A water pump performs one extremely vital function that ensures your car’s engine works as smooth as possible. The water pump is a vital part of a vehicle’s cooling system, providing a constant stream of coolant to the powertrain. The continuous flow of liquid does not allow the engine to overheat. In other words, if the water pump fails, so does the engine, and that’s what you don’t want.

It helps to learn more about the water pump as a part of the car’s cooling system. If it fails or if there is an issue, you should have a basic idea about all its components and which one to replace.



Main water pump components


A water pump has several small parts that join together to make one working machine. Its most basic components include the hub/pulley, bearing, body/house, seal, and impeller.


The Hub or Pulley


A water pump’s pulley is designed to transfer the drive belt’s movement into the bearing spindle. The pulley receives  the engine traction and acts as a medium between the two, mediating the amount of torque that goes through. Since the pulley experiences a lot of pressure and force from the drive belt, it has to be made of strong materials. The pulley is usually made of steel, cast iron, or sheet metal. The idea is to produce a strong pulley that is lightweight and durable.


Spindle bearing


This is one of the most important water pump components and comes next in line after the pulley. It receives the turning force from the pulley and transfers it to the next component in line, which is the impeller. The bearing’s design and build quality is the sole factor behind the water pump’s lifespan. The bearing is a set of metal balls that turn and twist to do their job.

There are two types of bearings: roller-ball and ball-ball. The roller ball design allows for more durability and smoother function compared with the other. Therefore, most water pumps have a roller-ball design.




The body is the basic structure of the water pump that holds the liquid and where all the transferring takes place. The other components stick to the body to create the water pump that you see with your eyes. Hence, the water pump’s body has to be made of immensely strong materials that can withstand the water pressure produced inside. Water pump bodies are mostly made of lightweight aluminum, but some are built using cast iron. On one end, the body is connected to the pulley, and on the other, it is joined with the car’s cooling system.




Since the bearing is made of metal balls, the risk of corrosion is high. As such, the component needs to be protected from any exposure to liquid. The seal is put in place to protect the bearing from any contamination and to shut the pump tight. If there is any leak, the water pump will not produce sufficient pressure, resulting in failure. Hence, the seal plays an important role in keeping the water pump intact.

Dolz uses the most modern dynamic seals in the market, which ensures long water pump life when it is used with appropriate quality liquid.




The impeller is a rotor that is used to increase the pressure and flow of liquid inside a water pump. In other words, the impeller is the heart of a water pump, and without it, the entire system can fail. It catches the liquid in its fins and increases its flow by turning. The torque is derived from the pulley and bearings. The effectiveness of a water pump is determined by the impeller’s specifications. You need to keep in mind its diameter and the number of fins it has. Both these parts decide the amount of pressure produced by the pump. Impellers are crafted using plastic, metal or cast iron.


water pump components


How to know a water pump is failing?


There are a few factors that can point towards water pump failure in a vehicle:

  • leaking coolant
  • overheating engine
  • smoke from the radiator

If you experience any of the above, chances are that the water pump has failed or is nearing failure. If such a thing happens, you should take your vehicle to a mechanic and get the water pump checked for faults



Keep reading: Top 5 mistakes to avoid when installing the water pump



Dolz, your trusted water pump supplier


Dolz is a giant in the water pump industry serving customers with more than 80 years of experience. The company has successfully fought off its competition, over the years, by making some of the most reliable and durable water pumps. Dolz water pumps are ISO 9001 certified, meaning there is never any compromise on quality or providing customer satisfaction. Dolz makes a wide range of water pumps for both cars and trucks. We have something for everybody.  

Industrias Dolz continues to expand its range, consolidating its position as a leader in the Aftermarket, with the launch of its new electric, variable and auxiliary water pumps.

Dolz has just launched 14 new auxiliary pump references, which are now available on the market. All of them are electric and their function is to cool the passenger compartment. We work together?


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