I found this on another website. You need a belt tension gauge. Napa has one called a Krikit II which runs about $14 and fits in your pocket like a pen. New belts, ones with less than 15 minutes on them need to be adjusted to 190lbs. Used belts need to adjusted to 160lbs. After 3 week he said his sat at about 170lbs.
After somemore investigation is turn out the Krikit II deflection gauge is made by Goodyear.
Here is a link: http://www.goodyearindustrialproducts.com/polyurethanebelts/bt_method3.html
I'd check with Jeep to comfirm the lbs. of deflection.
Should have an automatic belt tensioner - if tension not correct replace tensioner
Your belt is probably stretched or the tensioner is weak. Try a new belt, or replacing the tensioner. If it is still loose get a 1/2 inch smaller belt.
A Wrench!! takes awhile and it is cramped but that is the way to do it!
If it is a serpentine belt - adjusts automatically through belt tensioner If not check the alternator for adjuster or Power steering pump
The belt tensioner is located at the bottom of the power steering pump looking at it from the front the tensioner is on the bottom left. you could always loosen the alternator up a little. My 1997 with a 4.0 does not have a tensioner pulley, and I believe the 99s are the same. the alternator is the tensioner. Remove one of the bolts and it will swivel in and you can get the belt off
This applies to the L6 4.0L 2000 Jeep Wrangler. In the middle of the belt tensioner located below the alternator there is a 1/2 inch square hole. Insert the square end of a 1/2 inch breaker bar or socket wrench into the hole and turn the tensioner clockwise as far as it will go. The belt will easily slip of the idler below the tensioner. Not that the hole is between the bearings in the center of the tensioner arm. This is not documented in the Jeep service manual.
You cannot. It is automatically tensioned by the part that you describe. If it is out of adjustment, a new belt and tensioner is required.
15mm
mechanical
serpentine belt loose
There is a tensioner under the power steering pump. Lossen the pulley with a 15MM socket .. Do not remove it ... On top of the bracket to the left of the PS pump there is an adjustment screw again 15MM lossen it as well and the tensioner pulley will provide slack in the belt....once there is enough slack in the belt remove it make notes on how the belt is routed on the Alt,AC etc.... Replace with a new belt and tighten the adjustment screw until proper tension is on the belt then tighten the tensioner pulley below the PS pump. This is for a 98 Wrangler TJ...
There wasn't a Wrangler until the 1980's