Hydraulic growl

[apatche1964]

I have a terex hr16 mini excavator with 2300 hrs and it works smoothly for about an hour then it begins to growl in the hydraulics whichever lever you push. It still works ok but i'm afraid something is going to give out. I've cleaned the filter and most of the fluid due to a cylinder breaking but i'm at aloss to determine the source of the growling it seems to come from down underneath the machine

 

[GE222]

Sounds like the hydraulic pumps are being starved for fluid. Besides a filter, check the suction line from the hydraulic tank. There probably is an inlet screen which could be restricting flow. I'm sure you have checked the fluid level.

 

[kjung17]

Agree with GE. Check that suction screen.

 

[jinman]

I hate to disagree with the previous two posters, but a dirty filter screen would cause problems all the time, especially when the machine is cold. It's always good to check filters, but your problem sounds like a pump is getting hot and a bearing is "growling." Before you move a lever, the system is running with minimum pressure due to being open center. When you move a lever, the hydraulic system goes to full pressure and it would seem the pump is making noise or maybe there is a pressure relief valve stuck open and that is what you are hearing. I kind of doubt the pressure relief valve because it also would make noise when the system/oil is cold. Can you feel of your hydraulic pump or measure its temperature to see if it is getting hot? Not being a Terex expert, I can't say exactly how your system is plumbed, but the pump or pump drive gearing seems to be the culprit from your description.

 

[kjung17]

Oops. Misread OP. An hour of smooth operation would not be likely with a BLOCKED suction screen. It sounds like you may be getting air in the system. A slight restriction on the suction side could, still, cause cavitation during high volume use. Short of a low oil level, the suction screen still seems like the first thing to check. Does your oil look foamy when you hear the noise?