M59 bucket and hoe won't lift at an idle...

[Tags]

A friend of mine just purchased a used M59 with 650 hours, its in good shape, it was a rental machine I believe. It will not pick up the loader or the backhoe boom up at an idle, it doesn稚 even seem to load the engine at all when you try and it seems like the loader and hoe operate a bit slow when running at almost full throttle, but it will pick up a very full bucket of roadbase to full height and the hoe will dig and lift the machine no problem at higher rpms. Ive run these machines before and they will pick up the loader and the hoe at an idle. I'm wondering if it was a rental machine if the reliefs were turned down and if anyone knows how to check and where to check pressures on this machine? I did check and confirm that the two levers in back to switch from hoe to three point hitch were pushed all the way in and that the cables for the loader were moving the valves to full stroke. He ordered a WSM but hasn't gotten it yet. Also just wanted to add that the hydrostatic transmission seems fine and has no problem spinning the tires in 4wd.

 

[rScotty]

You check the pressures by putting a pressure gauge into the hydraulic system anywhere. There are separate systems for front and back. Easiest access is via an accessorty port. Use a 5000 psi gauge.
Relief valves are easy to adjust by I doubt that is the reason for the low pressure. If they were set too low, it wouldn't work at high RPM.

There are three simple possibilities for the low pressure at idle. One would be a worn hydraulic pump, another would be worn hydraulic cylinder seals, and the third would be a low suction flow from the hydraulic fluid reservoir due to a mostly plugged fluid filter. Of the three possibilities, the third is probably it but doesn't matter because even if it isn't the problem you still have to start there and troubleshoot by replacing the two spin-on hydraulic filters and all the hydrauic fluid. Doing this will cost you a few hundred dollars or more in hydraulic filters and get brand new Super UDT hydraulic fluid.

For right now lets assume that the problem is low flow due to oil and filters. Once we deal with that we can move on to pressures and relief valves. You want to use Kubota filters and oil - especially when this is being done partly for troubleshooting.

Just so you have something to think on and to answer some of your questions, the easiest place to test the hydraulic pressure is at one of the accessory hydraulic outlets. On an M59 there is almost always a front accessory outlet on the front loader arms that is actuated by a lever below the loader control. Look in the operator's manual. Don't operate that lever for very long without an implement on the remote or some way to allow fluid to flow. It isn't made to be deadheaded all the time. Relief valve Pressure on the front circuit is 2780 to 2910 psi. It isn't uncommon for actual system pressure to be ten percent less than the lower figure. You'll never notice that difference.

I'm not sure, but believe there is a separate relief valve on the main system for the rear accessory outlets - I know there is for the BH swing circuit because it has a separate pump and relief valve. It's pressure is 2420 to 2560 psi. But like the front system it might not make that pressure. If it doesn't have a rear accessory hydraulic outlet you can measure pressures by uncoupling the hoses that you normally uncouple for changine the backhoe to the 3pt hitch. Again, the operator's manual has a separate section on uncoupling and moving those hoses. so check the operator's manual. That manual and the Backhoe Supplement are necessary for working this tractor.

BTW, congrats to your buddy for ordering the WSM. Might as well get all the technical info that you can. There's an old thread here on TBN dating back to when the M59 first came out that runs to about 60 pages!
I've got copies of the old original M59 sales brochures which I can post if he is interested in that sort of thing.
luck, rScotty

 

[Hersheyfarm]

You can check pressure at any cylinder. The main relief is under the seat I believe ,there is a access plate. Its by the knob you adjust the 3 point hitch speed.

I had an m59 and lost the pumps and it started with no movement at idle.

As What Scotty said, if the problem is a suction problem I would think you would get some sort of sounds from the pumps. A wine or a hum.

 

[Tags]

Thank so much for the replies. He also bought new filters and fluid from the local Kubota dealer and was changing it this weekend. The machine is very clean and the loader and hoe are tight, doesn't look like it's had a hard life, but I imagine if someone had disconnected the hoe to use the three point hitch and didn't pull the levers out or didn't connect the hoses properly this could cause pump damage...I hope not for his sake

 

[rScotty]

You can check pressure at any cylinder. The main relief is under the seat I believe ,there is a access plate. Its by the knob you adjust the 3 point hitch speed.

