I have an 07 new body style Silverado half ton 4 by 4. Has a 4.8 L Vortec and has recently acquired a scrape towards the front of the motor. Took all the belts out to make sure was not pulleys or water pump or alternator. Scrape is still there. Took it to a shop and they listened to it and said they thought a cam bearing was coming out of his journal in the cam was eating it. Is this a possibility. I hate to pull the motor and tear it all apart and find out that's not the issue. Any suggestions would be greatly appreciated.