LA145 grinding noise from PTO when brake released

[mmahoney626]

Greetings everyone, I have a John Deere LA145 that has run and mowed flawless since I acquired it. This week when I mowed, it has developed a strange condition I can't quite confirm the cause. I start the mower, brake pedal depressed. When I release the brake pedal, there is a noise coming from, as best I can tell, underneath the engine. When I depress the brake pedal, the noise goes away. The noise sounds very similar to when a blade spindle bearing is bad and the spindle needs to be replaced. The mower is not in motion, blades are not engaged. Based on the symptoms, my best guess is that there is an issue with the PTO, and I was going to replace. Can anyone confirm the diagnosis?
Thanks

 

[ILENGINE]

My educated guess is a bad bearing in the idler pulley on the drive belt to the transmission. That is how I diagnose problems with idler pulleys, just run then and listen for odd noises. Used to wiggle and turn the pulleys to check condition, but seems like the new pulleys have a bit of slop in them and in some cases new pulleys are worse.

 

[mmahoney626]

Would this be based on the symptom there is no noise when the brake pedal is depressed, but when I release the pedal the noise occurs? That's the part of my diagnosis I couldn't figure out, so I didn't want to replace the PTO if that wasn't the issue.

 

[Deleted member 97405]

When you press in the brake pedal, the linkage removes the tension on the transmission drive belt. That is why the noise stops! Because the belt and pulleys are no longer turning. Your PTO clutch is being turned directly by the crankshaft of the engine and is not related to your issue. (Usually when a bottom PTO bearing goes bad, you will hear the rough bearing when the clutch is off, and then the noise will go away when you engage the clutch because the bearing isn't turning when the clutch is on. If the top PTO bearing goes bad, you will hear it all the time because the top bearing spins whether the clutch is on or off.)
You have an idler pulley with a bad bearing on the transmission drive belt. I suggest replacing both if one is rough. (To change the pulleys, just set your parking brake. That will loosen the belt and allow you to swap out the pulleys and not have to fight with the belt tension spring.)

 

[mmahoney626]

Thank you both, this is great information so I am more educated, I will replace both pulleys.