Hyd Pump brand

[Fracture]

I've been having progressive weakening of my hydrocs since I purchased my '13 Kioti DK55. After it's warm it barely functions and everything (except steering) takes 5 times as long as it should. Sometimes it flat out can't do the simplest thing (raising empty FEL) without 3000 RPM. Been to dealer 3 times but they just keep checking it's cold pressure and "everything is normal". I've told them it only happens when warm and Kioti dealer literally said "I wouldn't even know how to test that". So needless to say, I'm not relying on them for a fix. I figure it's a poor pump and/or design that's getting out of spec. What I'm wondering is what pump/brand should I be looking for? There seems to be a few replacements available but I don't want to spend time and money and wind up with the same problem. Thanks for any help.

 

[rScotty]

If this is a simple pump system with a proportional valve for the power steering... and If it has pressure cold....AND the power steering still works when it is warm, then I would not be looking first at the hydraulic pump. It sounds like that pump is working. If so, chances are that it will work when hot just as well or close enough.

If you want to be sure the hydraulic pump is working when hot, you need to find a dealership that has a hydraulic flow meter. Most do not. A hydraulic pressure/flow meter combo is the hydraulic equivalent of an electrician's VOM for hydraulic systems.

To me it sounds more like the pump is working but the flow is being diverted back to the sump.
If you want to do it yourself, start by looking at the FEL control valve assembly - specifically at the relief valve in that valve assembly. Then I would do the same at the power steering relief and the 3pt lift relief valves.

You can also check the return lines for all the valve assemblies tall of those return lines to see if that is where the flow is escaping.

Do you have a hydraulic schematic for your tractor?
How is the 3pt lift working?

rScotty

 

[oldnslo]

Is the pump visible and accessible? If yes use a thermal heat gun or your hand to see if the pump housing gets warm quickly compared to inlet line. If yes then potential is bypassing internally. If no then need to check next item in the system. Some tractors have a diverter block usually mounted on the tranny housing. There have been a couple reports of components in these failing.

If dealer can check pressure cold I am hard pressed to understand why they could not check it when warmed up.

 

[Fracture]

I do have a schematic for the system. I can see the pump, probably inlet/outlets. Same problem with 3pt & rear remotes. On schematic, the steering gets flow priority (if reading right) and hasn't been a significant problem. How do you "check" a valve assembly or diverter block? I'm trying to do it myself because the dealer is no help and I don't really know who else to ask. My dealer also sells heavy equipment, so I figured they would deal with hyd pressure/flow issues regularly. Like I said, service mechanic literally said he "wouldn't know how to test it". Very infuriating but I can't wait on them, so I thought I'd try something myself. How do you find a hydraulic specialist? Would this be someone other than an equipment mechanic? Thanks fellas

PS: 2011 Kioti DK55

 

[rScotty]

I do have a schematic for the system. I can see the pump, probably inlet/outlets. Same problem with 3pt & rear remotes. On schematic, the steering gets flow priority (if reading right) and hasn't been a significant problem. How do you "check" a valve assembly or diverter block? I'm trying to do it myself because the dealer is no help and I don't really know who else to ask. My dealer also sells heavy equipment, so I figured they would deal with hyd pressure/flow issues regularly. Like I said, service mechanic literally said he "wouldn't know how to test it". Very infuriating but I can't wait on them, so I thought I'd try something myself. How do you find a hydraulic specialist? Would this be someone other than an equipment mechanic? Thanks fellas

PS: 2011 Kioti DK55

Sounds to me like you may be able to figure it out. You will probably have to do so yourself.
Read on to see if you want to do so.

Start by posting whatever you have for a hydraulic schematic so we can see it.

I understand your frustration. Diagnosing hydraulics has the same problem everywhere. Hydraulic theory and repair is complicated and a lot of it isn't intuitive or visible like mechanical things are - or easy to measure or test like electrical things are.

That's no excuse, but it explains why hydraulics isn't taught in regular mechanical courses.
A mechanic who puts in the time to learn hydraulic systems - and it can take a year and some schooling - can make twice as much working for industry or aviation instead of doing "wrench bending" type of work. So you won't find him at a small time tractor dealerships.

You will find him at an industrial heavy equipment dealership that sells Yellow JD or Cats. And he will have an the proper test tool: including the mysterious full fow adjustable industrial flowmeter that cost a thousand or two, along with a box full of adapters that he can use to insert his flowmeter into your hydraulic line. In there he will vary the resistance to flow, measure the resulting pressure and flow rate, and tell you pretty quickly where the problem is. It will take about an hour.

