Mitsubishi D1650 hydraulic 3pt failure mid operation

[JeffreyR]

Hello all. I really hope someone can point me in the right direction with a problem my tractor has. I've spent my free time the last couple of days searching for likely causes to the issue but for my particular case I'm coming up empty and am just wondering where to start.

I use a finishing topper weekly to mow the part of my field the family and dogs use for playing on, running etc. On Saturday I was out mowing. The tractor worked fine. I keep the finishing mower on the tractor parked up with the mower resting on a skid/pallet. So I lifed the mower off the skid/pallet, moved the tractor forward then dropped the mower back down to ground level and set off mowing. Once finished I returned to park the tractor back up and the 3 point would not lift. There was just absolutely no response to moving the lever. No sound, no movement... nothing. Previous to this it had always worked fine. Good resposiveness, no sounds, no hesitation - it just worked as it sould.

Prior to the season starting (3 months ago aprox.) I made a point of changing all the tractors fluids and cleaning/replacing all the filters. The old hydraulic/gearbox oil was fine and the filter was pretty clean but I still gave it a full clean and changed the fluid. The fluid is still at the correct level and from dipping it looks very clean. I've checked my hyrdaulic lines and they looks completely fine externally, there are no leaks and no visible damage to the lines.

So where should I start with this one? As someone new to any sort of hydraulic troubleshooting my first thought was the pump. This is a pretty pricey part though so I just want to ensure I'm covering all the bases here before I commit to it. Is there anything else I should be checking, opening up, having a poke at, etc before I consider the pump?

All help and advice would be very much appreciated

Edit to add: Its also not the control/restriction valve under the seat. This was the first thing I tried.

 

[Roadworthy]

I haven't a clue where to start but some part of your linkage may have slipped off. Try checking with Valley Power for suggestions. They're quite helpful.

 

[JeffreyR]

So I had some unexpected free time today and figured I'd do some investigating since it didn't look too difficult to get access to the linkage. The case was sealed good but after a few taps I could see what I was looking for. The lever is still firmly connected to the linkage and appears to still be opening and closing the valve. I have a parts manual but no actual repair manual so I can't say what the freeplay of the valve should be but the lever is opening and closing it. Seems I can rule that out. So I'm now at a clean case, clean oil, clean filter, no line damage, working linkage... surely at this point its gotta be the pump?

 

[Roadworthy]

I had a D2350 for a number of years. The older style pump was more prone to failure than the newer style but I don't know why. The cases look slightly different but they bolt in exactly the same. I did have to replace my original pump due to failure - no pressure, no output. I don't think they can be rebuilt, at least not by my local hydraulic shop. They are available on eBay but the price is nearly $300. Most are from China but I note one seller in Canada advertising the same price. Good luck!!

mitsubishi d1650 hydraulic pump: Search Result | eBay

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[JeffreyR]

Just to come back at this thread some months later. One thing I didn't do in my initial testing which could have gotten me to the problem a lot sooner was trace the hydraulic fluid by very slowly undoing some bolts in the lines just enough to seep a drop or two of oil. When I did finally think to do this (before ordering the pump, thankfully) I found that hydraulic fluid was flowing to the bypass valve but not beyond it. Remembering having read a post about debris causing a bypass valve to stick in another D1650 I decided to pull out the bypass valve, tear it down and clean it. At the same time I replaced the o-rings. After bleeding the system everything worked as it should.

 

[JeffreyR]

Thank you for this information, I will pass it on to my husband. He has been suffering for 5 days now.

If the problem is the same I would start by looking at the bypass valve which you can see in that video bolted to the top right of the case. Once the case is open its very easy to take it off and clean it so its worth doing. Mine didn't look particularly dirty but clearly there was enough to cause the system to stop working.