Am looking at a Hitachi uh171 to purchase. Problem with this machine is that the hydraulics do nothing. Previous owner has removed and plugged two of the large pumps and states that the machine worked fine with this modification. I have no pressure out of the large pumps and must believe that there is a control sytem pressure problem. There is a small pressure pump to the one side that seems to be for the control circuits, but as the owner has no service manual showing the hydraulic circuits, I am at a loss to go further with diagnostics. If anyone has a manual with info (or idea) to repair this problem (or to bypass) please reply. I am very interested in this machine as the price is right, if I can load on trailer, but as the arm is fully extended and the unit does not move it would be very hard to bring home.
if you really want this machine...rent a portable hydraulic pump & make up a couple hoses. you could use another machines hydraulics, but then you're taking a chance of contaminating its hyd. system
pay a good mechanic a coupla hundred...have him give you an assessment of the machine, will pay off in the long run...might be a good buy, might be more headache than what it's really worth, you know what they says....oats can be bought a lot cheaper once they've gone through the horse.
Could it be more of a electronic problem (or linkage, depending on the year) than a hydraulic pump problem?? Perhaps the pump are not getting the signals to pump.
A UH machine is pretty old I wouldn't even consider it if your looking at Hitachi machines try buy a EX machine. Keep searching you will find a better machine if your not getting that UH machine for anything more than 7000 grand CND walk away.
UH171 Repair I now own this old machine. These are the steps I took to repair the hydraulic problems. First I found out that JOHN DEERE now has the repair manuals on their website for download, so I did this. With this information,following the hydraulic circuit, I checked pressure on the pilot pump to see if it was reacting to the lever actions (main valves controlled by hydraulic pilot). The pressure was a little low, so I adjusted to spec by adjustment to pressure regulator. No improvement. Took pressure reading from main pumps and found both to be very (200psi) low. I removed both axial piston pumps (kawasaki 925) and disassembled. I found that the fixer plates had broken away from the sway plate therefor causing no piston displacement. (The low pressures recorded earlier were from the small pilot pump that is also used to prime the main pumps) I replaced all pistons, fixer plates, bearing and seals on both pumps (850.00CAD) and reinstalled on machine. Now machine functions correctly with pressures up to 3500 psi. The two aux pumps missing on the machine , provide an additional 50 litres per minute flow, but I will try to find used ones at a later date to increase the speed (approx 22% , if I calculate correctly) Overall, this has been a simple repair, once I had the manual, and the sytems on these older machines are very easy to follow. If I can help anyone out with a repair question on a UH171, please do not hesitate to email [email protected] PS: Thank you to all who replied.