520 H -96 Pulley Noise

[jamessparks 55]

Question on the pulley for my 1996 520-h horse (73501). All original, no modifications. 
 

The pulley in front of the hydro fan is “clanking” to the top of the belt guard cover?  I looked on my manual and couldn’t even find a diagram or part number. It has a spring also attached. 
 

Any thoughts or ideas?  I’m going to pull the cover tomorrow but just wanted to inquire. 

[Cee245 818]

That looks like the drive idler pulley.  It's a fairly easy fix.  Ive replaced them a few times. Normal maintenance item.

 

Good luck!

[Handy Don 12,457]

I suspect one of two candidates:

1. the idler pulley bouncing up against the top of the drive belt cover, or

2. the pivot shaft that holds the pulley is worn and rattling

 

Getting the belt cover off is the way to see what's happening (just be careful once that cover is off and keep safely away from the moving parts!)

 

#1

- Wear on the drive belt so that it doesn't go around the pulleys smoothly and the idler "bounces" excessively -- causes are broken cords or worn sidewalls (sighting along the top of the belt with an inspection mirror to look for kinks in the belt as it goes between the pulleys is helpful). Some bounce is normal. Absent causes of premature failure, drive belts should last a long time--I have a 700-hour belt of mid-90's vintage that is doing just fine.

- Less likely is a weakened spring -- usually this is from extensive rust or corrosion which don't seem evident in your picture

- Also less likely is that the idler pulley's sealed bearings are shot (the pulley will seem loose on its hub)

- I'm discounting the other option where you've put on a new belt that is too short!

 

#2

- Wear on the ½" shaft that holds the idler arm and pulley. It traverses the tractor so the other end is under the left side cover. The tensioning spring attaches to an arm on this shaft. To check it, you have to detach the tensioning spring and test for lateral movement in the shaft. Anything more than barely perceptible is enough to cause noise.

 

Let us know what you find. Include pictures!

Edited April 20, 2021 by Handy Don

[gwest_ca-(File Mod) 11,095]

https://www.partstree.com/models/73502-520-h-toro-garden-tractor-sn-069000001-069999999-1996/hydro-drive-26/

 

Garry

[Ed Kennell 38,634]

Looks like Don has everything covered James.    Does that model have the idler disconnect lever?

[jamessparks 55]

Thank you Don, Ed and Garry. I’ll pull the belt guard tomorrow and get a better photo and description of what is occurring. Crazy this evening I finished mowing with my 416-H and heard a similar noise and noticed almost the exact same with it. Same pulley and movement. 

[jamessparks 55]

@Handy Don looks like a little wear at spot #2 where you mentioned about the shaft. I believe there is a bushing there and it is kind of loose in that area. The pulley itself looks great and no movement at all. 

[seuadr 488]

so i recently replaced my drive belt and this thread got me thinking - how much belt tension should i have? i'd guess i have somewhere around 3/4 to an inch of play when i squeeze it - it doesn't make a noise like it is flopping around and as far as i can tell the machine responds nicely to movement input controls, but now i'm not sure?

 

[Ed Kennell 38,634]

James, looking at the spring in your pic, it appears the spring has very little tension.    I recently replaced the drive belt on my 312H and found the factory length belt was too long.  I used a 1/2" shorter belt. 

This raised the idler pulley about 1/2" increasing the tension on the spring.   I buy several length  TSC belts, then return the ones I don't use.

[Handy Don 12,457]

3 hours ago, jamessparks said:

@Handy Don looks like a little wear at spot #2 where you mentioned about the shaft. I believe there is a bushing there and it is kind of loose in that area. The pulley itself looks great and no movement at all. 

 

Close in I see what looks like a cracked frame just above the idler shaft. I'm hoping that's just some debris or scratches. The part of the belt visible in the image doesn't have any unusual wear. Understand that the movement may not be on the pulley side--it may be at the OTHER end of the shaft. @Ed Kennell's point on belt length and spring tension is valid, though yours seems ok from here in this static image.

 

There is a very unusual flanged bronze bushing on the drive pulley side (½" ID, 9/16" OD, ½" L) but on the other side there is no bushing, just an E-clip and thin washer to hold the shaft in place. This means the frame holes are different diameters! On the pulley side, 9/16" and on the other side ½". Sigh. Also, the holes in the frame are not just drilled--they are flared inward so that the bearing surface of the hole is twice as deep as the thickness of the metal frame wall as you can see from the wear patterns in the images below.

