Lack of coolant flow
Like too many modern vehicles, this 2001 VW Beetle is not fitted with a coolant temperature gauge. The lack of this gauge was hiding the fact that the coolant temperature was slowly creeping upwards. Only when the red warning light illuminated did the owner realise that something was wrong. As the light went off again, she kept driving but did bring the Beetle to us the next day.
Plugging in our scanner, we read off a temperature of 120°C, and as there seemed to be a good coolant flow, we didn’t believe the thermostat was at fault. Only when we felt the very bottom of the radiator did we discover that the coolant flow was restricted.
At this stage, we were convinced the water pump impeller had failed. We have seen this before, and with this little Bug just about due for a new timing belt, it didn’t take too much to persuade the owner that we should strip it down with a view to replacing the timing belt and water pump.
Once the pump was removed, our suspicions were confirmed and we discovered the impeller sitting in the water jacket in two pieces.