I recently purchased an old 310 backhoe to use on my small farm. I changed all the fluids and filters throughout the machine. The old hydraulic/transmission oil smelled like 90 wt gear oil, so I used another tractor with a front loader to 'exercise' each cylinder and then disconnected each hose at it's respective cylinder and blew air (approx. 50 psi) back through the system to drain as much oil from the system as possible. Now, with the correct oil, the hydraulics don't seem to have much power. Everything moves fast and smooth through it's range of motion. The loader won't lift the front off the ground and the hoe won't dig. The out riggers will lift the back off the ground. Any ideas?
You've definitely got air in the system. It'll cause the oil to foam and the pump can't pump air. Loosen a line at your stabilizers and work the lever a little to let some air out until oil spews out. It's gonna be pressurized so stay out of the way. That should fix it. You may have to do the same thing on the lift and bucket cylinders but I doubt it.
I bought some Mobil hydraulic oil recently. It has the odor of gear oil. I am hesitant to use it to top off the machine since the look and feel of the lube that is presently in the trans appears different. Not sure the odor is the only clue to determining the correct oil. As to the problem: are you saying the loader doesn't have enough down force to raise the front wheels off the ground?
d9gdon,Thanks for the reply. That makes sense that there would be alot of air in the cylinders and lines since they were drained completely. I just assumed that moving everything back and forth several times would have forced all the air out. I did not actually bleed any of the lines. It's going to be a couple days before I can get back to it. I'll give it a try and let you know.
Did the machine have good hydraulic power before you changed the oil ?? Is the oil thats in it now foamy ??
oceanobob, Yes, the only thing that seems to have any power/force are the out riggers. Everything moves like you would expect, but when it comes up against a load it stops moving. I'm not sure about using smell as the only means of identifying gear oil either. I became suspicious, because the tractor came with a can of 90wt oil, so I called the previous owner and he admitted putting some in there to replace what he lost after a hydraulic hose broke.
koklsteele, Yes it did have good power. The oil is a little foamy now that you mention it and it's adding to the idea that d9gdon gave to bleed the air out of the system. I hope that does it. I was afraid it might be something like a worn out pump and the difference in viscosity between 'old wrong oil' and 'new correct oil' was the problem.
Thanks for your help, air was definitely the problem. I have most of it out and it's begining to work like it should again. There is still a little trapped in there somewhere however as the hoe bucket doesn't curl with full strength. So I'm going to try bleeding it out at that cylinder.