Hydraulic performance fade.

[RedDirt]

My Kubota SVL 75-2 operates fine until it is good and warmed up, then the boom and bucket will barley move. Fluid is clear, level is good, and the filter was just change. 3100 hours on the machine. I have talked with several Kubota shops and they all tell me they have never heard of such a problem like this. Just bring it on in and we will get you fixed is what they say. I wish that money grew on trees so I could pay them to fix it.

 

[WI_Hedgehog]

I'm not an expert nor do I own a track loader, though the problem sounds non-specific to track loaders and more of a hydraulic issue in general.

To me, it sounds like the boom/bucket hydraulic pump is likely worn; testing with a flow/pressure meter would show if that's the problem or not, but flow meters can be "a bit spendy."

If the boom/bucket pump is the problem the hotter the hydraulic fluid gets the thinner it gets and the more a pump will slip and create more heat, thinning the fluid...

This can happen with the wrong fluid (to save a few bucks "because I've never had an issue") or not changing the fluid at the prescribed intervals (to save a few bucks "because it looks fine").

 

[TheOldHokie]

My Kubota SVL 75-2 operates fine until it is good and warmed up, then the boom and bucket will barley move. Fluid is clear, level is good, and the filter was just change. 3100 hours on the machine. I have talked with several Kubota shops and they all tell me they have never heard of such a problem like this. Just bring it on in and we will get you fixed is what they say. I wish that money grew on trees so I could pay them to fix it.

As the Hedgehog said this sounds like a pump.problem.

You dont need a flow meter to test pressure. Buy an inexpensive ($20) hydraulic pressure gauge off Amazon. Once thd oil is hot connect the gauge to one of your hydraulic outlets, operate the conttols to send oil to that outlet, and see what your pressure is.

Dan

 

[WI_Hedgehog]

I think with only a pressure gauge the thought is to check the pressure after startup with the system "cold" and nothing else hydraulic running, run the system, then check it "hot" at the same RPM. If the pump pressure drops significantly it's likely the pump.

But, as mentioned I'm really, really new at hydraulics and still have lots to learn.

 

[TheOldHokie]

I think with only a pressure gauge the thought is to check the pressure after startup with the system "cold" and nothing else hydraulic running, run the system, then check it "hot" at the same RPM. If the pump is outputting a marked difference in pressure it's likely the pump.

But, as mentioned I'm really, really new at hydraulics and still have lots to learn.

You may be new to hydraulics but checking pressure while oil is still cold is a good thought.

Dan

 

[WI_Hedgehog]

You may be new to hydraulics but checking pressure while oil is still cold is a good thought.

You ought to see me fish a wire through the &*%-forsaken, no-space, tight-n-bendy-to-avoid-$#!+ realm of a BX.

(I can do that with hydraulic lines too, but M.F. the genius that designed the T&T kit is evil.)

 

[mikester]

Electrical problem?

 

[WI_Hedgehog]

Electrical problem?

Seat bypass, still in progress...
(family situation that is more important has taken priority)

 

[Runs With Scissors]

I had a transmission in a car I was working on one time do something kinda similar.

It would shift fine until it ran for a few minutes.

Then it would start acting up.

Turns out, there was so much crap in the pan, that it would take a minute for it all to get sucked up and block the filter.

By letting it sit for a while, the junk would apparently fall off and temporarily "unplug" the filter.

{it took the guy like 4 hours to drive it too the shop which was about 2 miles away }

 

[Fedup]

I think with only a pressure gauge the thought is to check the pressure after startup with the system "cold" and nothing else hydraulic running, run the system, then check it "hot" at the same RPM. If the pump pressure drops significantly it's likely the pump.

But, as mentioned I'm really, really new at hydraulics and still have lots to learn.

I have a number of pressure gauges, different ranges for different systems. One that I use a lot is a 3000 PSI gauge on a tee. one end has a male pioneer end, one end has a female coupler. The male end can go into most any tractor remote coupler. The machine's hydraulic hose goes into the female coupler. The system operates as always but the gauge is there all the time reading the pressure in the line whenever it's in use. (all day long, hot or cold) Sometimes it helps answer some questions.

 

[WI_Hedgehog]

I have a number of pressure gauges, different ranges for different systems. One that I use a lot is a 3000 PSI gauge on a tee. one end has a male pioneer end, one end has a female coupler. The male end can go into most any tractor remote coupler. The machine's hydraulic hose goes into the female coupler. The system operates as always but the gauge is there all the time reading the pressure in the line whenever it's in use. (all day long, hot or cold) Sometimes it helps answer some questions.

One of the generous members here offered to make me one of those (with a digital gauge that remembers peak pressure), and eventually it'll likely happen. First though I have to finish up the other projects on the machine that I started.

 

[TheOldHokie]

I have a number of pressure gauges, different ranges for different systems. One that I use a lot is a 3000 PSI gauge on a tee. one end has a male pioneer end, one end has a female coupler. The male end can go into most any tractor remote coupler. The machine's hydraulic hose goes into the female coupler. The system operates as always but the gauge is there all the time reading the pressure in the line whenever it's in use. (all day long, hot or cold) Sometimes it helps answer some questions.

What it does not answer is whether the cause of low pressure is upstream or downstream.

 

[Fedup]

What it does not answer is whether the cause of low pressure is upstream or downstream.

Maybe not, but if you plug a gauge into a coupler and deadhead it as you suggested earlier what does that tell you that this doesn't? What's upstream or downstream got to do with it?

 

[TheOldHokie]

Maybe not, but if you plug a gauge into a coupler and deadhead it as you suggested earlier what does that tell you that this doesn't? What's upstream or downstream got to do with it?

If ypu see low predsure with the gauge teed into a circuit you dont know which side of the circuit is dumping pressure.

Deadheading an outlet eliminates the cylinder as a possible source of pressure loss.

Deadheading the supply coming to the valve eliminates the valve and everything down stream of it.

That difference is important when troubleshooting a loss of pressure.

Dan

 

[whitetiger]

the filter was just change.

Which filter was just changed? It has 3 for the hydraulic fluid.
The fluid and filters are to be changed every 1000 hours.