Belt coming off Joh Deere 272 grooming mower

Jamez2u · May 19, 2020

I use the 272 mower behind my JD 770 23hp tractor to cut down the weeds. But this year while cutting down the weeds I heard a noise and the mower was making more noise than it normally does I took off the belt cover see if I broke a belt but the belt is still in one piece but riding on the edge of the pulley instead of inside the grove of the pulley. What could be causing this? when I disconnect the mower from the PTO and spin the shaft by hand the belt falls back into the grove of the pulley but when hook back up to the tractor the belt immediately works its way back out to the edge of the pulley and of coarse does not turn the blade very well.

K5lwq · May 19, 2020

Two things I would consider.

1. New belt

2. Check the idler pulleys to insure bearings are good. Sometimes this will cause a belt to not ride properly on the drive pulleys.

Industrial Toys · May 19, 2020

Be very carefull. An old 60" JD belly mower I owned on a 770 tractor had these EVIL formed mild steel claws on the underside of the pulleys that would shread an errant belt. Maybe designed to shed debris. Maybe?

kthompson · May 22, 2020

I would lay where I could see the belt and pullies from the side and see if I could see a pully that is tilted. Would remove the belt totally and turn each pulley including the blades by hand to see if it turns freely and if there is any wiggle in it where it could tilt with load. Look for loose bolt holding the tension pulley arm to the deck.

Wyobuckaroo · May 22, 2020

Bad bearings in idler pulley. It may not look bad, or feel bad when turned by hand, but at speed it is different..
Not enough tension on idler pulley.
Not a great belt, but not a wore out belt..

All this giving the idler pulley a chance to bounce just enough to release tension on the belt just enough to be a problem. On my mmm deck all it took was half a screen door spring to make the little extra tension to keep all working well... It worked well until the bearing finely went out on the idler pulley.. Replaced idler, all was well with out extra tension again..

chim · May 22, 2020

The surface of the pulley where the belt rides looks rough in the picture. Regardless of anything else, I'd want to clean it up if that's the case so it doesn't tear the belt up.

Jamez2u · Jun 6, 2020

An update, I purchased a new belt for like $30 bucks and before installation made sure it was the same size as the old belt. It was a little bit smaller, which I expected because the old belt had been on there since I purchased the mower so it was a little stretched out. After I got the new belt on it was incredible loose I did not even try starting up the tractor/mower as I new that loose it would come off. I was confused as this belt was smaller than old one and still loose. I search everywhere online and every manual I could find nothing. I was almost read to make so modifications to the mower to adjust the tension spring but then I called my father. He has the same tractor but he lives further in the mountains than me we spoke on the phone and verified I had the belt on the correct way according to diagrams I found online and the sun bleached diagram that was hard to see on the mower itself. He told me that there must be something underneath the deck to adjust the tension spring. So using a ***-along I lifted the mower. There was nothing on the bottom of the deck and nothing of the top of the deck but on the back of the deck was a rusty old bolt with a nut on it. I sprayed some PB blaster penetrating oil on the bold and turned it counter clock wise as I looked at the mower to see what it might be for. OMG it was moving the tension spring. The same spring I read else where online that said this was non-adjustable. I put the belt back on and moved the nut all the way out, the belt was now felt like it was at the proper tension. I jumped on the tractor, started her up and engaged the PTO the mower ran and the belt stayed where it should. After a few weeks of waiting for the belt and doing research both on and offline I found the simple fix to get my mower running again. I was able to mow the yard before cal-fire came out and gave me a violation for grass being too high and put my tractor away to wait for the next project on my little piece of dirt I call my own. I hope this helps someone down the line if they have a John Deere 227 mower that starts to throw belts.