There is a lock nut on the passenger side above the belts. Its a 12mm bolt with the head pointing to the driver side fender, loosen it by turning it counter-clockwise. There is an adjusting screw that points towards the firewall. Tighten it which will increase tension. Then tighten the lock nut and you should be done.dans200sx said:i have this same problem. one small spray of wd40 onto the belt will silence it for a day or two, but then it comes back. how do i tighten the belt?