just replaced the valve covers and after that removed the A.I.R. system (broken,cracked, and not doing anything useful) before we took of the air, we noticed a faint ticking noise but it is nothing compared to when we took the air off. we are thinking it is an exhaust leak but it was smoking before and that is why we replaced/removed those items. could it be just a loose bolt going into the air port or could we have done something while the valve covers were off and got worse by sitting for less than a week