VW / Audi 1.8T Overheating
Here’s a common, common problem with VW and Audi’s cooling systems. Their water pumps use plastic impellers to pump the engine coolant and, unfortunately, the impellers like to crack and freewheel on the pump’s shaft. This will obviously cause overheating problems. Sometimes this can be hard to diagnose because, if the impeller still moves a little, the car will only overheat under certain conditions.
This waterpump, like many in the VW/Audi world is driven by the timing belt and these two services should be done together to save on the labor costs as well as to ensure a more reliable engine.
Note: At Integrity First Automotive we have a great relationship with a parts suppler than can provide us with aftermarket water pumps that use METAL impellers – they are our preferred replacement for these engines.
Below is a picture of a VW water pump with a broken impeller. This one is from a New Beetle with the 1.8T APH engine: