hydraulic noise from gearbox

[redman135]

JD 6920 quad shift
About three working days ago I noticed a shushing sound from the gearbox (quad shift) under over run, ie let throttle off going into corner at road speed (40km/h) at first it was intermitant, but it rapidly (last 3 days) became much more frequent, but still intermitant.
There is no reduction in tractor perfomance. It is doing bale stacking and raking text book perfect.(southern hemisphere hay and silage season)
I just want to know what is going on. Can anyone help me?

 

[redman135]

Update: Mystery solved. The culprint was the muffler. On dec 31st evening the muffler came off.
The replacement muffler eliminated the hydraulic noise. The noise was air getting sucked into the exhaust on overrun through the cracked muffler flange.
JD parts did a good job of how NOT to do things. And we are not the only one , our dealer has a bunch of parts on order and no delivery. They are haveing to take parts of other tractors to get customers going.
This is southern hemisphere summer, read BUSY season.
Piss poor warehouse service is under mining the dealers good work.