting.

Clean The Waterpump Old Gasket

  1. Use a gasket sealer on the new pump before bolting it into the engine. It would help to use thread sealers to secure any threads inside the open water jackets.
  2. You can now put coolant liquid into the cooling system. It will usually take some time before all the air inside the engine gets vented out. Some vehicles also utilize vent valves that someone can open to allow air to escape from the cooling system.

New Waterpump Installed

Notes Regarding the Cooling System:

If the problems in the cooling system occur due to rust or sediment in the components, you will have to ensure that the radiator and block have been cleaned and flushed before installing a new pump. It would help if you did this to protect the new pump from the same problems.

If you notice coolant liquid drained from the system is rusty or dirty, avoid reusing the same liquid for the vehicle. Use a balanced 50-50 mixture for the new antifreeze and clean water to refill the cooling system. Avoid using tap water or other types of water containing salts and minerals since those compounds can cause corrosion on the components inside your cooling system.

While replacing the water pump, you might also need to replace the fan clutch simultaneously. It would be best if you did this because the service life of both components is usually the same. Fan clutches that slip frequently prevent an optimal cooling mechanism and cause your engine to overheat frequently.

You might also need to replace the thermostat and the job to replace water pump. Other components that might need to be renewed are the radiator and the heater hoses.