It is important that the timing belt is not worn, because it can cause it to snap and at worst it will damage the pistons and valves. The belt wears each time the engine starts, and therefore the belt should be replaced at a certain mileage. It is stated in your BMW's service book how often the belt must be replaced. It is possible to replace the timing belt yourself, but it is one of the tasks that is not recommended to get started on, unless you are 100 percent certain of how the job needs to be done. Read on to find out how to obtain 3 free quotes from quality garages near you so that you can compare prices and choose the best one.