Dixie chopper whining noise

[Therapydoc]

Just bought a XT 3300 with a 33 hp Generac motor. Motor makes a winding noise anytime throttle is above 25%. First I figured it would be hydraulics however when I listen closely it’s almost positive coming from the engine. Previous owner said it’s been there over 2 years and never had any issues. Was an older gentlemen so I believe him. There’s no other symptoms. Hydraulics respond well both sides and motor runs strong also and I don’t hear any knocks or anything. He replaced engine oil and hydraulic oil end of last year. He did use Walmart brand 15w40 so I plan to drain and put rotella 15w40 in. He put new spark plugs on it but when I pulled the wires, they are rusty and old so I’m replacing them (any particular wires to use ?). Anything else I should check ? Local mechanic said could possibly be air getting into fuel system but I sprayed carb cleaner along most of the lines and didn’t see anything and motor didn’t bog down any. Worst case scenario, I wear my muffs and live with it but I’d rather fix it if something is wrong.

 

[mechanic mark]

https://www.dixiechopper.com/2/manuals&cat1=11&cat2=333

DIXIE CHOPPER XT3300 GENERAC MAKING WHINING NOISE - Google Search

 

[bertsmobile1]

First thing to do is pull the drive belts off , both deck & drive.
Start the engine & throttle up.
Whine goes away then refit the drive belt.
Whine comes back check the tensioning pulley and the fans on top of the pump(s) .

If it is in the engine then pull the blower housing off and start it again so you can hear where it is coming from.
Very few people actually pull the blower housing off & clean out the fins and fewer still pull the flywheel and clean the build up off the magnets.