| Sparkin,
Don't worry, it's all fine
As you rightly say, the rad has the pressure cap, the bottle is purely for overflow. Under pressure the water is pushed past the rad cap an into the overflow. As the system cools, it creates vacum and pulls the requisire amount of water back from the overflow bottle. That's why the overflow pipe feeds into the bottom of the overflow tank.
The fan cutting in when you switch off is due to heat soak. Many bike/cars do this; again, no problem, and to be expected on hot-ish day or after a town bimble.
Rgds, Rob
Rgds, Rob | 
Hybrid Mode
