Why does my riding mower lose 'drive power' after 15 minutes

[mistermerp]

I have a Scotts by John Deere 2046 riding mower (about 20 years old). The mower starts fine and runs well for 10 minutes. But then gradually starts to slow down and after a few more minutes of cutting, it just won't move. To be clear, the engine is still loud and running strong. However, the mower starts going slower and slower until it just won't move forward.
So, I thougth it might be a worn drive belt - so I changed the drive belt. Is there a chance it's too tight or too loose?
Can you think of anything else this could be?
Thank you - Matt

 

[tom3]

You have a "non serviceable" Tuff Torq transaxle that probably needs service. Pretty common with this unit that was built as a throwaway but can usually be made to work for a while longer. Might check on Youtube for a K46 or K51 Tuff Torq video or read this:

K51A Transaxle Fluid Change

www.mylawnmowerforum.com

 

[bertsmobile1]

Tom is probably on the money.
However check the drive belt & pulleys.
Those trannies have a life of around 500 hours depending upon how much they get abused & manufacturing tollerances .
You can pull them off , open the fill port on the top, drain all of the oil out and refill with 20w50 synthetic engine oil .
o\If it is not worn too bad then that can stretch another few years out of it .
One I did better than 4 years ago is still going strong although a bit noisy, but the owners is deaf as a post so she does not care.
Others have barely lasted a season.
Replacing the transmission is a simple job allow about 2 hours each way if you have never done it before.
Take lots of photos .
Mulligans are my go to for transmissions, best prices and best service by a long shot.
Honest people who don't feed you crap to make a big sale.