Loader Front Bucket Hydraulics

[gasmodesto]

Good evening all. I have a ym186d. Bought it in 2016 maybe start of 2017. Long story short I was diagnosed with cancer in 2018. Good news for me was that after chemo/radiation/ and a 9.5 hour surgery in 2019 they think they got it all. Now back to the interesting part. Started the tractor today (been almost two years since it has run). Have jumper cables will travel is my motto. Anyway jumped the battery 8 seconds of preheat and lo and behold I had a running tractor. let it run for a few minutes and when it started it lifted up the post hole digger that is mounted on the back. Hydraulics worked to lift it up. The lever was moved to full pick up and I moved it back to the neutral area. I know I didn't have it that way when i got off the last time so I am thinking that probably some neighbor kids were on it. The tractor is located at some property we own that is about 65 miles away. Only been up there a couple of times in the last couple of years. Anyway I pulled on the loader controls and got nothing. No tilt (neither curl or down) and no raise or lower of the bucket. I am not sure where my manuals got put for the tractor. After this post my plan is start going through where my better half might have put them. Seems to me that there is an adjustment screw that controls the hydraulics but I really am not sure. I think I might have put 5 hours (probably a generous guesstimate on my part) since I purchased it, so I really am starting over like it was new to me.

 

[Roadworthy]

If you lifted the post hole digger to maximum height that could be why the loader no longer works. If your digger works off the three point try moving the control just a bit off maximum lift. Your loader may then be functional. (It's a thought. I've had that issue from time to time.) You might also check hydraulic fluid level.

 

[winston1]

Glad you are doing well. Pictures of your hydraulic plumbing possible?

 

[CoyPatton]

How do your supply and return lines connect to your loader valve? If quick connects, could whoever have pulled the loose to the point of no fluid flow?

 

[blackd]

If neither lift and curl are inoperable check to see if the lines are crossed. Never know what has happened in a years long sit.

 

[rScotty]

Good to hear you are doing OK.
The YM186D is one of my favorites. It was the one I lusted after when I first saw the new ones. Way back when.
Such a smooth little engine & powershift.

Anyway, I assume you've done simple things like check that it still has oil and maybe that the return line from the loader valve back to the transmission is flowing fluid.

And especially after a few years it makes sense to change the spin-on hydraulic filter if it has one....and to clean the cleanable transmission mounted one which always needs cleaning and is often the reason why hydraulics don't work.

And if those things don't do it then it is time to figure out which one of several hydraulic system you have. The basic YM186D tractor just had a simple junction box - called a pump adapter block which was a junction for the hydraulic pressure lines because all they did was run the 3pt and maybe the powershift. I'm not sure if the powershift tapped off the main hydraulics or had it's own tiny pump. Anyway, that pump adapter block was just a placeholder for some hydraulic connections that might get used laster. That box didn't have any parts, it was just a junction block and usually was on the right side of the tractor below the seat or forward by the engine on the right side.

Now if the tractor came with the Yanmar power steering or that was added later, then the pump adapter box was replaced with a similar box that did have some parts in it. This new box is a proportioning valve block that replaced the pump adapter block and insured that the power steering got fluid even when the rest of the hydraulics were also being worked.

Likewise, if the Yanmar loader was fitted that first proportioning valve might have been supplemented with yet another proportioning valve under the seat whose purpose was to run oil to the the loader valve.

Yet I've heard of YM186Ds that didn't have any of these proportioning blocks installed and just put up with only being able to use one system at a time.

Since with the proportioning blocks we now had PS, 3pt, powershift?, and now a fluid-hungry loader all sharing time on a undersized hydraulic system things got slow and complex. So the popular option was to put on a supplemental hydraulic pump for the loader alone. They was usually done off the front nose of the crankshaft and if done so you can see it sitting out front between the front grill and front bumper. If that was done, there was no need for the optional extra proportioning valve under the seat. Sometimes the supplemental pump used hydraulic fluid from the transmission sump and sometimes it had a separate supply - usually carried inside the right hand loader upright.

So if we do have to troubleshoot, we need to know what it has. But do the filters and fluids first. No since in inventing problems.
rScotty

 

[gasmodesto]

If you lifted the post hole digger to maximum height that could be why the loader no longer works. If your digger works off the three point try moving the control just a bit off maximum lift. Your loader may then be functional. (It's a thought. I've had that issue from time to time.) You might also check hydraulic fluid level.

i found the issue. There is a valve under the seat that adjusts for hydraulic feed. Evidently someone turned off the hydraulic pressure to the loader. Its working fine now. It could have been me, like I said I haven't started it up in 18 months

 

[California]

gasmodesto, good to read you got it working easily. And good to read you are back to good health.

rScotty, YM186D powershift has it own internal pump spun by the transmission input shaft. Aside from sharing the same fluid sump, there's no relation to the tractor hydraulics.

This is made obvious by the tractor lurching slightly no matter how skillfully you release the clutch. Engage the clutch pedal, spin that input shaft, the powershift pump comes to life and hydraulically engages a clutch pack in there, and off you go. Slipping the clutch can help slightly but its not a complete solution.

I think that design is also why Yanmar cautions you can't tow-start these. The engine and automotive-type clutch are the only way to spin that little pump inside the powershift. Flat-towing not only doesn't circulate fluid in the transmission, but also I think there are clutch packs that remain engaged as a light parking brake that have to be released by spinning the powershift pump.

 

[rScotty]

Right. Now that you mention it, I remember that powershift pump. It does share the same sump, I'll have to look in a service book to see just how it's fluid circuit goes.