With the tensioner installed push (some force required) the center of the tensioner piston inward several times with a screw driver until the piston releases. When the piston releases it will move outward and put tension on the chain. If you are not able to get the piston to release, buy a new tensioner from autozone, which is what I had to do. The new tensioner works the same way and worked great for me. Vehicle: 1997 Chevy Cavalier 2.4L
