In short the engine will probably need serious work to the head before it will run again.
The reason being that the cam shaft instantly stops turning when the belt snaps leaving the valves static in whatever postion they were in at that time, some open some closed.
The Pistons however keeps moving until the crankshaft stops turning, which if the car is being driven can be some time, and even if stationary ticking over the crankshaft will continue to run for long time.
The results of this will almost invariably be that the pistons strike the open valves with considerable force, either breaking them outright, bending them certainly and always with the possibility that valves will be forced upwards into the camshaft doing serious damage to that also.
Associated damge to the piston faces will result from any such impact and bending of the valves will damage or dislodge the valve guides.
In the hundreds of cam belt failures I have dealt with over the years it has been evident that as technology in engine design progresses the less resilient they become to damage due to cam belt failure and in later years I have only seen a handful that have no visual damage and all on closer inspection have suffered valve stem bending to some degree requiring valve renewal.
So to finalise, there is only one repair for a cam belt breakage and that is prevention, by at least following the makers minimum milage/time requirements for changing them and not waiting till your 'Instinct' tells you the time is right, it will always be expensivly wrong.
Jim, July 2011