So one way to attack your problem is to find a shop where they have a hydraulics guy who has a flowmeter setup. You ought to at least give that a try.

The other way is to use your own skills plus some TBNers here, buy a few special tools, a pressure gauge test kit (amazon), some 5 gallon buckets. and some cheap fluid to come up with messy workarounds to try to do the diagnosis at home. That can be costly the first time replacing parts that don't need it because of not having any way to test them. But it's what most of us do.

rScotty

 

[Harry in Ky]

As I see it from parts lists you have a two stack pump. One section for steering and one for hydraulics. I don't see a flow divider anywhere. The piping shown looks like it could be separated easily enough and a flow meter installed to end all the guesswork as to whether or not the pump section in question is up to snuff. If your "dealership mechanics" can't do that, you probably should consider doing business somewhere else.

 

[Leejohn]

Make sure your 3pt is not all the way up.

 

[rScotty]

Hello Harry. So the pump for his Kioti DK55 is a two stacker? A piggyback pump? Right....In that case it wouldn't need to have a flow divider or proportional divider.

In that case, the hydraulic failure could be as simple as an air leak in the line or fittings that go from the sump or filter and then up to the input to the primary pump.

That sort of suction line air leak into the fluid is actually among the most common type of hydraulic failure in tractors.
It also meets the OP's condition of being progressive over a long time, and of losing pressure the longer that the tractor runs - so it seems like it is being caused by heat. Plus ultimately a suction leak necessitates going to full RPM to get any hydraulics at all.
And of course it wouldn't affect the steering because that is a different pump.

A diagnostic test for a suction air leak is that the hydraulic fluid itself will be full of millions of tiny bubbles instead of being clear. So look at the dip stick and then drain a quart of hydraulic fluid out into a fruit jar after running it until you've "warmed it up" and see what the fluid looks like. Normal trans/hydrualic fluid is clear and transparent. If it is opaque or cloudy and then clears up when it sits overnight then you are on the track of a suction air leak.
And if the fluid is old enough to have gotten water from condensation or weather, then the fluid you drain out can look like a frothy milkshake. Again, it will clear up a lot if it is let sit overnight. But in that case the fluid needs to be replaced as well as the suction air leak found.

The other test for a suction air leak is that the exterior of the pipe or hose will be wet with fresh oil. Look around the mounting base of the hydraulic filter too. Normally a suction air leak does't leak out into the world when running (it leaks air IN, not fluid OUT) - but it will leak out when the tractor is just sitting. So crawl under and look for a suspiciously wet oily hose or pipe that runs from sump to filter to pump inlet. If a hose, it may have a hose clamp, but tightening that is a short term fix. Long term is to find where the air is getting in - often a hose or gasket - and fit a new part. A nice cheap fix.

This is exactly what is meant by "messy backyard hydraulic tests" when you don't have real hydraulic test equipment.
Luck,
rScotty

 

[rScotty]

Make sure your 3pt is not all the way up.

that's right. Some tractors - not all - have a full flow relief valve that actuates when the 3pt hitch arms are all the way up. Especially if they are stuck over center all the way up. That relief prevents blowing up the top of the 3pt, but it means that nothing else in the whole hydraulic system has any flow or pressure - except the power steering which is supposed to be made to work when everything else fails.

 

[Harry in Ky]

Why would it not affect steering if it's a common suction causing the problem. That theory holds no water in my book. I'm betting he has a tired pump section, probably due to some sort of issue way back in time. Like a remote valve or three point control stuck on and gone un noticed for a bit too long. Maybe just normal use but a LOT of it. Who knows, but the flow meter is the proof. Anything less is just a guessing game.

 

[rScotty]

Why would it not affect steering if it's a common suction causing the problem. That theory holds no water in my book. I'm betting he has a tired pump section, probably due to some sort of issue way back in time. Like a remote valve or three point control stuck on and gone un noticed for a bit too long. Maybe just normal use but a LOT of it. Who knows, but the flow meter is the proof. Anything less is just a guessing game.

I admit I am guessing. We don't have a choice yet. So far we don't have a flowmeter and the OP hasn't found anyone who does. Also, the OP has not posted his hydraulic schematic - and until he does we can't know for sure how his tractor is plumbed.
I don't think that shouldn't keep us from speculating. Speculation is fun and also a good way to learn..

Whether a suction air leak would affect steering or not depends of whether the two pumps are using a common suction circuit or two independent ones. You assume they are common; I assume the pumps have separate suction circuits. The argument for common is simplicity, but if so why use two pumps?
I chose independent suction circuits because to me that is the best way to design for what the tractor needs to do.

