Hello, I've recently aquired a 1985 Hitachi UH07-7 which is about a 200 size machine. It has 13,000 hours but I got it from a family member so I know that its been maintained well and what the history of it is. It has an issue with the hydraulics, they work perfect fine for quite a while, anywhere from 1-3 hours depending on how hard its been run. After that point I lose all responsiveness in my controls. It will sometimes take up to a second or two to get any response and it gets extremely hard to operate. Working it hard makes the problem happen faster whereas I can do light work indefinitely. In general, the hydraulics on the machine are very good. The change from working completely perfectly to having major issues is drastic and sudden. On a side note, does anyone know where to find the serial number on this machine? The plate with all that information is long gone and I'd like to know a secondary location. Thanks, Bob
If you have pilot controls on this machine keep a guage on your pilot pressure before your sticks. If it had mechanical controls I would say the pressure compensator in the pump has a bad seal
The pilot pump has already been replaced by the previous owner in an attempt to fix this problem. You can usually get the controls to kick in by using other functions at the same time as the one you're trying to use. One pump is definitely way worse then the other.