Pulley Side:  

 

Offside:        

 

My experience was that the bushing didn't wear appreciably but the shaft itself did--and more at the end away from the pulley without the bushing (see images below). Ugh. This spot deserves regular lubrication but it extremely hard to access for most folks.

 

I was able to source a replacement shaft with hardly noticeable wear off a parts tractor (it was from a drive clutch version and I had to drill/tap a new hole in the arm for mounting the pulley). I also reamed out the off-side frame hole to 9/16" and used the extra bushing from the pulley side of the parts tractor on the off side of my tractor so it's no longer "stock". I had to substitute a slightly thinner washer on the pulley side between the arm and the frame to account for the extra thickness of the added bushing's flange. This moved the pulley closer to the frame by about 1/16" but it hasn't seemed to matter. I carefully cleaned and then thinly coated the moving parts with a good lithium grease (Red n Tacky) when I reassembled things.

 

This was not a simple repair. All in it took several hours of thinking, working, and muttering stuff (I'm a very deliberate worker). I concluded that other than the noise it was making, there was probably no immediate danger to the tractor or the operator so it's really up to your tolerance, ambition, and skillset to work out what to do!

 

Good luck.

Edited April 21, 2021 by Handy Don

[Handy Don 12,457]

@jamessparks please let us know what you found and what you did about it (with pics of course )

[Jeff-C175 7,203]

On 4/21/2021 at 11:27 AM, Handy Don said:

looks like a cracked frame just above the idler shaft

 

Talking about this Don?  It does look like a crack but I bet it's not... probably just a dirt smudge or grease... or ?

 

 

Belt does show a little wear though, and some cracking.  Not too early to replace it IMO.

 

 

 

Also, BTW, the idler on my 175 has been 'rattling' for about 30 years.  SOMEWHERE, some time ago, I read something about an 'anti-rattle spring' but I can't find it now.  I never did add it after I read that.  If I put my hand on the lever it stops.  Not going to worry about it, I consider it 'normal'.  Now that I've got the deck rebuilt I'm sure I'm going to hear a lot more noises because the deck is nearly SILENT!  I know... I'll just turn up the radio! 

 

 

 

Edited April 22, 2021 by Jeff-C175

[Handy Don 12,457]

18 minutes ago, Jeff-C175 said:

Talking about this Don?  It does look like a crack but I bet it's not... probably just a dirt smudge or grease... or ?

Belt does show a little wear though, and some cracking.  Not too early to replace it IMO.

Also, BTW, the idler on my 175 has been 'rattling' for about 30 years.  SOMEWHERE, some time ago, I read something about an 'anti-rattle spring' but I can't find it now.

Yeah, that was it. A crack in that location doesn't make any sense, though, without a break in the frame right below it and the other images didn't indicate that.

You are right, too, that replacing the drive belt wouldn't hurt. I was more on the "this isn't likely the cause of the rattle" theme.

 

I considered adding a spring to the other end of the shaft as an "anti rattle" and in the argument-with-self the "you've got it all apart now, just fix it and be done with it" won. If I'd known then what I know now, however, I'd have just let it rattle--that's why I wanted @jamessparks to have info for his own decision. Note that the later 520's (including mine) don't have the drive clutch.

 

BTW, the most annoying part of this was getting the roll pin out of the parking brake knob sticking out of the left side cover!

Edited April 22, 2021 by Handy Don

[jamessparks 55]

@Handy Don it was just I didn’t clean it well enough for the photo. Just dirt! 
But for sure, you had me thinking and worried so back to the garage and off with the belt guard to double check. Thank you again for all the insight and feedback. I did order a new drive belt and tension spring and they should be here next week. You are correct though on that left side panel as I just replaced two hydraulic lines on my 416-H and that roll pin/brake lever combo is a bear. Haha. Thanks again and I’ll let you know next week how progress is. 

[jamessparks 55]

@Handy Don @Ed Kennell got me a new spring for the idler pulley and that fixed the vibration. My pulley bearing is good and thank you both for your insight and help. 

[Handy Don 12,457]

20 hours ago, jamessparks said:

@Handy Don @Ed Kennell got me a new spring for the idler pulley and that fixed the vibration. My pulley bearing is good and thank you both for your insight and help. 

We love hearing back on outcomes and especially when they are good ones!  Hope you get a lot of work and enjoyment from your machine.