I just bought a 2013 Kubota
M6040 hydraulic shuttle and it is making the same clunking sound at idle. Did you ever find out what was causing yours. Just brought my tractor to the dealer no word from them yet.
I HAVE CLOSE TO A THOUSAND HOURS .... NO PROBLEMS AT ALL .... I DON'T EVEN NOTICE THE NOISE ANYMORE ... FORGET TO LISTEN ....
MY DEALER CHECKED EVERYTHING - THEN HAD KUBOTA'S TECKS CHECK EVERYTHING .....
HE THEN WENT TO ANOTHER DEALER - AND THIS DEALERS
M6040 MADE THE SAME SOUND .... HE THEN ORDER ANOTHER NEW ONE FOR HIS DEALERSHIP AND IT MADE THE SAME NOISE ! I WENT THERE AND HEARD IT.
SO, AS BEST I CAN SURMISE ... IT IS THERE, BUT IT IS NOT A PROBLEM.