need help HYD. To-30

[T. Tucker]

I recently bought a '53 TO30. The hydraulic oil had a lot of water in it so I drained it all out, flushed with diesel fuel, drained and replaced with napa gl1 90 wt mineral oil as recommended here. The lift now works fine for 5-10 minutes, then it gets "tired" and won't lift after this time. If I let it cool off for a while it works again for 5 minutes or so. I pulled the pump and everything seems to be in spec. I also looked at the cylinder while it was running and didn't see it leaking any....Any help figuring this thing out would be appreciated. I was gonna put a new relief valve in but I ain't sure whats wrong and can't throw money away on stuff I don't need...TIA for helping me...

 

[Jerry/MT]

did you check the cylinder for leakage when you had a load on it and the fluid was warmed up from some use?

 

[John (UK)]

The mistake you have made here is to remove the Pump before you asked what to do, as we cant tell you what to look for now, it could have been anything and it is much easier to find out before you disturb it. But do change the Safety Valve as it will most likely need changing anyway and certainly the Check Valve on the end of it will. The Pump losing power like that after a few minutes running is likely to be the valves in the Side Chamber sticking, they could be rusted if they have been sat in water, so they need to be checked. You don't need to take the Pump out again,(but it is easier) you can do it through the round port hole on each side, remove the circlip from each of the two valves in each side chamber and screw in a small bolt into the cap to lift it out, then you can lift the Valves out and see what state they are in. You may need to polish the stems with metal polish to get them to move, the springs maybe rusted or broken, if this is the case the best thing to do is fit fit new valves and springs and Safety Valve. If you would like this all written out in greater detail, just email me at [email protected]
tell me again what you need and I will send it, with anything else that is necessary.
You said you didn't have any leaks from the Lift Ram when you tested it, did you have a heavy implement on the back when you tried to lift to make it leak?..John