Now there are two types of radiator cooling fans - motor driven, and belt driven. The belt driven are just that - driven by a belt that is powered by the engine, and it stays on irrespective of whether the coolant is cool or hot. The newer vehivles all have motor driven fans, that work selectively based on whether the coolant temperature is hot enough to need the fan, or not. There is a sensor in the coolant circuit, which decides when the fan will run and when it will stop. This type of fan DOES NOT NEED A BELT.
Now looking at both the types, your assertion about letting the fan stop before switching the engine off looks odd, except for the case where the coolant temperature is high, and the motor driven fan is working. If you switch off the engine then, the fan will stop. But as the heat source of the engine is also stopped, eventually the engine will cool down and nothing will go wrong as such. The belt driven fan anyways cannot stop unless you stop the engine.
I am as confused as I was before we started. Mostly the mechanic gave you some 'gyan' just for the heck of it. It may not necessarily be a very important tip.
|