YM226D Project

[tc197]

Late on an update. Got the fluid changed, cleaned the strainer which was totally gunked up, hooked up all the hydraulic lines, and finally was able to test it out today. The only problem is the hydraulics aren’t working. Power steering isn’t doing anything and the loader isn’t doing anything. 3 pt has worked all along and continues to work fine. Im pretty sure I have everything plumbed in correctly as I copied it from the previous tractor and I know the hydraulics worked on it.

My initial thought was air because the loader was pretty empty from sitting and leaking, but everything ive found online says they self bleed after cycling the controls a few times.

It’s not weak or slow, it’s non existent. Any pointers on what to look at would be much appreciated!

 

[winston1]

Any chance of pictures of you plumbing?

 

[tc197]

Sure thing, I’ll get a video up shortly.

In my searches tonight I realized that deadheadding the pump is a thing. Apparently it’s a no-no to run the tractor with the loader not connected unless the quick connects are plugged into themselves? It makes sense in theory, but doesn’t based on the way my hydraulics are set up. I’d need separate hoses to connect between quick connects which just seems foolish. Might as well not even have quick connects. Anyways- since I definitely ran the tractor with the loader disconnected it seems damage to the shear key/pump may be likely. Would it make sense that the 3 pt hydraulics still work if this is the case though?

 

[rScotty]

Disconnecting doesn't deadhead the hydraulics unless it has been modified by someone. The return flow simply goes down the return line from the loader valve to the sump. No different than if you had the loader hooked up and weren't moving the levers.

Air is never a problem in an open hydraulic system. They will work with air in them and they self-purge. That's a lot of the reason why the transmission/hydraulic sump has a vent.

Did you take the cleanable hydraulic filter out of the side of the transmission and clean? What did it look like?
Made sure that the screw on hydraulic filter is a standard suction type & not some super low flow type.
rScotty

 

[tc197]

Here's a video of the plumbing on the tractor. Apologies if my terminology is incorrect.

Thanks for clearing that up rScotty. Yes I removed the cleanable hydraulic filter and cleaned it. First I removed the upper drain plug and drained the fluid. Then I removed the cleanable filter through the triangle shaped side port and it was covered in gunk. At this point I realized there was a second drain plug right beneath the cleanable filter so I removed that and drained the rest of the fluid. I then reinstalled both drain plugs and the cleaned filter. Yes, I also made sure to use the correct hydraulic filter (purchased from Hoye).

 

[rScotty]

Nice video. Well explained, too. The tractor is a nice one. Nice size and even has the special turf tires. Yes, I think you have one worth the effort - even if it is more effort yet.

I also think you have all the lines correctly identified. The problem probably is - just as you suspected - in that last line that is going from the loader valve (directional control valve assembly to be formal) down to next to the three point hitch drop speed control knob.

I believe that line is actually hooked to the "power beyond" port on the loader valve assembly. BTW, you can check that. It should be marked on the casting as "PB". That would be the proper way to hook up the hydraulics if the only hydraulics are the loader and 3pt.

But you also have a proportional diverter valve and power steering. As it is, it looks to me like you are feeding pressure to the hydraulics from two sources. One source of high pressure is fed directly from the pump to the proportional valve, and the other source of high pressure is coming from the the PB port on the loader valve.

I have no idea what is happening inside. Probably - hopefully - not much except for fluid confusion.

I'd say first step is to take off that hose from the PB port to the 3pt. knob. But there is a problem with just doing that & I'm not sure how to proceed. Let's talk on it for a bit...

You should read this and then read up on PB ports. They are a special port that has a choice of two internal sleeves. One sleeve is used if you are not going to use to use the PB port.
That NON-PB sleeve changes the control valve's internal flow to what it would be if there was no PB port at all. In that case, all fluid not being sent to the loader cylinders will be diverted to the return port and so back to the sump.
To make the PB port functional requires a different internal sleeve. When the sleeve makes the PB port functional, all flow not being sent to the loader cylinders goes out the PB port still under full pressure, and thence it is is intended to go to the next set of control valves. That is OK, because each set of control valves in the serial daisy string of PB-driven control valves also has a return port, and the final set of control valves can then use the final return port in the string to send the unused high pressure flow to the sump.

And there is our problem..... That PB port is probably under high pressure. So we cannot just remove that offending hose and block off the port or hose. First weneed to have the sleeve that depressurizes the PB port and THEN we can just plug that port and everything should work right.

But the problem is that those sleeves are specific to each model of loader valve. They are not universal. When you buy a loader valve with a PB port it comes with both sleeves.

If that is a stock loader valve, Hoye might have such a sleeve....but even he with his vast Yanmar knowledge might not recognize which particular sleeve he has in his hand.

Hmmm......It occurs to me that there at least one other possible way to trick that PB port. I'll give you a chance to work it out first. Let me know...
rScotty

 

[tc197]

Thank you rScotty! I’ll do some digging and report back.

 

[winston1]

If you have changed nothing and installed it on your new tractor the same as old then I suspect this 1/4"plug is your problem.
They make them in steel also but whatever material this is what you need. https://www.amazon.com/Brass-Fittin...aWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl&th=1

 

[rScotty]

If you have changed nothing and installed it on your new tractor the same as old then I suspect this 1/4"plug is your problem.
They make them in steel also but whatever material this is what you need. https://www.amazon.com/Brass-Fitting-Countersunk-Thread-Internal/dp/B081YDQ66X/ref=sr_1_1_sspa?keywords=1/4"+headless+pipe+plug&qid=1636889665&sr=8-1-spons&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUFFVU1SSjlCV0lBNjQmZW5jcnlwdGVkSWQ9QTA1ODc4NTFSSTBERlZWOFUyQVomZW5jcnlwdGVkQWRJZD1BMTAzNDA1NDFFQUhIMEdCNFJOQUcmd2lkZ2V0TmFtZT1zcF9hdGYmYWN0aW9uPWNsaWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl&th=1

Excellent! Winston, thanks for posting that illustration.
I just love those old artistic working view drawings. They explain so much.

That certainly is a good page. Is it from the OEM Yanmar workshop manual with the red plastic covers??

That whole picture is worth studying until understood. I agree that the owner should take a look to see whether that port-blocking screw is in there or not. It could be part of the problem.... and of a possible solution. Note that in the text that headless pressure blocking screw is improperly called out as a NPTF. But in the drawing and as you show it on Amazon the headless screw is actually a NPTM.

A couple of notes:
1. on the illustration, note that the directional valve assembly for the loader is only shown on the upper right in a schematic view. All other views are of the Hydraulic Cylinder Head.

2. The Power Beyond (PB or PBY) port D is shown as being active in that schematic of the loader valve. So in the schematic view there is pressure on the hydraulic cylinder head port A.

3. By the way, that schematic drawing of the directional control valve is an "old school" type of schematic drawing in which some internal return passages are not shown on the control valve schematic. In old school schematics some internal return passages of control valves were considered to be "obvious....."
So don't panic when you mentally move the control levers and find that where ou expect a return passage to show, the flow appears to just end instead of connecting to the return line.

So with the aid of this drawing, the OP may be able to change his hydraulics around so that he can use the PB and not have two competing sources of pressure. Will have to think on that.

Also, I was thinking back to yesterday's video where the OP shows a "T" in the return line. As a general rule, one never wants to "T" into a return line because it causes back pressure on both returns. I don't think that is his problem right now, but it is better to combine both returns into a "Y".

rScotty

 

[winston1]

It is from a copy of the original manual. I had this same arrangement on my old 2002D.