I have been advised to change/replace the hydraulic oil before moving on with other repairs. I bought 30 gal. of Mobilfluid 424 as JLG recommends and the two filters, pressure and return. I would like to know the step by step procedure so I don't cause any problems or damage such as air in the pump. The service manual doesn't get into it. It just tells capacities and recommended oil and filters. If anyone could give me the step by step procedure I would greatly appreciate it. It has the Deutz diesel it it.
I don't have step by step instructions but I recently broke my hydraulic hose below the reservoir. I drained all the fluid and replaced the hose. My lift would not do a thing except start and I had no idea why. I tried bleeding the lines (improperly). I ran into a guy who use to work with lots of hydraulic machines. He told me to bleed the line coming straight from the pump. As soon as I turned my wrench on the connection everything jumped and worked. So if you decide to wing it bleeding the lines isn't too bad. This was a jlg skytrak 6036.
Thank you for your input. I changed the oil back in Sept.2015 just by using common sense and seeing what Genie said about it. Jlg gave you nothing at all to refer to but Genie did for a comparable boom lift. They said to shut the valves on the input and output of the pump at the hydraulic tank before draining it, but I had none. They also said to shut the fuel valve to the engine, and crank the engine for 20 seconds, rest for 20 seconds and then do the same two more times after refilling the hydraulic tank. This primed the hydraulic pump at very low speed versus starting the engine and ruining the pump. Any way, it worked out well and the lift functions seem to work much better with new oil. The whole system would take 33 gallons but the tank only took 28 gallons when I refilled it so I really only changed about 85% but it was all I could do. I got the exact oil recommended by JLG which is Mobilfluid 424 and also replaced both hydraulic filters. Now I am quite satisfied with the way the lift is functioning. Again, thanks for the input !