New here. Looking for some help. I have a 1979 580c backhoe the loader bucket roll back and dump are very weak and bleed off when lifting anything heavy. The lift works just fine just a very weak bucket. cylinder's seam to have good packings but when I test them with the line disconnected I get lots of fluid out of the disconnected line not the cylinder. Any ideas?
Possibly there is air in the cylinders. After you reconnect the hydraulic lines, bleed the air from the system. Possibly low hydraulic fluid. Possibly a piston seal is worn. Possibly the relief valve setting is too low or leaking. Possibly the secondary relief valve is too low or leaking. A flowmeter is needed. Possibly the spool is worn.
I did test b got no leakage from the cylinder but the disconnected line shot out fluid. had to plug it to test cylinder. Also I replace the o rings and back up rings on the secondary relief valves. Spool seemed to be in good condition no visible wear and fit nice and tight. You said flow meter? not sure what test that is. Thanks for the response and help.
Try to use the bucket tilt a little bit, and then go out and put your hand on the cylinders. If one of them is hotter than the other, that indicates the packing is leaking by inside. The fluid blowing around the piston causes the cylinder to heat up. You may need to work it a little bit before seeing if it's getting hot.
The service manual details four tests using a flowmeter, these tests will determine if the problem is because of packing, main, or secondary relief valve. I have not performed these tests. Hopefully someone that has can add to this thread!
Thanks for the help. I have low pressure in the secondary relief valve. added a shim and seems much better. I will test the pressure again and get it set correctly. Also found a bad linkage that was not moving the spool far enough. That fixed the slow tilt problem.
Remove one line from one of the cylinders. Start the tractor and dead end the rod and hold the control lever in position. If oil comes out of the cylinder port you have a leaking piston seal. Do one cylinder at a time.