Quote Originally Posted by GRHazelton View Post
Having had experience with both timing belts and timing chains, a few observations: chain failure, especially double row chains, is usually gradual and signaled by the clatter of disintegrating links. My guess that single row chains would furnish only seconds of warning.
Depends. Usually chains fail from being worn out. The adjuster reaches the end of its travel and the chain starts to whip, making noise. The whip accelerates the wear, noise increases, etc. The only time I saw a silent chain failure, it was actually a plastic-center-with-metal-tooth-ring cam sprocket on a big old Buick V6 (the derived-from-a-V8 one). High mileage, the plastic got brittle, sprocket collapsed.


I doubt that oil on a belt would cause more rapid failure; synthetic rubbers are pretty robust.
Oh, it does. It weakens the rubber and the highest stress point at the tooth root shears. Very few belts break; they shear some teeth. If the belt breaks it's usually from the abrupt stop when the valves and pistons crash, or from riding off the sprocket after the teeth shear and tangling.