Mower deck Short deck belt life - poor idler pulley alignment

[Jim27]

I have a DYT4000 with 42" deck. Model 917.27364. It chews up a belt about every 2 months although 1 only lasted about 8 hours. It seems to be ripping parts out of the belt and breaking it rather than usual wear out. I run B94 gates belts. I had the belt jam in the electric clutch once but it usually breaks and doesn't jam so I can't tell what is actually happening. The last failure jammed between an idler and idler mounting. This is the idler on the left side of the deck and is poorly aligned with the other pulleys. The idler is above the spindle pulley so the belt rides on the lower lip of the idler. The bearing feels tight and smooth. I don't see anything out of place or worn that would let the idler move or tip. Nothing looks bent. I looked at the belt that has been on for about 10 hours and the bottom edge is smooth from riding against the lip of the idler. I thought the upper edge was getting rough but compared it to a new belt and it is the same.

I am pretty sure the misalignment is the issue but stumped on how it happened or how to fix it. I can post some pics if that helps.

 

[briggs]

I have a DYT4000 with 42" deck. Model 917.27364. It chews up a belt about every 2 months although 1 only lasted about 8 hours. It seems to be ripping parts out of the belt and breaking it rather than usual wear out. I run B94 gates belts. I had the belt jam in the electric clutch once but it usually breaks and doesn't jam so I can't tell what is actually happening. The last failure jammed between an idler and idler mounting. This is the idler on the left side of the deck and is poorly aligned with the other pulleys. The idler is above the spindle pulley so the belt rides on the lower lip of the idler. The bearing feels tight and smooth. I don't see anything out of place or worn that would let the idler move or tip. Nothing looks bent. I looked at the belt that has been on for about 10 hours and the bottom edge is smooth from riding against tche lip of the idler. I thought the upper edge was getting rough but compared it to a new belt and it is the same.

I am pretty sure the misalignment is the issue but stumped on how it happened or how to fix it. I can post some pics if that helps.

Check the bearings make sure there not seized up use the good belts made of cavlar rust well mess them up too

 

[Fish]

You are missing a digit out of your model number, please recheck it.

 

[Rivets]

Idler pulleys are very sensitive to bearing wear. They may seem to be good and tight, but a little wear can make a big difference. Also, check that the belt guides are in the proper position. Some guides are used to keep belts on pulleys, while others must be positioned to release the belt from the pulley. Guides not working properly or in the wrong position will snap or wear a belt fast.

 

[Jim27]

I did miss a digit of the model. It is 917.273640. The bearings are not loose or worn. The idler bearing has gone out before but the belt issue was virtually the same before and after the bearing replacement.

Here are some pictures.

The broken belt showing the chunks missing. Then the right side idler which is well aligned and the left side which is not. The metal bracket holding the idler has a slight offset in it but but is obviously made that way and not bent after manufacture. The last picture is the view of the right spindle pulley in the foreground, then the left idler, then the left spindle pulley - the idler being above the line of the other pulleys is obvious. The last one is from the opposite direction as the left idler pic.

I have noticed the belt gets quite warm.

I don't see anything bent or obviously out of place (such as spacers).

 

[Rivets]

If the belt is getting warm, I would still suspect an idler pulley bearing is worn. Remove each one and double check them. Here is where your finger tips become your eyes. Spin the pulley in your finger tips and feel for any wobble or jumping. Because of the speed they run, a little wear will amplify itself at full speed. Also, do you have any wobble when you install the pulley on it's axle?