I have a husqvarna riding mower with a hydro transmission and a 15hp kohler engine. When I first run the mower it's fine, over time (about 20mins) it starts to run slower and slower. After 20 mins in forward it goes very slowly and not up inclines, in reverse it won't go at all (unless I hop off than it goes slowly). I replaced the belt and confirmed the spindle is spinning on the transmission. I can hear it straining when in gear. Is there anything I can check? Any thoughts on what the problem could be or a remedy?

Thanks,

Matt

i had a older cub cadet with a hydro transmission with almost the same thing going on all i had to do was dump all the transmission fluid new filter and refill it was like new again the tech at cub told me my oil and filter were very old the fluid thins as it gets hot and old fluid does not hold its properties and the pump was unable to push it but in my case this easy fix worked for me

hope it helps