I have a 2004 GMC Envoy that has just had the oil changed, the cam sensor and cam-shaft actuator replaced 3000 miles ago. Just recently when the engine is cold and I try to start it, it makes a scraping sound while the engine is trying to turn over. It only does it while the engine is cold, but once it warms up, and every re-start throughout the day is perfectly fine. I am however replacing the drive belt and checking all of the pullys tomorrow. If thats not it, what else could be the problem?