How often does a timing belt need to be tensioned? Is it a case of just adjusting it when replacing and not touching it again? Should the belt be very tight, or should it have play like an alternator belt? Thanks for your time.

 

just once, the leave it. Loosen the tensioner, then rotate the engine so the cam gear moves 3-4 teeth on the belt. This usually tightens the belt enough.

Just use sense....it doesn't need to be crazy tight, but it can't be sloppy either