- Hydraulic Oil Viscosity is Incorrect.
- Hydraulic Oil Level is Low.
- The hydraulic Oil Tank has Blockage of Main Suction Tube.
- The hydraulic suction manifold is blocked.
- Hydraulic hoses and hydraulic lines
- Steering lines and steering hoses
Note: Ensure that there are no active diagnostic codes for the hydraulic system.
Make sure that the correct viscosity of oil is in the system. Refer to Operation and Maintenance Manual, SEBU8408, "Lubricant Viscosities".
The hydraulic oil tank has a sight gauge on the outside of the tank. Check the hydraulic oil level with the machine sitting on level ground and the engine OFF. If oil is NOT seen in the sight glass, the hydraulic oil level is low. Refer to Operation and Maintenance Manual, "Hydraulic System Oil Level - Check".
Note: Make sure that the strainer is present in the filler tube before adding the recommended hydraulic oil.
If the hydraulic oil level is low, check for oil leakage.
Inspect the main suction tube for blockages or damage that could restrict the volume of oil drawn from the tank. (The suction tube draws oil from the bottom of the tank.) Removing the filler cap and the strainer will allow you to view the inside of the tank. It may be necessary to remove the tank in order to inspect the tank for damage. Refer to Disassembly and Assembly, KENR8559, "Hydraulic Tank - Disassemble and Hydraulic Tank - Assemble".
Blockage of oil flow can cause excessive noise at one, or all pumps, depending on where the blockage is located.
Remove the large suction hose from the rear of the main suction manifold. Inspect the hose and the inside of the manifold for any foreign objects that might block the flow of oil to the pumps.
Note: Ensure that you do not introduce any contamination into the system.
Kinks or restrictions in hydraulic lines and hoses may act like an orifice that creates excessive noise and heat as high pressure oil is forced through a passage that is smaller than the original opening.
Check for these conditions on all hydraulic oil hoses, lines, and tubes in the system or circuit in question. Correct any problems that are found then retest the hydraulic system for any symptoms.