Using a belt tension gauge

[Bonnewagon]

I just scored a set of three Kent-Moore belt tension gauges on Ebay. One is for old school V-belts like on our cars and my Pontiac manual calls for this exact tool. The V-belt type one has the instruction on the back and is self explanatory. One is for a timing belt, and the last I think is for an adjustable serpentine belt. My Kent-Moore catalog says they are really for the Quad4 motor, but should be good for any adjustable serpentine belt. But how does the serpentine one work? I see how the dial turns as you push in the ball. Does the belt go inside the jaws, outside, do you press for tension or does the spring do it,or what? It is a Kent-Moore J-36018.

 

[Bonnewagon]

I think I figured it out. You press the ball on top and extend the jaws all the way open. Then you insert the belt into the jaws. When you relax the ball, the belt is caught between the jaws and the internal spring pressure of the tool measures the belt tension. I tested the calibration by inserting a filet knife in the jaws and it tested perfect- 135lbs. And that is how I fixed the other one which appeared broken. What is was, was the internal gear that spun the dial was stuck. There is a spring holding the gears together and one over rode the other, making a clashing sound. I freed it up and oiled it now it works like it should. Since I had to remove the dial scale I needed to return the dial to where it needed to be, so I again inserted the filet knife between the jaws and when it came to rest I replaced the dial so "calibrate" was indicated. Just to be sure I looked closely at other gauges on Ebay and saw that the dial was in the same position in the resting state. Great, now I have three kinds of Kent-Moore belt testing gauges that work.

 

[Bonnewagon]

So I used the gauge on a Jeep 4.0 and the tension was only 40lbs. Makes sense as I only tightened it by hand until any squealing stopped with lights, AC, power steering all on. I increased the tension to 80 lbs which is still only half the books spec but should be plenty. I am scared stiff I will ruin components again. Then I tested a 2010 GMC Sierra 5.3 truck that is making loud belt noises. It has an automatic tensioner but the belt only tested at 50 lbs. I'm guessing the tensioner is weak but we can't seem to find a spec for the tensioner or the belt. Any one know?

 

[pontiacgp]

I could not find any info on how that tool works. Doesn't the tension pulley have markings on it or an indicator to so show it's giving proper tension.

 

[Bonnewagon]

Not that I could see. I will check again. But I also cannot find any spec anywhere for any serpentine type belt. All I can find is generalities, like rusty, noisy, broken tensioners. . I am about to go visit a shop with ALLDATA and maybe they know. I have a feeling the procedure is- replace everything and hope for the best.

 

[pontiacgp]

on my serpentine set up the tensioner has a pointer on it and it has to sit in between 2 markings

 

[Bonnewagon]

I went to look it up in ALLDATA. It said to put a torque wrench on the tensioner bolt and take a reading. Then - are you ready?- it says to compare that reading to a known good one. WOW! Why didn't I think of that! I will go buy a new one and install it just to compare the reading to the old one. Brilliant!

 

[pontiacgp]

That is a good idea but it would be nice if they put in a range that the belt would be good