Premature Hydraulic Belt Wear - Replace Tensioner

March 25, 2022, 03:43:58 pm

When I picked up my FT, one of the items that was replaced was the hydraulic belt by MOT. Since last summer, we've gone about 1800 miles so when I saw this premature wear occurring, I ordered a new Gates 38504 tensioner. I read on here that the alignment was also something to look at but since the tensioner had some vibration, I wanted to replace it. The original was a Dayco.

Upon closer inspection, the Dayco pulley was allowing the belt to sit 100% on it, causing the wear to occur on the end. You can see the size difference of the almost new one with the new one. After I replace the pulley along with a new belt, the pulley is now letting the belt sit on it completely. Time will tell but I am confident that this will fix this issue.

The 1st 4 photos are the old tensioner with bad belt, the last 2 are post install.

I got the tensioner at Zoro, and using 20% off coupon, it was cheaper than anywhere else. I would recommend subscribing to these emails as they do give user specific coupon codes out.

Re: Premature Hydraulic Belt Wear - Replace Tensioner

Reply #1 – March 25, 2022, 05:51:34 pm

Jason,

I had the same problem with our U300 hydraulic belt. Go back and look at my old posts. They have all the photos and instructions on how to align the pulleys. Bottom line is the tensioner is probably not bad and the chattering it's making is the belt moving back and forth on the idler pulley's flat face causing the belt's path to be shortened and lengthened a few times each second. . It's really simple to align the pulleys with only some hand tools and a magnetic angle indicator. The coach does not even have to be level.

If the pulleys have 8 grooves, the belt must have 8 grooves. I heard a lot of BS from others who thought 6 was enough so I called Gates engineering as well as Detroit Diesel. Once the pulleys are all in alignment, there will be no belt wear. You may need a spacer under the tensioner so the vertical alignment is OK. Ours was off 3 degrees. The flat part of the belt must be contacting the tensioner roller so it does not hang over the edges. It does not have to be exactly centered.

Ours was jumping quite a bit at idle but after alignment, it's smooth. When I had it off, I oiled the two bearings as they seemed a little dry. The Gates video is designed to sell tensioners and not to solve the real problem in many cases. Our OEM tensioner has 120,000 now and working just fine.

Pierce

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