Hi i have a 2004 ford ranger, its done 126,000 been a good truck, just lately from cold there is a tapping noise coming from the top of the engine from cold to hot had the timing checked and had the belts replaced, noise went. 800 miles later noise is back. took it back to garage took belts off and checked thought it was the air con tensioner pully but then noise came back. it is not constant is sound like every revolution almost a bolt rattling in the engine. noise is only when it is cold! any ideas please help!