John Deere 2355 hydraulic problems

[Windy Hills Farm]

We have a John Deere 2355 loader tractor and the hydraulics work good when you first start it up but as the tractor gets hot after about 1 to 2 hours of use they get slower and slower until you can hardly use them. it has been like this for awhile but last time I used it the power steering started chattering for the first time. When you open the hydraulic fill cap, you can hear a hissing sound and there is lots of hydraulic vapor coming out. I do not know if this is a related problem, but when you try to hover the 3pt hitch between all the way up or all the way down, the loader and the remotes do not work well even when the tractor is first started up.

Does anyone know what is wrong?

 

[Tx Jim]

Welcome to this forum
Yes hydraulic noises & vapor being emitted from hyd filler hole behind seat indicates that rockshaft control valve seals are leaking & need to be replaced. Rockshaft housing must be removed to replace those seals. What type valve controls front end loader(independent or scv)? How many hrs of use since hyd filter was changed & hyd oil suction screen checked/cleaned?