In my 2001 chevy blazer when i start it up there is a weird noise its like a constant tapping almost sounding like its the exhaust but upon closer inspection the noise comes from the drivers side of the engine im thinking it might be a belt and the vehicle seems to be a little sluggish and my gas mileage has gone down any ideas?

 

Valves tapping? Or as my foreign friend likes to call them "vol-vies" . But I digress....Try some Seafoam or Lucas... And I doubt its "a" belt, but if it were, it would be "the" belt. Theres only one.