That water pump didn't fail when the engine was running-the impeller crack is a clean break, not chewed up, no visible damage to the inside of the housing. Lucky, too, because if it had failed while it was running it would have launched shrapnel throughout the cooling system, maybe even destroyed the front cover. This is why I'm not a big timing belt fan, bad things happen when components fail, fortunately the truck's owner dodged a bullet this time, next time he might not be so lucky!