Polo 9n -doesn't appear to be overheating but...

[htgeng]

This is a 53 plate, 1.4v. A mechanic replaced the coolant sensor after the engine management light was on all the time. It was also causing starting problems if I let the car stand a few minutes and restart it. That fixed the warning light.

When it was giving that problem I noticed that when the engine is idled from cold it takes about 5 minutes for the dash indicator to reach 90c. By this time the flow to the rad is very hot but the return at the bottom is only lukewarm. The cooling fan never seems to kick in at all - only if the A/C is turned on. Yet the dash readout doesn't suggest the engine is overheating.

The mechanic said he will take a look at it again, but I wonder if its just worth replacing the coolant stat as a precaution. Would that cause the cooling fan to stay off?

Was also thinking about having the timing belts + water pump replaced at the same time. Is that good practice? Car has done 51k and I think the belts were replaced in 2006 @ 31k.

 

[Burnerman]

I think this sounds perfectly normal really - the engine will rarely get hot enough when idling to put the fan on - a different matter when you are stuck in traffic though so that is the proper test.
If you want to test the fan at home then keep the engine revving, heater off and it should start to spin at around 100 deg.
Its normal for the fan to come on with the A/C.
As for the belts, at this mileage expect them to be as new really - but if you are going to change the water pump then its a good move, together with the coolant which you can't avoid.
VAG say every 4 years for a belt irrespective of mileage, but again they would!
John