When to Change Belt Tensioner and Pulleys?

Replacing a belt tensioner and pulley before it breaks and wipes out your belt and then the belt wipes out the air lines and other associated parts is considered cheap preventive maintenance.

If you have 500k or more on the OEM part, it's time to replace it, don't wait till it fails.

 

Check condition of belts for cracking, fraying. I had one fraying at about 500K km.

 

I just had belt come apart on 2017 Freightliner with 273,000 miles two front ribs ojn belt got eat up and belt come off. First they thought belt was bad but then said tensioner broke. Their is a new upgraded tensioner for Detroit. Freightliner parts guy said they been having trouble with the original ones go bad. Maybe it was just a bad one from factory but it new and improved now.

It was making squeaking sound as it was getting colder temps fall into winter. First it was only when engine was cold. Last two weeks it was squeaking all day and would change with engine RPMs. Started truck other morning and belt come off. They had to call road service guy. He had to drive 60 miles each way to Freightliner to get new belt tensioner.

 

New and improved belt tensioner on DD13 2017 Freightliner. So they claim anyway

 

I found that the accessory drive belt has to be changed annually. When you see all the things that powers, it is doing a lot of work.
Water pump, air conditioner, alternator.

 

What a few people may not think about is a blown belt at the wrong time (middle lane in stop and go traffic) now your choice is limp to the side and overheat badly because water pump on many engines isn’t turning or stop in lane and pay the tow.. a former co worker popped his head gasket on a new rebuild that he never changed belts and tensioner . Cummins didn’t honour the warranty after they saw temp the ecm recorded ...

 

They’ll usually start squeaking or ticking long before they seize up.

 

That's right- Newer trucks have belt driven water pumps- No thanks- I'll keep my gear driven.

There's a trick a mechanic showed me- Get yourself a Long screwdriver 24" and an empty 1 gallon jug-

Cut out the bottom of the jug- Place the Handle of the screwdriver in the top-(Make sure its a snug fit)

Place the end of the Screwdriver on the Bearing of each accessory pulley or tensioner if you start hearing a squeal......... The bad Bearing will come through Loud like a Megaphone,

But Be Careful where you stick the screwdriver- Carelessness will cause injury

 

I actually threw a belt today on my old 12.7 due to a bad bracket alignment. Put old chewed up belt back on.About every 6 mo I break 1 or 2 bolts. It’s been an ongoing ( common) problem on Detroit’s. I keep extra belts and tensioner. Time to shim it up and put new bolts again. Will repair front cover proper at next overhaul Belt only drives a/c and alt. Thrown them so many times. Never hurt a thing.

 

Much safer than putting ear up to screwdriver! I have a stethoscope now.Looks real important in toolbox Lol. Like the plastic jug idea. I’ll have to try that