Hi, I am new here and also new to the used machine I purchased with 1400 hours on it. I am worried it has pump issues? I replaced all the fluids and filters, engine, trans, and hydraulic system. I noticed the hydraulic oil has small bubbles in the tank when drained, when running the loader the pump is quiet but when I switch over to the backhoe it whines. I have run and drained 40 gallons of new fluid in the system in attempt to clean up some of what was in there, I think it had some water in the system by seeing some water droplets in the tanks sight glass, is smells burned a little also. I am sickened by the expensive mistake I might have made. It does operate fine but I know the cavitation I am hearing is not right. Any advice would be great, Thanks.
Was the system working fine before you did the oil and filter replacement? A pump flow test would be in order and would tell you the condition of your pump. Even a suction hose leak would show up on a flowmeter. Did you use Case brand filters or a aftermarket brand? Did you use hydraulic oil within the machine specs? Im pretty sure the flow system in your backhoe is a full circular system, the flow runs through your loader valve and from there to your backhoe valve and then back to the tank. What I dont know is if you have a single stage pump or a dual because the plumbing could be different. Since the pump is driving the same oil from a common tank, I would think your loader flow would react the same way if it were a pump suction/ cavitation issue. There is a possibility that a problem could be in the backhoe control valve since the pump whine is only when you are using that end of the machine.
Tighten all suction line clamps from hyd. tank to pump. Look for wet spots on rubber hose and steel lines.
Thanks for your insight here, I operated it with original hydraulic oils in it with the original filters after purchase and it made the same noise, I purchased the factory repair manuals and have been studying them. I used aftermarket Baldwin filters in it and used premium fluid that cross references the factory fluid (Traveller Premium). I am thinking I should operate the loader only and look for bubbles instead of the hoe maybe it is in the valve for the backhoe, the pump only whines when the hoe is operated. I know it is a Bosch Rexroth series 31 axial pump, I need to check for suction leaks. Does water in the oil cause bubbles and cavitation?
I will check the hoses now
Thanks a bunch!, I found the 2" hose at the hydraulic tank was damp so I tightened the hose clamps and now no more air in the fluid. Kirk
Good deal