I have a 1998 Blazer that makes a godawful noise at times when I start it. It sounds like when it's already running and you try to start it. It doesn't do it every time, sometimes I can go a few days without hearing it and other times it'll do it every time I start it. Kinda getting tired of people looking at me like I'm an idiot 'cause it's already running ! I was told it's the flywheel but these guys don't exactly know what they're talking about. Any suggestions? I don't know the first thing about Chevy's, give me a Toyota and I can fix anything!

 

Does its sound like metal on metal grinding? If is does, you might want to remove the starter and check the teeth on the flywheel. There might be a few that have been grounded down and little and when you start the truck the starter slips.