I found this great answer, the second one: http://www.justanswer.com/honda/1k3fw-change-alternator-belt-2003-honda-civic.html
On part (7) and (8) it says to turn the belt adjusting bolt counter-clockwise to loosen the belt. But how do I gauge the bolt and belt tension after I put the new belts on? How do I know when I've screwed the bolt enough, too much or too little?
Thank you
In the diagram which they posted:
You are looking for the deflection point at "A". Normal deflection is considered about 1/2" (or just under 2cm). As the guy in the instruction says, tighten up the belt, then run the engine for about 5 minutes, then readjust the belts again.
If the belt is too tight, you are putting extra wear on the belt and accessories. If the belt is too loose, you run the risk of the belt jumping off, extra belt wear, and/or an accessory slipping, which means you'd not be getting the best performance out of any part of that which the belt drives.
