WHY USE WATER PUMPS WITH METAL IMPELLERS

Why use VW and Audi waterpumps with metal impellers?

plastic impellers tend to be less robust than metal impellers

What is the function of a water pump?

The water pump circulates coolant between the engine and the radiator and part of the water pump is an impeller which rotates, thereby circulating the coolant.
You can see the impeller on the above photo – it is on the end of a shaft in the top right hand corner.
Impellers are made either of plastic or metal.

In our experience, plastic impellers fail more quickly

The photo above shows a Audi A3 1.8T Water Pump with a plastic impeller which has cracked. Clearly; this is not good.
In our experience as an independent VW Audi Specialist, we have found that water pumps with plastic impellers appear to fail more quickly than those made of metal. This would seem to imply that the benefits of saving weight by using a plastic instead of cast metal impeller could be over-rated…
We ourselves only use German manufactured Hepu water pumps, all of which have metal impellers (-not plastic!)

What are VW and Audi forums saying about the water pumps debate?

If you are a frequent visitor to any number of the VW and Audi owner forums, you will not have missed the debate. Click on the below button to read what various UK and US VW and Audi forums have said about plastic vs metal impellers