are you checking correct oil? power steering oil, engine oil, transmission / rear end oil (some times separate), along with general hydraulic oil that runs 3pt hitch / FEL (front end loader) is in yet another location. *been there done that *arghs**
i suppose a seal might of gone bad. and pulling air into the power steering system. (not a clue about your specific tractor and how it is setup)
any oil leaks any place?
are you turning the wheels to far (and hitting the lock out point, i forget correct term) and relief / check valves are kicking in?
when you say cavitate... how do you know it is cavitating? do you hear like rocks being grounded up in a grinder (kitchen grinder normally for foods), or do you hear a clicking sound?
what does the oil look like? ((look at it before starting up tractor for the day)), then run it a little bit and get it to "cavitate" your words and then look back at the oil. does it look milky (lots and lots of tiny little air bubbles in oil, causing oil to look different aka milky)
do you have a FEL (front end loader) on tractor and loading things down pretty good?
or perhaps getting front wheels in ruts and trying to turn wheels up and out of ruts?
how does the steering wheel respond. if you go and turn it left, does it immediatly begin turning left ((assumption tractor is going forward)), if you turn steering wheel right do tires immediately turn right? or is there a slight delay?
((adding one more question to above)) does situation get worse more you drive. say initially starting up tractor all is ok, then over course of say a few minutes to a couple hours things get worse. or are things worse initially starting up tractor. and after i don't know say 5 to 30 minutes of running things get better after having a chance to warm up?
there is most likely an "intake screen" some were near steering pump or perhaps directly in the pump. maybe there is an actual steering wheel filter some place, but going to guess most likely a little screen. (something like what your faucets in kitchen sink / bathroom sink have). double check that it is not clogged up.
have you taken a wrench and double check everything is tight? stuff happens and stuff comes loose.
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a shop manual most likely gives a full break down of all parts and diagrams + instructions to tear stuff apart and put it back together, checking stuff along the way.
a parts manual = very ugly diagrams, just enough to identify / show a part, if your half way mechanically inclined it might help you. it has been some time since going to kubota website, you might find a parts listing for your tractor, to help track stuff down.
Home | Messick's i want to say has online part listings for kubota as well. i may be wrong.
user manual = very simple info.
