When to Change Belt Tensioner and Pulleys?

Changed both last week at 350,000mi...after belt broke because of bad pulleys and belt tensioner

 

My fleet runs in a ruff, off road, and short haul conditions, we change the belts once a year (@100,000 mi), we’ve started using the Gates HD belt.
The belts made today are built so they don’t break, Dayco makes a go-no-go gauge for belts that works well to tell if it’s time. But it sucks waiting for the belts to tell you it’s time to replace them. Because it’s always either the hottest or coldest day of the year, and it’s always a spot that is the farthest away from the shop as possible!!!

We have also found that in our rough conditions that the OEM tensioner has been the cause for many of the belt failures. The Gates tensioner has served us better so far.

But if you’ve got 680k o your belts, what ever you’re doing is wiring and you shouldn’t mess with it!!!

 

I heard a guy on a maintenance program a few years back state that tensioners are designed to last the life of the belt.. according to him you should always change tensioner when belt needs replacement because it won’t last the life of the second belt..

 

I didn’t change mine till well over a million.Ran new one for around 700 k. Currently been running original one for a year.Aside from tensioner weakening causing belts to jump. As long as bearing is good it’s good. They can last a long time. Also can replace bearings if tensioner part is still good. If you’re worried about it going out best to buy a new one and keep on board along with spare belt ( new or old) just in case. Run it till it goes bad. Worse case it seized up and breaks belt.

 

The issue that we have is with the tensioner Detroit puts on their DD15. I’m sure it works well on highway. But we’re only on pavement 10-20% of the time. The small gravel from country roads gets sucked up and imbedded in the belts, this make the tensioner work harder than its ment to and the pivot point and spring/ shock absorbers lock up. And we throw the accessory drive belt, usually in the middle of nowhere!!

So in off highway applications, the Gates tensioner and belts are a better solution. Incase anyone is looking for the reason their DD15 is throwing belts randomly.

 

If you have any doubt about the tensioner and pulleys, remove the belt, spin the pulleys and tensioner and check for bearing play. All of those bearings are sealed, so no dirt can get in while the bearing is in good condition. If they are quiet and smooth, they should be good. If you change them just because of age, brand new bearings, right out of the box can fail. This is one of the MANY things that must be looked at on the pre and post trip inspection.

 

There is a tool to check tension I’ve heard of Somewhere. Seems a 1/2” torque wrench could be used to compare old against new