Belt Problem, John Deere D170 54 inch deck

[bear15]

We have a John Deere D170 with 54 inch deck and 234 hours on it. When the grass is taller/thicker the belt comes off and needs to be put back on which is a pain. Does anyone know if there is a way to adjust the belt tension or a fix to this problem?

The spring looks great, pulleys look fine (no wobble), I do not notice any issues. I put a new OEM belt on and I have the same problem.

Any help appreciated.

 

[beenthere]

:welcome: to TBN

There is an issue there, so only advice would be to keep looking.
Sorry can't be of more help, as you seem to have checked on the obvious.

Someone will surely be along who will have more ideas.

Anything major happen that you can think of when this first started?

 

[bear15]

No, not that I can think of.

 

[bear15]

Any ideas?

No, not that I can think of.

 

[Richard001]

:welcome: to TBN

There is an issue there, so only advice would be to keep looking.
Sorry can't be of more help, as you seem to have checked on the obvious.

Someone will surely be along who will have more ideas.

Anything major happen that you can think of when this first started?

So are you saying that up until now, you have not had this belt issue and it just started this year?

Richard

 

[beenthere]

Are either of the three deck spindles hot to the touch when the belt is thrown?

 

[tomplum]

Which of the pulleys does the belt seem to come off? Perchance is the deck pitched greatly forward?

 

[bear15]

Not any hotter than normal.

Are either of the three deck spindles hot to the touch when the belt is thrown?

 

[bear15]

It is always off the center pulley when the belt comes off. Regarding the pitch, the deck appears to be level with the ground.

Which of the pulleys does the belt seem to come off? Perchance is the deck pitched greatly forward?

 

[Captain Dirty]

We have a John Deere D170 with 54 inch deck and 234 hours on it. When the grass is taller/thicker the belt comes off and needs to be put back on which is a pain. Does anyone know if there is a way to adjust the belt tension or a fix to this problem?
The spring looks great, pulleys look fine (no wobble), I do not notice any issues. I put a new OEM belt on and I have the same problem.
Any help appreciated.

On a JD front mower idler pulley I had no wobble from pulley to its shaft but wobble of the shaft relative to the plane of the belt owing to the "buckling" or "oil-canning" of the stamped, sheet metal deck itself. The heavier load of tall, thick grass may be causing your deck to buckle. I welded some stiffening flat stock to the underside of the deck, and that solved the problem.

 

[bear15]

Interesting . . . do you happen to have a pic of your weld job??

On a JD front mower idler pulley I had no wobble from pulley to its shaft but wobble of the shaft relative to the plane of the belt owing to the "buckling" or "oil-canning" of the stamped, sheet metal deck itself. The heavier load of tall, thick grass may be causing your deck to buckle. I welded some stiffening flat stock to the underside of the deck, and that solved the problem.

 

[Captain Dirty]

Interesting . . . do you happen to have a pic of your weld job??

Regretably, not readily available. Removing the deck is a bit of a chore, and displaying my welding beads on a forum that includes Shield Arc is embarrassing. My major decision was to lay the flat stock flat on the deck rather than the more effectively stiffening on edge, rationalizing that on edge might affect the air flow under the deck. It was probably 1/8 or 3/16" thick. I think I was compensating for wear (erosion) by sands and dust. The direction of the stiffener was in line with the force resultant from tension on the belt. [Is that 1000 words yet?]

 

[bear15]

Got it.

Regretably, not readily available. Removing the deck is a bit of a chore, and displaying my welding beads on a forum that includes Shield Arc is embarrassing. My major decision was to lay the flat stock flat on the deck rather than the more effectively stiffening on edge, rationalizing that on edge might affect the air flow under the deck. It was probably 1/8 or 3/16" thick. I think I was compensating for wear (erosion) by sands and dust. The direction of the stiffener was in line with the force resultant from tension on the belt. [Is that 1000 words yet?]

 

[bear15]

Thanks for ALL the help. I completed the following and it seemed to fix the belt throwing problem.
-replaced all 3 spindles and greased
-replaced all 3 idler wheels
-replaced all 3 blades
-tightened the idler plate 3/4 of a turn
-set the front of the deck 1/2" higher than the back
-set the cutting depth 1 notch below 3
-kept in idle speed when engaging blades
-cleaned all debris from deck area
-replaced the belt with new OEM

 

[beenthere]

Turn the nut (C) on the front draft arm counterclockwise 1-2 full turns so that the front of the deck is 3-6 mm (1/8-1/4 in.) lower than the rear. This adjustment prevents “double cutting,” which wastes horsepower and causes brown grass tips.

This is according to your operators manual.. and you did the opposite by about 3/4" which may be a problem.

 

[bear15]

I know . . . this has been a nightmare. We have really had to think outside the box on this one.

This is according to your operators manual.. and you did the opposite by about 3/4" which may be a problem.

 

[jeffcarpenter]

Is that repair still working? I ask because I bought a new E 170 this summer with the 48" deck on it. It was actually one that had been returned to Lowe's because somebody had left the owners manual on top of the engine, and it had caught fire. The damage from that had been repaired, so I bought it with 4 hours on it for over $1,000.00 off of the new price. Well, I'm having the same issue with the belt.

Right now it's got 34 hours on it, I've put two new belts on it, and had to put the belt back on several times. I was mowing some heavier grass last night, but it has thrown the belt off before with no warning for no reason that I could see. And it chews the belts up. I explained to my wife and son to start the blade at an idle, and that has helped make the belts last longer. The belt that is on it right now is still in fine shape. They are the K-force belts, they say they are the OEM belt.

At any rate, this morning I took a closer look at the pulleys. The tension pulley has quite a bit of play in it, both in the tension arm connection, and in the bearing itself. So, that might just be the problem. Also, I did not consider the deck pitch. I'll take a closer look at that. My Dad works for John Deere and I've asked him to look into the problem, but he hasn't gotten back with me, and as we moved two states away this summer, he has never seen the mower.

Thanks,
Jeff Carpenter

 

[tomplum]

K-force belts make the belt to what they believe are the OEM size, but it may not be correct. Use the GX21395 belt from Deere. Sometimes the bearing in the idler is loose in the bore. When you go to replace the pulley, have the serial number ready as there is a serial number break. Seeing as though this was return, pull the deck to clean and check the blade installation, do the pulleys run true etc. Guards should be installed and check the deck pitch when reinstalled. Excessive pitch can lead to walking the belt. One tip to help extend belt life when you have a longer belt with lots going on is to condition the belt. In this case condition means to run the deck in a no load or very light load for 15 minutes. This helps the belt find its spot in the pulleys.