The tensioner has a spring loaded mechanism inside of it, coil the spring around make sure its hooked. Bolt it back down and make sure it covers the bottom of the spring to keep it from moving out of place anymore.
The tensioner on the Ford Ranger is auto adjusting. There is no manual adjustment. It is usually adjusted by a 1/2" or 3/8" drive rachet. Once it is released all the presure is applied. When you push agaisnt it - it releases the pressure. This is used to change the serpentine belt.
To adjust the tensioner on a Ford Ranger motor, you must find the adjuster bolt located on the back of the tensioner and tighten the bolt so that it pushes the tensioner out and creates more tention.
In general a repair like this isn't easy for someone considers themselves a "novice". If you consider yourself this, you should consult your user manual or call your local mechanic.
I believe that those tensioner are automatic, They have a spring that keep them at the right tension. If it doesn't stay tight you may need to replace it.
To adjust it find adjuster bolt thats located on back of tensioner then tighten bolt so it can push out tensioner and create more tention. If need help consult mechanic.
