UK Car Repair: fan belt, grooved pulleys, vauxhall corsa

Question
Vauxhall corsa 1.4 16v GLS R reg. My fan belt has come off, can you tell why this has happened and how the belt fits, or a diagram would be a great help.

Answer
Did it break or just come off?  Do you have a new belt to fit?  I do not have access to info on your car but you should be able to figure it out by trial. First you have to release the tension on the spring adjusting pulley, this normally requires a long extension and a socket. Before doing this you can see that the belt starts at the crankshaft, the grooved side fits into the grooved pulleys and the flat side moves over the polished pulleys. Do a simple diagram on a sheet of paper and you will see there is only one way that it can fit.