Hyundai 160-9alc

[adambowers123]

We have a Hyundai 160 -9a that is in our fleet. We are primarily a trucking company and my mechanics are diesel engine technicians. This unit has been giving us fits for the past 6 months. When at operating temp, the joysticks will start to jerk and shake uncontrollably to the point of having to turn off the hydraulics and let it settle, and restarting. This does not happen when cold. It primarily happens in swing function, but can happen in any motion. My guys have looked and tracked, to no avail. We called our local Hyundai dealer, he put gauges on the pump, said it was weak, and needed replacement. We ordered a aftermarket pump, drained and flushed system, replaced and no difference. We called back and that dealer has given up the dealership. Next, we called the new dealer, had a tech come out, and he said it is the swing motor. I hate to keep pulling at straws, and throwing parts at this unit, but it is out of our typical scope and even the local dealerships are having trouble diagnosing.

 

[uffex]

Good day & welcome
The pump you replaced I guess is the servo pump! have the servo pressure been checked ? Did this issue appear all of a sudden or is there any history?
Kind regards
Uffex

 

[adambowers123]

We replaced the entire hydraulic pump including the servo pump. We have not yet tested the pressures but will do so once I can locate what they are supposed to be.

 

[uffex]

Good day Adam
Servo pressure is reacting on the RCV remote control valves or cabin levers 570 psi. this needs to be constant across the rev range. See attached.
Kind regards
Uffex

 

[uffex]

Good day
In the pump house, follow the output line from the servo pump. It should go to a block with an accumulator. Attached to the block, you may see a test point. This is where to check the servo pressure. Needless to say may the check with fluid at working temperature.I have checked, I do not have a good illustration of the test point.
Kind regards
Uffex

 

[uffex]

Good day
Found a illustration, port "P" or "T" into the delivery line. See attached.
Kind regards
Uffex

 

[uffex]

Opps must be slipping on the pump you have a test point.

 

[uffex]

Good day
Additional information please see attached.
Kind regards
Uffex

 

[adambowers123]

it appears we have 575 psi at the pilot pump. We tested the accumulator by warming machine, raising boom and shutting off machine. We attempted to lower the boom and no functions would allow lowering the boom.

 

[uffex]

Good day
We may have an issue with the pressure becoming blocked, please see attached and change the filters.
Kind regards
Uffex

 

[uffex]

Good day
Explanation of our suggestion, please see attached. There may be an additional screen filter in the pump feed line connector, see 25. I will try to find a good illustration.
Kind regards
Uffex

 

[uffex]

Good day
The screen filter will appear as a normal fitting, be sure the servo pressure holds up with low revolutions. See attached.
Kind regards
Uffex

 

[Lagwagon]

If the screen filter isnt where arrow indicates it’ll be below the outlet line on the servo pump. remove 90 degree fitting and screw out adapter and it could be under there. Basically inside the barrel of the outlet just about at the same level as that test port.

 

[uffex]

Good day
When servo pumps fail, the outlet can be subject to a high level of aluminum debris. As the unit has been replaced it may well cause issues down stream. If you work your way along the line, be sure to check the control lock out solenoid, some blockage may cause vibration if it is prevented from opening and closing. Your post stating that the accumulator has no effect I assume the test carried out was with the control lock out in the working position. The control lock out solenoid has a manual overide according to my schematic, this is good for troubleshooting. When you tested the serrvo pressure was the vibration active?
Kind regards
Uffex

 

[adambowers123]

Greetings all. To update everyone after changing the accumulator and all filters the machine seemed to work correctly for approx 10 hours of run time. After that we had another issue pop up that is similar. Now on certain functions- boom up and bucket curl, the machine vibrates and feels like there is hydraulic fluid fighting in a circuit. We still have 575psi constant at the pump.

 

[uffex]

Good day
Boom and bucket use a common pump do you get the vibration on one track also?
Kind regards
Uffex

 

[adambowers123]

Yes we do.

 

[uffex]

Good day Adam
That points to the pump, either drawing air or some damage to the lens plate. I guess you have checked the suction filter, for a short test remove the filter. Be sure you have the correct fluid in the machine.
Kind regards
Uffex

 

[adambowers123]

I have attached two videos of wha the unit is doing. It’s chattering through most functions. The small line in the 2nd video seems to be loading up as well.

https://www.dropbox.com/scl/fi/qc6k...3-PM.mov?rlkey=dvtzpmwnrod0v3p383iwunnfk&dl=0
https://www.dropbox.com/scl/fi/xar0...7-PM.mov?rlkey=plrt73q04143l4x6gyh3tcdxe&dl=0

 

[uffex]

Good day Adam
Have you a pump shop nearby that could test your unit?
Kind regards
Uffex