I'm in trouble with my car, which the mechanics failed to resolve now.And question is: Command valve was full of grooves and rocker arms were worn out (imagine that caught the rocker and the command continues to run, so friction wear some of the rockers), the car was making an awful noise, as if a piece of iron shakes loose inside the engine. I changed the command and two rockers. The same problem appeared again, and two rockers were replaced under warranty. The car is now in the workshop to try to discover what it is. I bought the car five months ago, but I take the car in the same workshop that took the former owner, because there was a sticker. Before selling to me, the owner replaced the head with a new, do not know if there is any relation to the problems I'm facing ...

I hope you can help me.
hug