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Thread: Newbie Service Questions

  1. #1
    Senior Member CraneInnovation's Avatar
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    Newbie Service Questions

    Hello all,

    This is my first time posting in the shop forum, although I have learned an awful lot from you guys already.

    I am a new owner of an old Gradall (1990 G3WD) and it is my first piece of heavy equipment. I've been reading like crazy trying to plan my maintenance and overhaul plan. Its felt like drinking from a fire hose... Anyway, I had a few hydraulics questions as this area is largely new to me beyond the very basics (just learned what a pilot circuit is).

    The machine has been sitting for a while and its previous maintenance appears spotty. Should I flush the hydraulic system? If so, what is involved with doing it? I have access to a heavy truck shop, but they do not do much with hydraulics. Is it similar to the process/equipment used for flushing other engine systems?

    Gradall's service manual mentions getting the oil analyzed. I've seen that mentioned in this forum a few times. Where does a newbie look for someone to offer that service (particularly in the northeast)? What sorts of things do they provide data on?

    Our company uses bio-degradable oil in many of our machines, particularly pile hammers. Seems to remove quite a bit of the "oh shoot" factor from leaks. Would it be possible (or smart) to run a bio-degradable oil in an excavator if I'm changing the oil anyway?

    I want to tackle re-sealing and re-packing the cylinders. Gradall's service manual gives a great set of step-by-step instructions with pictures. Is this a task that someone with average mechanical skills could tackle?

    Thanks in advance for any wisdom...I know there's an awful lot here.

  2. #2
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    Before you go flushing the hydraulics, I would get an oil sample submitted. You can get oil samples done at your local cat dealer (I am sure there are other places, some of the more experienced guys here could probably tell you but that is the only place I personally know of). With it having been sitting it wouldn't be a bad idea to go ahead and pull samples from all compartments.

    Biodegradable oil I don't have any experience with but I'm willing to bet someone here does.

    Repacking cylinders can vary from simple to arduous. Smaller cylinders with bolt on or spanner heads can be done in house where larger "nut" style heads on cylinders require a cylinder bench or huge vise and pipe wrench and a crane.

  3. #3
    Super Moderator willie59's Avatar
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    Your first oil sample, unless it's raises red flags from contaminants, won't tell you much, it will be your "base point" from what you judge future samples. If hyd oil in tank looks clean and clear, I wouldn't bother drain/flush. If it looks dirty or milky white, different story.

    Also, what engine does that machine have?
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  4. #4
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    What kind of shape is it in? hours? How many of the cylinders are leaking? and are the wipers functioning? How much work do you really want to do on the machine before you use it?

    Testing, flushing, and biodegradable oil depends a little on the quantity you're talking about. Cat SOS tests are ten bucks, that's a no brainer. Before you use a machine that's been sitting, make sure there's no water accumulated in the bottom of the tank(s). If there is water, the last thing you want to do is distribute around the whole hydraulic system (or fuel system).

  5. #5
    Senior Member CraneInnovation's Avatar
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    Thanks for the replies!

    The cylinder heads are bolt-on and seemed to be designed for easy maintenance. Due to the PTO being inoperable, I have not tested the hydraulics under pressure. One of our company hydraulics guys did take a look and said he saw no obvious evidence of leaks. The telescope cylinder lines are new (rubber sections).

    It should be arriving tomorrow and I'll take a look at the tank. I assume that hydraulic oil is the same as other oils in that water will accumulate in the bottom of the tank? Yeah, I definitely don't want to flush things around the system, it has been sitting for a year, I'm told.

    Engine is the 6BT5.9 Cummins. It was replaced sometime recently by the previous owner and runs awesome. No smoke, even on first start. I've got a Cummins guy at the shop it'll be living at who can take a more detailed look.

    Transmission seemed to shift intermittently, but as another thread on this site mentioned before, its almost certainly electrical. It looks like someone got their ham-hocks into the electronics and left panels open to the weather. Replacing wire ends shouldn't be too hard, myself and a buddy have done plenty of that.

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