I think of it this way: It is far more expensive to build two pumps - even given that they have a common drive - than to do the same thing the other way, which is to build one pump and then feed its output into an inexpensive diverter valve to divide the flow into two separate flows post-pump.

So there must be advantages to go to the complexity and expense of two pumps. The advantages I see are twofold: to make the steering system more failure proof and to keep one downstream circuit demand from stealing all the flow from the other. The best way to do both of those is to make it so that both pumps have their own independent suction path to their own dedicated input port.

I assume that the Kioti is that sophisticated partly because that is the way that other tractors are made.

rScotty

 

[BackRoad]

Respectfully, you two guys are amazing...simply amazing!!!

 

[Harry in Ky]

I admit I am guessing. We don't have a choice yet. So far we don't have a flowmeter and the OP hasn't found anyone who does. Also, the OP has not posted his hydraulic schematic - and until he does we can't know for sure how his tractor is plumbed.
I don't think that shouldn't keep us from speculating. Speculation is fun and also a good way to learn..

Whether a suction air leak would affect steering or not depends of whether the two pumps are using a common suction circuit or two independent ones. You assume they are common; I assume the pumps have separate suction circuits. The argument for common is simplicity, but if so why use two pumps?
I chose independent suction circuits because to me that is the best way to design for what the tractor needs to do.

I think of it this way: It is far more expensive to build two pumps - even given that they have a common drive - than to do the same thing the other way, which is to build one pump and then feed its output into an inexpensive diverter valve to divide the flow into two separate flows post-pump.

So there must be advantages to go to the complexity and expense of two pumps. The advantages I see are twofold: to make the steering system more failure proof and to keep one downstream circuit demand from stealing all the flow from the other. The best way to do both of those is to make it so that both pumps have their own independent suction path to their own dedicated input port.

I assume that the Kioti is that sophisticated partly because that is the way that other tractors are made.

rScotty

If you look at the parts breakdown for this model you can see very quickly how the pump and lines are laid out. It will answer many of your questions and narrow down your speculations.

 

[rScotty]

Respectfully, you two guys are amazing...simply amazing!!!

Luckily, there are a number of guys on TBN who know hydraulics well enough to enjoy helping.
It's also a good way to learn more and get involved with interesting problems - all without tracking oil into our own workshop. The downside is that too often we don't get to hear how it turned out.

Right now I think we've hit the "how it works" part hard enough for a start.
I'm curious to see what the OP decides to do.

rScotty

 

[NYlumberman]

I’m not so sure that a leak on the suction side of the pump would be oil temperature sensitive. That fact sends me toward a valve seat or a spring. I had a Gresen bank of valves with crack in one valve body that made me look stupid for a week before I finally found while replacing the whole 4 valve assembly. All education is expensive.

That said the advice on establishing pressure and flow is spot on.

 

[rScotty]

I’m not so sure that a leak on the suction side of the pump would be oil temperature sensitive. That fact sends me toward a valve seat or a spring. I had a Gresen bank of valves with crack in one valve body that made me look stupid for a week before I finally found while replacing the whole 4 valve assembly. All education is expensive.

That said the advice on establishing pressure and flow is spot on.

I don't think we know if oil temperature has anything to do with the problem. The problem might be just from running and completely independent of temperature.

 

[Fracture]

Thanks for all your input. Yes, it's a 2-part pump. I did a thermal check. The 2 sections of the pump are only 3-5 Celsius different (54C & 49C), while inlet tube was 42-46 C on average. Outlet tubes temps were about what was on the respective pump side. I'll post schematics ASAP. I'm working through holiday weekend, so it may be a minute. I think I'll look for Cat (or similar) shop to get flow tests done for starters. I'm always up to learn new mechanics and I may wind up going this way if I can't find help locally. I'd love to not go back to my dealer, but unfortunately, they're the only place to get OEM parts.

 

[oldnslo]

Fracture
Were you operating the loader when you performed the temperature test? If yes my guess is the pump is fine and problem is elsewhere. If pump is slipping so much nothing moves it will heat up fairly quickly.

 

[Harry in Ky]

And so we have another opinion here. Maybe someday we'll find out what the problem was.

 

[Fracture]

While I'm in my a search for equipment mechanic, here's my schematics if anyone thinks they can help. Checked temps with surface reader, but wasn't directly running FEL (or any other hydraulics). Pulled into barn and only running at idle.Had just used tractor with FEL/PTO. It was warm, but not at the point where it usually poops out. Just didn't have time or need for heavy use that at the moment. I'll recheck after an hour of heavier use asap.