The heart of the cooling system of your vehicle is the water pump, and as a key part among its components to carry out its function, there is the water pump impeller.

What does the water pump impeller do?


In a water pump, the impeller is the part that distributes coolant throughout the cooling system of the vehicle. And it must be properly designed to provide the correct system pressure for all driving conditions.

The rotating vanes on this small, round disc assist in moving the coolant through the cooling circuit and thus cool the vehicle’s engine. When this component fails, the coolant supply is cut off, causing the engine to overheat. As you know, the health and efficiency of your vehicle’s engine requires an optimal temperature. Without it, it could cause serious and irreparable damage.

The impeller is made up of several curved blades. The coolant flows through the turbine along its axis and escapes between the fins along the circumference.



Keep reading: Types of automotive water pumps



Water pump impellers: Types


All water pumps are not the same. Some are made with plastic impellers while others have metal. The impellers manufactured in DOLZ are made from injected plastic, cast iron or aluminum passivated depending on the original OEM design. Besides, depending on the diameter, number and height of the fins, and other specifications, it will determine the type of impeller. 

So, let’s get to know which are the two main types of water pump impellers: open impeller and closed impeller.

  1. Open turbine

An open turbine has blades that are open on both sides and also lacks a protective cover. It is a type of turbine that, as a general rule, is found in smaller water pumps and that also are not subject to much stress. Although there is also the possibility of finding them in larger water pumps.

  1. Closed turbine

On the other hand, the closed turbine is completely covered at the front of the part and offers maximum resistance. They are generally the most popular type of turbine for large pumps that move coolant, although smaller water pumps can also be found. Thus, thanks to its design, axial thrust is reduced, which can increase the useful life of the bearing.


pump impeller


How to know if a water pump impeller is malfunctioning?


Though impeller failure is not common, it can happen when the impeller blades slip when the engine is started. Impeller corrosion can also occur from unsuitable or deteriorated coolant. So, when you have a bad impeller, you can have a lot of troubles.

If your impeller fails, the pump will be unable to provide coolant to the engine, causing it to overheat. You may be able to avoid serious difficulties if you notice that your water pump is failing early on. However, if you overlook a bad impeller in time, the consequences might be disastrous for your engine. There are five symptoms that your cooling system needs attention.

  • Pump leakage
  • Slow re-priming
  • Unusual noises or vibrations
  • Overheating
  • Reduced pump flow

It’s also possible for the impeller to become loose on the shaft, so although the impeller looks well, it doesn’t pump anything! Dolz TIP: You will pay the price later if you keep your water pump impeller going with patchwork repairs and makeshift remedies, and you have to pay it later. While you may be under pressure to keep production going, these temporary repairs will not prevent the pump from failing.

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Think of it like insurance and protecting your investment. For that, Dolz recommends replace the water pumps and prevent future problems for your vehicle.

If you need further information or have any technical question with the water pump impeller, please contact us and our team will help you.