GC1705 Mid Mount Mower Noise

[Massey2019]

I have a 2018/2019 GC1705 with the 54" mid mount mower deck. For a tractor, it does a nice job of mowing. Nothing out of line, even cuts.
My issue is a strange buzzing/screaching noise that happens occasionally. It is loud enough to catch attention of others outside my yard.
It has occurred since I got it. Called the dealer a couple of times and no suggestions on what could be causing it. Only happens every couple of minutes.

Here is what I have done and checked.
1. All bolts are tight and I checked the torques based on sizes.
2. Gearbox is smooth and has no leaks or drips.
3. Greased all fittings multiple times and they all take grease.
4. Made sure belt tensioner moves freely.
5. Put weather stripping on the bottom of both belt covers to make sure they weren't vibrating.
6. Flipped over and checked blades to make sure nothing is hitting.
7. PTO shaft moves smoothly and is greased multiple times like the blade spindles.

The only thing I can see is the belt tensioner pulley has the coating worn off in a couple of places where the belt contacts it. It is not worn all the way around the OD. It seems to turn OK. The belt is slightly shiny on about 40% of the flat face.

I'm wondering if the belt tensioner pulley was maybe not manufactured correctly and gives me this noise due to loading or angles?

Appreciate any suggestions.

 

[JWR]

I assume you are sure it is the mower deck? Not an engine fan belt or other engine related noise?

How often do you have it screeching? Is this a new deck or orig one that came with the tractor ? Does it affect the noise as to how fast your engine is running/rpm? When it makes the noise how long does the noise last ? Long enough to run the rpm a bit lower or higher to see if it changes?

My first guess is someone got grease or oil on the belt. I would inspect it very closely by removing the covers and manually pulling the belt through slowly for the whole length of the belt. The contact surfaces of the belt would be the only ones that matter, though there may be tell-tale signs of grease on the back of the belt too. The slightest bit of grease/oil on that belt will cause slippage on the drive pulley and I have seen belts burnt up that way. A gas soaked rag or some solvent that totally evaporates would be the way to go if you find grease on the belt. Any sign of damage to the belt?

Second guess is the bearings in the tensioner pulley. If not the belts slipping it is probably those bearings. I don't know if that is a sealed bearing with no grease fitting (probably so.) If there's no way to lube it I don't know how to check it short of replacing it. I'd do a lot of investigating before doing that. You might be able to take the belt off of the tensioner and see if the tensioner pully spins freely and quietly or wobbles -- e.g. looking for bearing issues.

Keep talking to us ! And good luck.

 

[seville009]

I didn't see it in your list of things you did, so try a new belt.

worst case is that you end up with a spare belt, which you'll need at some point anyway.

belts can slowly stretch over time. Even just a tiny bit will affect it.

 

[irvingj]

Agree with JWR above (nicely put, BTW!). Grease on belt or bad bearing in idler.

 

[Massey2019]

Well, spent quality time going over every piece of the deck today. Rechecked all bolts, brackets, covers, etc. Looked for interference or rubbing.

Took tension off the belt and think I found what the issue is. The nut on the inside of the bracket that locks the adjustment screw/bolt was backed off a couple of threads. So, the belt tension was right, 5.08-5.16", but I think this was the source of the noise, with the clearance. The tension pulley is smooth and stable.

Belt didn't have grease or oil on it but was sort of dirty. Would assume this is from wear and dust from mowing. Wiped it off and didn't find any strange wear.

Put all back together and went out and tried mowing. Various bumps and dips in the yard, raised and lowered, forward and backwards at different speeds, different mowing heights and no noise!

So, my guess is that the small amount that the tension rod could move allowed it to vibrate and that went back into the spring and pulley.

I appreciate the suggestions and help and it goes to show I should have been much more focused on details that I originally was.
Thanks,