The steering got tight to where it took everything I had to turn the steering wheel while in motion. And it is still very tight when moving. In the past when it started to get tight I would top up the steering fluid and all would be good. Three days ago this didn't do any good. I first changed the filter. Still very difficult to turn the wheels while stationary or moving. If I lower the bucket to lift the front tires the steering wheel turned freely. Today I replaced the power steering pump. Still difficult to turn the wheel when stationary or moving. When I put the bucket down to lift the front tires I can turn the wheel but it is now not as easy as it was before the pump replacement. The steering cylinders have always leaked a bit since I bought it in 2007. Yes, the king pins are a bit sloppy and the bushings are sloppy where the cylinder rod attaches to the wheel assembly but I seriously doubt any of this is the issue. Any input will be welcomed. Thanks.
Did you bleed the air out of the pump and gear? Pick the front wheels off the ground and cycle the steering wheel from one lock to the other. Try 15 or 20 times and see if it's better. Might take more time if you have some spot that traps air. If you have air in there, the pump compresses the air and not the oil, so you don't get much boost.
Is the replacement pump a brand new 580 B pump? Is the relief pressure set properly? There's also a 'shuttle' valve where all the steering lines connect that might cause your problems if it failed. When I was having steering issues with my machine I was advised that these almost never fail, but I took it apart anyways (it was fine). Maybe take a look at it if you get desperate.
Thanks for the responses. El Hombre, I did bleed the air out of the system. I worked the wheels back and forth over 100 times but no improvement. I left the wheels lifted, shut the engine off and rotated the steering back and forth and the wheels turned in response. From what I have read this test indicates that the orbital valve in the steering column and the cylinders are OK. CasIns, The pump was brand new so I would hope the relief valve is adjusted properly. I think I will move onto the shuttle control valve as that is the only item I have not checked out. I used my infrared temp gun and took some measurements throughout the power steering circuit. The temps were very consistent, (within a few degrees) from the pump to the valve but the temp jumped over ten degrees at the port that returns fluid to the pump. I think the spool is stuck and fluid is simply being pumped to the valve and then immediately back to the pump. Going to disassemble the valve and will let you know what I find.
Update - No progress or success yet. I removed and inspected the spool from the steering control valve. Neither the bore or spool showed any abnormal wear or burs that would tend to hang up the valve. I made up a little test set up consisting of two hoses, a pressure gauge and shut-off valve. I connected this between the pump return line and steering control valve port. NO Pressure unless I turned the steering wheel with the shut-off valve opened. Then connected the test set up between the pump discharge and spool valve. NO pressure even with the shut-off valve closed. I disconnected one end of my test set-up from the steering control valve, fired up the back hoe and opened the shut-off valve. Had some flow but no real pressure. (couldn't measure the flow but it was low.) Tells me the pump is not putting out. The pump is new and the last thing I suspect is a new component. I removed the pump to inspect it. All looks well. I verified the drive gear in the front cover of the engine was rotating and verified the gear on the pump rotates. I can hear hydraulic fluid gurgling as the pump gears turn so the shaft key didn't shear. Any ideas aside from contacting the pump supplier????
We used to pack the gears of a car's new oil pump with Vaseline; that would prime it instead of cranking the new engine over and over with no oil pressure. I don't know how far your pump has to draw oil, but new pumps and priming can be a real PITA...
I reread your first post. The machine does steer, it's just difficult? Did you hit anything with the front wheels right before the problems started?
Thanks again for your input. I used vaseline in the oil pump when i used to rebuild engines. It worked great. The power steering pump on the 580B has a submerged intake and with a positive gear pump there should be no issue in establishing flow. Today I blew the pump intake and discharge lines out with compressed air and reinstalled the power steering pump. Same thing. Yes I can turn the wheels if they are off the ground. I wish I had hit something as it would make some sense to what is going on. With the bucket raised and the wheels firmly on the ground I am not able to turn the wheels unless I maintain constant torque on the steering wheel and it will turn ever so slow. I do have a lower spindle bearing that is in pretty bad shape. It may be possible that when full weight is on the wheels it is binding up. But that would not explain why I did not read the proper pump discharge pressure. Is it possible there is some air binding occurring? Because the pump is a positive displacement pump with a submerged suction the manuals state that all air should be evacuated simply by turning the wheels back and forth. The manual doesn't say anything about - what if the steering still does not work. Has anyone ever heard of having to crack open hydraulic lines in order to evacuate air fromt he system? Thanks in advance.
Keeps coming back to a faulty pump; even if it's new, that's no guarantee it's good. When I wrenched for a living, the service manual said to install a 'KNOW GOOD PART'. They can be bad right out of the box. You're not getting any pressure or volume out of the the pump, bad pump.
Well all I can say is I've had the same steering symptoms on 2 occasions with my machine. The first time it was because of the relief pressure of the pump, and the second was because I broke the piston off of one of the steering rams. As I recall it's pretty easy to adjust the pump relief pressure, I think you just need to take off the reservoir and the filter/spring. There's a big set screw compressing another spring, just try turning in the screw a few turns and see what happens. You could also have a steering ram that's bypassing past the piston or the piston is broken off. If the cylinders are already leaking you might as well repack them. Was there any indication that the old pump was bad, other than no steering?