I had an m59 and lost the pumps and it started with no movement at idle.

As What Scotty said, if the problem is a suction problem I would think you would get some sort of sounds from the pumps. A wine or a hum.

I agree you might get a sound with a suction problem. For that matter, a relief valve also makes a sound that is unmistakeable- unless it is jammed open and then it would fit the symptoms.

But you have to start somewhere and I like to start with the simple things first, and this has to be done anyway. Might as well get the simpler things out of the diagnostic path before we get into valves and then cylinders and then to pumps.
None of which is the end of the world.

He might have problems getting the filters off. Tell him to make sure that the nipple the filter screws onto is screwed tight into the block. It's just a pipe nipple and they do come loose.
rScotty

 

[Smokeydog]

I’ll second the good advice above.

 

[Hersheyfarm]

I agree you might get a sound with a suction problem. For that matter, a relief valve also makes a sound that is unmistakeable- unless it is jammed open and then it would fit the symptoms.

But you have to start somewhere and I like to start with the simple things first, and this has to be done anyway. Might as well get the simpler things out of the diagnostic path before we get into valves and then cylinders and then to pumps.
None of which is the end of the world.

He might have problems getting the filters off. Tell him to make sure that the nipple the filter screws onto is screwed tight into the block. It's just a pipe nipple and they do come loose.
rScotty

Why wouldn t you start with the easy/simple stuff first? I would.


OP, Scotty wants me to tell you to make sure the filter nipples are screwed tight into the block. They can become loose.

 

[rScotty]

Why wouldn t you start with the easy/simple stuff first? I would.

Hersheyfarm, I don't know the answer to that one. At my repair shop I finally concluded that it's just part of the mystery of human nature to want to jump ahead if there is any chance that the solution is going to be more complicated.

It will be fun to figure this one out. Lots of good info in the OPs original post. If the oil & filter don't do it, next step will be a simple pressure gauge plugged into any accessory port.

On our old JD, I've still got a $20 fluid-damped pressure gauge on a tee fitting mounted right to the input fitting on the FEL valve block. So I can't look at the loader controls without also seeing the pressure to the valve. Very educational to watch the pressure change as it works. The gauge has been there about 30 years so I guess it's become permanent by now.

BTW, fluid-filled gauges are typically filled with glycerine & like any glycol solution that's means they can freeze in winter. Take a look at the chart below.... it's a weird chart.....wildly non-linear. The gauge I bought uses pure glycerine for better needle-damping characteristics, so I opened up the threaded plug on top of the gauge, drained the glycerine out, measure it, diluted with distilled water to lower the freezing point, and refilled.

Sometimes even something that seems simple turns all crooked & complicated.
rScotty

 

[Hersheyfarm]

You know that nipple configuration on filters can let a lot of unfiltered fluid circulate if they are really loose, and that amount increases more as the filter gets dirty. I'm curious and will pay attention next filter change. By making it tight into the block you also pull the bigger tapered part from the filter itself. Probably not a huge amount but still a place for a bypass. I would say ideal would be to have the nipple finger tight into block. This is all assuming that the nipple is a double taper. Straight threads and it doesn't matter anyways. The only real way to to avoid this is a double o-ring seal on the filter, and I have never seen this.

Again this is probably a small amount but I have seen pretty loose threads in other applications.

 

[Smokeydog]

Always Good to check for tight nipples. Also hard line and rubber connections on the suction side. B26 has a problematic rubber elbow on the suction side of the pump that will allow air to in-leak. Doesn’t take much air to hamper a hydraulic system.

1996 dodge diesel fuel fuel filter has rubber ring gasket for the nipple thread connection.

Took a chance on a 2014 M59 TL with 1000hours and original hydraulic filters in place a few years ago. Didn’t operate much before changing fluid and filters but didn’t note a loss of performance before or increase after change. Now 300 hours later a strong, trouble free tractor.