Cooling problem

QA couple of years ago, I bought my 2004 VW Polo 1.2 with the AWY engine and 64,000 miles, inspired by the ‘bangernomics’ movement. I’ve managed to maintain it myself, including servicing, fitting a new exhaust, diagnosing and replacing a faulty O2 sensor, performing a full rear brake overhaul and making some bodywork repairs.

It was noted at the last MOT that the cooling fan was not kicking in, so I investigated. By jumping the switch, the cooling fan now works fine. I noticed the thermostat housing and lower radiator hose were cool, so I assumed this was the cause and replaced the housing and thermostat, but there was no change. Finally, although the cabin heater works well, I pulled off the water pump and checked it, but it was fine. While it was off, I flushed the radiator from top and bottom, and the engine block from the thermostat housing. On refilling the system, I noticed it only took about 2.5-3 litres of coolant, whereas the Haynes manual says it holds 5.1 litres. Can you help?

Brian Shepherd

AThe coolant capacity stated will be the total capacity from dry. When refilling a system which has been in use, coolant will remain in many areas of the engine, reducing the amount needed to refill the system. Three litres of coolant I would expect it to take after being drained.

I am assuming that the coolant system is now performing correctly. You do not mention the temperature reading of the engine, but there would only be cause for concern if this was reaching around 100°C without the cooling fan operating.

Having checked the water pump, and flushed the system, you shouldn’t have any further problems. You should ensure the system is correctly bled by topping up and then running the engine at a fast idle for around five minutes with the coolant reservoir cap removed.

The only concern if the temperature is rising and the coolant isn’t circulating is that the thermostat isn’t working correctly. I have come across faulty new thermostats in the past – worth checking.