New owner of a YM1500D. No hydraulics.

[Ilmontgo-HT]

Hey everyone. I'm glad to have found this board and Hoye Tractor. A friend and I just went in on a YM1500D together. It has a loader. It has the loader valve with the two levers for that and a third lever for accessory hydraulics at the loader. The day before we saw the tractor, another person was looking at/operating it and apparently all the hydraulics just suddenly stopped working with no fanfare. Both of us being somewhat mechanically inclined and me having some experience with small Japanese diesels, we bought it as-is at a discount.

So with the engine running, there is no lift on either the loader or 3-point. The pump and lines aren't heating up at all or making any noise. The previous owner had recently had most hydraulic lines replaced and then he moved a lot of dirt successfully before listing it for sale. We did some checking (cracked open lines one at a time and cranked the engine) and there is no pressure or flow out of the pump. We haven't drained the hydraulic reservoir to check the pickup screen yet but will do so. The hydraulic oil is full on the dipstick.

We removed the pump to check the coupler. All mounting bolts for the pump were barely hand-tight, there was only half a gasket behind it and a tiny string of silicone. The nut that secures the coupler was also loose, backed off maybe a couple mm from being seated. The pump turns smooth and from what I can see down in there, the gears seem to mesh fine.

Do you think maybe the test-driver closed the 3-point lock-out at the wrong time and blew the pump? What <I><s></s>would<e></e></I> happen to the pump if someone did this? Mechanical damage? Is it possible that the coupler nut backed itself off and allowed the coupler to spin independently of the pump? We've been waiting on time and materials to put it all back together with the re-tightened pump coupler, new gasket and o-rings. Also, does anyone know the full hydraulic system capacity with a fluid change?

 

[winston-HT]

If your lucky it might just be the coupling key sheared on the pump. Need to pull it off and check. Sounds like it got dead headed.

 

[yzrmbsg-HT]

Full hydraulic Capacity is right at 4 gallons, just did my ym1500d a few weeks ago.

Agree with Winston, check the shear key.
https://www.hoyetractor.com/PROD/WK-522.htm

 

[Ilmontgo-HT]

Thanks for your replies @Winston and @yzrmbsg. My friend put it back together before I returned (it's at his place) so I didn't get to check the shaft key but I am fairly positive it's in there because I couldn't turn the shaft independently of the coupler when tightening the nut down. It also spun the pump seemingly fine. I overlooked that key in the parts diagrams so thanks for bringing it to my attention.

Yeah, I reckon you're right about getting dead-headed. After my friend put it back together he started the tractor and reports the loader lifted once before quitting working again. So today we drained the transmission/reservoir and pulled the pickup screen. It was completely covered with sludge, as well as the bottom of the transmission (like 1/2" - 1" deep around the pickup screen port). The screen also had a few small holes and a long rip. We filtered all the oil through an old reusable coffee filter to check for metal and store for flushing. The oil was golden-clear except the last half-gallon or so. There were some small silver metal flakes in the coffee filter but it was mostly a fine black clog-worthy mud. We flushed diesel through the transmission twice (poured in the fill and drained right out) and left it open to drain while we wait for a new pickup screen. I've never seen so much sludge in any vehicle/equipment...

I'm almost positive we didn't get all the sludge out of the transmission with those two diesel rinses so do you all have any suggestions for flushing the hydraulic system? I was thinking the following steps:
1. Install new screen.
2. Refill with old (but filtered) hydraulic fluid.
3. Put it all back together.
4. Start the tractor, verify function of loader/3-point lift.
5. Cycle the hydraulic functions a few times, get everything warmed up and circulating, drive around, etc.
6. Park and immediately drain the hydraulic fluid.
7. Remove, clean and reinstall the pickup screen.
8. Refill with new hydraulic oil and repeat steps 4 and 5.

 

[Ilmontgo-HT]

Oh, I think I misspoke, I meant to say we probably starved/cavitated the pump rather than dead-heading. If I understand right, dead-heading is when there is a blockage on the high-pressure side, right? A blockage in the supply wouldn't be as destructive?

 

[winston-HT]

The "sudden" stoppage of loader and 3 point is what makes it sound like a deadhead. No doubt clogged strainer could stop it but would not normally be "sudden". Sounds like you are on the right path in getting it cleaned up.

 

[Ilmontgo-HT]

Thanks Winston. We're hopefully working out the kinks.

 

[Ilmontgo-HT]

Thanks for your suggestions folks. It turned out to be the hydraulic pump shaft key after all. An $0.83 piece saved us $600 on the purchase price! Got it all back together with new fluid and pickup screen (and a few flushes as my partner installed the pickup screen backwards the first time) and it works like a dream.

I've noticed that the 3PH feedback arm is disconnected. Probably got dead-headed by the prospective buyer before us running with the 3PH all the way up, causing the pump shaft key to shear (thankfully not blowing the pump). Is there a specific procedure for setting the feedback arm on the 3PH? I assume one just gets it on there and adjusts it so there is no engine bog when the hitch is raised completely?

Thanks again for your help!

 

[winston-HT]

That is pretty much how I adjusted mine, just making sure it quit lifting before bottoming out the piston.

 

[yzrmbsg-HT]

Awesome! Glad you got working!

 

[Ilmontgo-HT]

Thanks!