Contaminated Hydraulic Oil - 5600D

melgibson · Aug 30, 2018

When the machine hydraulic oil is at operating temperature (ie Hot, not cold), I get a squeal at different
parts of the machine when UNDER LOAD (like going up an aggressive hill I get a squeal in the rear, or just holding the bucket control past the
stop squeals at the lift boom, etc.).

A literature review reveals this could be water or air contamination, both bad. I think it is air.

A couple of potential causes- a leak in the system, or, when I "changed" the hydraulic oil recently I got air in the system when running the machine and the oil reservoir was not full (level below the feed tube.)

Bottom line is that I think the hydraulaic oil needs to be thoroughly removed and replaced. However, there is no drain plug- the resovoir holds a portion of the system oil and the rest is in the lines and devices.

Question- I don't know hydraulics, so how do you get all the oil out of the hoses and devices (pump, valves, etc.)?

Thanks

Jabonee · Aug 30, 2018

No way to drain hydraulic fluid completely. Have you checked the pump drive belt tensioner?? :confused3:

DEWFPO · Aug 30, 2018

Just Thinking.......I've never done this before but it would seem to me you could put the pump feed line into a 5 gallon pail of fresh hydro fluid and put the return line to the reservoir into an empty pail. You'd still have to drain the reservoir. Make sure you use all the hydraulics, dump bed, 4 wheel steering, boom, cooling fan, aux. hud. and drive wheels to get the new fluid throughout the entire system.

DEWFPO

100 td · Aug 31, 2018

melgibson said:
there is no drain plug- the resovoir holds a portion of the system oil and the rest is in the lines and devices.
Question- I don't know hydraulics, so how do you get all the oil out of the hoses and devices (pump, valves, etc.)?
Thanks

Pull the hose of the bottom of the tank to drain it, but as with any hydraulic system there is oil in cylinders/hoses etc. Depending on the machine and your requirements, you drain what you can, use the machine and drain again a couple of times, over time. Like an auto transmission on a car may take 3 litres for a drain and refill, but holds 12 litres in the torque converter/box/hoses/cooler/piping. It's done as a multiple drain and fill over time, or as a flush, but as previously mentioned, you would need to be operating at the same time to get everything out unless you individually drain everything. Air in the system should self bleed, unless it is being continually introduced at a fitting or hose on the suction side of the pump. When you changed the oil recently, did you fit the new hydraulic filter correctly, and ensure the old gasket was removed? Did you use an OEM filter or aftermarket?