I finally got around to putting a remain used pump on 555E. I set main relief valve psi 2700 psi the went to check rear pump relief psi at 1500rpm should be 2500. When dead headed it goes to 2500 psi but then drops to about 1500. Outriggers only lift the back so far then it just stops.What could cause this. I have adjusted the relief valve in and does not effect it. Any ideas? Thanks
If you are using test port 3, lower, running at 1500 rpm and holding the stab lever in the retract position it should read around 2550 psi.. The relief valve is in the stab valve next to the frame high up near the floor. My question is your pump hookup lines at the rear pump. You have for lines on the flow selector, find the steering valve under the hood, should have five ports, four should be two/two. The lower left line should go to the tee fitting on the rear of pump. The single line at the steering valve should go to the fitting going in the side port which makes up the standby pressure to shift the internal spool sending flow to the stab valve. The other line at the tee should go to the center pressure port at the hyd test port. I would recheck these lines with the parts book since you have had to removed them, it can cause some issues you are having. I think I have told you correct on the line install but check your parts book to be sure.
I will definitely check the routing of the hydraulic lines. But what you're describing sounds correct on the way it is hooked up right now. When I check it at 1500 rpm using the lower test port it does read really close to 2550 psi but will drop pressure down to around a 1000 psi. Then I release the lever and activated again it will go back to about 2500 psi and then drop back down to 1000 psi. Tomorrow I will check the hydraulic lines and make sure they are routed right.
I checked the hoses making sure they where routed correctly. Everything looks good. Is there anything else that could cause the pressure to leak off
pressure issues The loader and stab valve should have the same type main relief valves. I would go to test port 1 and back the loader relief off to 2500 psi. Turn the machine off and work all control levers to get the pressure off the system. Unscrew the relief out of the stab valve, make sure you get the large/whole relief at once. Clean it up. Remove the one in the loader valve and have the stab one ready to stick in. Lots of oil if your not ready. Reinstall the loader relief in the stab valve. Start and check pressure on the loader valve and try to adjust it to the 2725 psi. Check the stab to see if the problem is still there or did the relief swap cure the problem. This is the step I would do next, if the stab works I would pick up the couple O-rings from NH and replace them in both reliefs. You should be able to do this in about 10-20 min., that stab relief valve is not in the best spot for easy removal. Did you have the 100 psi standby pressure and full pressure while turning the steering stop to stop on # 2 test port?.
Ok I did as you suggested. Nothing changed. I am at a loss as to why it will not hold the 2500 psi. I did try the stabilizers while it was cold and they lifted the backhoe to full extension. I thought ok must be working now. But the warmer the fluid got it went back to not lifting like it should. The steering stand by psi is good and I get the 2000 psi at full stop.
pressure issues Do you still have your old pump?. In your other post you said you had the service manual. I am still not sure that you traced the lines in question by hand for the correct attaching. My thoughts are the spool in the end section of your pump is shifting to the steering port. This can happen if the screen is plugged, trash the size of a ball in a ball point pen is blocking the orifice that shifts the spool to shut the flow to the steering, or it's getting sensing line pressure from the steering valve when the steering wheel is in neutral closing the port that sends oil to the stab valve. If it were me, I would unhook the line to the sensing fitting on the side of the pump. Run it into a 5 gal bucket. Slide a hose on the fitting on the pump (5/8 heater hose) ? and use a gate clamp to secure it, run it into the 5 gal bucket. Start you engine and see how much flow is coming out those two lines with a helper. Try you outrigger (stab) cylinders and see if they work with the sensing line not hooked up. We are trying to see if the oil from rear pump port is going threw the filter screen out the orifice hole, filling the area behind the spool and shifting back against the spring allowing flow to the stab main valve without the sensing line pushing against it closing the stab valve port and sending it to steering shutting the flow and causing the stab not to work. If you still have your old pump, remove the fitting that the sensing line goes to, it will have some spring pressure, remove the allen head plug on the other side, push the spring and plunger out the hose side. In the fitting you will see the small orifice, on the spool you will see the allen headed set screw which has the orifice and the wire screen along with the other orifice in the end. The smallest trash/sliver of metal/part of an o-ring can cause issues. You steering valve has several checks that could be not sealing, centering springs worn leaving just enough to allow a sensing flow. Does your machine have a hand tool connects in the center with a dash switch or a pedal next to the backhoe control tower.
Yes I did trace out the lines by hand. Just to make sure. I do have the old pump. This weekend I will do your suggestion. I'm not sure what you mean on the last part of your reply. About hand tool connects?