Three point valve broken!!!

[rScotty]

In all fairness I believe a solid 95% or more of the Yanmars are plumbed the way we describe in our instructions. This is the first time I have heard of it causing a problem in almost 20 years. I suspect your loader valve was leaking due to the original TPH linkage problem which caused long term back-pressure (you said the only way your three point would stay up was by leaving the TPH valve in the lifting/relief position). That is just my theory but your situation is pretty unique and I don't think the loader plumbing was to blame.
Yes, we had those made by a local machine shop a few years ago.

It must have been about 1980 when my local Yanmar dealer decided he had enough of trying to get loaders to work properly in series with the tractor's own 3pt hydraulics with nothing more than the tractor's own hydraulics and a passive valveless diverter block. So he switched to doing it the correct way. He mounted all his loaders to be driven by a small outboard hydraulic pump coupled to the outer face if the crankshaft pulley. That way the loader hydraulics run separately from the tractor's internal 3pt hydraulics. I'm not sure if he came up with the idea or whether Yanmar did, but done that way the loader is fast, powerful, and doesn't have any cross-feed or valve problems.

I was at his shop one day and remember him throwing away a box full of those old valveless diverter blocks. I did keep one around for years just to remind myself that there is always a better way to do something....

For anyone having loader hydraulic problems like I see in this thread, a separate pump is the way to go. A lot of tractor guys stopped using that old "loader in series with the 3pt hydraulics" lashup shortly after it was introduced as a way to put cheap hydraulic loaders on the old Fords & Massey & IH tractors of the 1950s. For those tractors it was "cheap & better than nothing", and besides...without 4wd those old tractors couldn't do any more than lift and carry with their old pipe loaders anyway.

Yes, a diverter block can work, and so can a manual hydraulic valve. But an independent system does much better.
rScotty

 

[kenmac]

scotty, I see you have a kubota as well. I wish the loader worked as well on my yanmar as it does on my kubota.
On the kubota, there isn't much difference in lifting speed, or strength at idle than 20000 RPM's

Not the case with the yanmar. I have to turn up the RPM'S to get any speed at all out of the loader.
I believe this may be due in part to the PS getting priority fluid.

 

[kenmac]

The YM240 owner's manual shows that way, the simple series method and not PBY, as how to add a loader. There's lots of advice online saying this is wrong and will put excessive backpressure on the loader valve, eventually damaging it. Could be. My loader valve (third-party, not Yanmar) original from 1980 was dribbly when lifting maximum weight so I replaced it.

I saw a post somewhere saying a Kubota dealer stopped using the series method when they identified that as the cause for warranty repairs a few years after installation.

Apparently series plumbing is generally 'good enough' for casual use while PBY is preferable for a loader in continuous commercial use.

If yanmar shows it that way in the manual. I wonder why Dave mentioned yanmar having the fluid return filler port Like Hoye now has ?.

It has been a few yrs since I had the conversation with Dave so I don't remember all the specifics we discussed. It could have been that yanmar offered these if the customer had issued with a loader valve connected as you say they describe

 

[rScotty]

scotty, I see you have a kubota as well. I wish the loader worked as well on my yanmar as it does on my kubota.
On the kubota, there isn't much difference in lifting speed, or strength at idle than 20000 RPM's

Not the case with the yanmar. I have to turn up the RPM'S to get any speed at all out of the loader.
I believe this may be due in part to the PS getting priority fluid.

It sounds like the Yanmar has a some sort of restriction in the loader circuit....I agree that the problem could easily be in the priority valve giving priority to the PS.
Does anyone know an easy test for that priority valve? I never had to work on the priority valve on our YM336d (similar to your 3110D), so I know nothing about the innards of a priority valve. I do know that the YM336D OEM loader was fast and powerful, as was the power steering & 3pt. If they were stealing flow from one another it didn't see noticible. So at least we know it is possible.
Just for diagnosis, you might try reducing flow to the PS only. I'd probably do that by putting a small diameter insert into the PS feed line.

Of course anytime you get tired of playing with it and want to simply cure the problem and make everything work right regardless.... it is possible to add another hydraulic pump dedicated to the loader - just like my old Yanmar dealer preferred to do in my post above. In a dual pump system the loader upright often does double duty as a hydraulic fluid reservoir.
rScotty

 

[California]

On the kubota, there isn't much difference in lifting speed, or strength at idle than 20000 RPM's

Not the case with the yanmar. I have to turn up the RPM'S to get any speed at all out of the loader.
I believe this may be due in part to the PS getting priority fluid.

Similar here. The YM240's (no PS) loader works fine at any rpm, slightly slower below approximately 1200.

On the other hand the YM186D with power steering is a little frustrating. The low rpms suitable for approaching something slow and easy aren't enough to make the loader move at all. Presumably because the PS is getting all the flow.

But also at low rpms, the PS is taking so much pump output that turning the steering wheel for an extreme turn will stall the engine. It is necessary to back off to a less sharp turn.

Everything works better, as it should, after revving up to an intermediate rpm that is unnecessarily fast for just movement. I wish the hydraulics could power the loader and PS properly at low puttering-around rpms.

 

[kenmac]

Similar here. The YM240's (no PS) loader works fine at any rpm, slightly slower below approximately 1200.

On the other hand the YM186D with power steering is a little frustrating. The low rpms suitable for approaching something slow and easy aren't enough to make the loader move at all. Presumably because the PS is getting all the flow.

Well, it's nice to know I'm not the only one with a slow loader at lower RPM's.
You describe the exact problems. I deal with

I wish there were a way to reduce flow to ps so that the loader would operate faster. I believe all this is done through the diverter valve, but not positive..

I often wonder how they do it on newer tractors with ps, Perhaps higher flow pumps, plumbed differently, etc, ?

I do know the kubota uses rack and pinion style ps. the old yanmar style factory ps ma take more flow to function than the newer systems