Main pump problems.

[Taat]

Hello masters!
I have an issue with a Kawasaki K3V63DTP pump. One piston pump is weak and I have trouble learning if the issue is in the pump internally or in the regulator. To check if the pump is internally worn I checked for internal leakage and performed the case drain test, which came out at about 25l/min of flow. Now each pump has a flow rate of 106.6l/min and applying that to the rule of thumb that axial piston pumps and motors case drain flow should be 5% of maximum pumps flow (4.5l/min in my case) I can say that there is significant leakage and wear in my pumps internal components.
But looking at the schematic I can see that the pilot pumps drain is connected to the main pumps. And looking at the pump the case drain of the main pumps is coming from the PTO unit which is connecting the pilot and sub pump.
So with that information I guess the pilot pump is flushing oil to the case drain, contributing to the overall flow of the case drain?
My next step is to swap the regulators to see how the pressure would then behave at the main pumps, but I want to know first how much of case drain is expected from this pump with all this information.
Let me note that the pump doesn’t generate noise, heat or vibration so I am leaning more towards the regulator being the culprit of low pressure-flow.

 

[Mick-the-fitter]

Hello masters!
I have an issue with a Kawasaki K3V63DTP pump. One piston pump is weak and I have trouble learning if the issue is in the pump internally or in the regulator. To check if the pump is internally worn I checked for internal leakage and performed the case drain test, which came out at about 25l/min of flow. Now each pump has a flow rate of 106.6l/min and applying that to the rule of thumb that axial piston pumps and motors case drain flow should be 5% of maximum pumps flow (4.5l/min in my case) I can say that there is significant leakage and wear in my pumps internal components.
But looking at the schematic I can see that the pilot pumps drain is connected to the main pumps. And looking at the pump the case drain of the main pumps is coming from the PTO unit which is connecting the pilot and sub pump.
So with that information I guess the pilot pump is flushing oil to the case drain, contributing to the overall flow of the case drain?
My next step is to swap the regulators to see how the pressure would then behave at the main pumps, but I want to know first how much of case drain is expected from this pump with all this information.
Let me note that the pump doesn’t generate noise, heat or vibration so I am leaning more towards the regulator being the culprit of low pressure-flow.

20 ltrs pm is far to much even if the pilot pump dumps into the return! Have you checked case drain P1 against P2?

 

[Taat]

20 ltrs pm is far to much even if the pilot pump dumps into the return! Have you checked case drain P1 against P2?

No I haven’t, just the combined on the PTO unit, I will need to get some more fittings to do so. I guess I should try that also…
Any other method to check if the problem is the pump or the regulator? Can I make any adjustment on the regulator of the weak pump to see how the flow-pressure would behave?

 

[Taat]

This is a screenshot from my manual. Can I try to adjust this screw and see how pump responds, or is this not reliable and should leave the set screw as it is?

 

[Mick-the-fitter]

If possible I would change the hoses from P1 to P2 first and see if you get the issue on the other side!

 

[Taat]

If possible I would change the hoses from P1 to P2 first and see if you get the issue on the other side!

I already did that. Thats how I narrowed down the problem to the pump or the regulator. I got weak track on the other side and some other weak functions which otherwise work fine on the original configuration of outputs.

 

[Mick-the-fitter]

Ok so if all the original end stops and ARV’s are set as original then it’s going to be pump off and strip

 

[Taat]

Ok so if all the original end stops and ARV’s are set as original then it’s going to be pump off and strip

Okay, so I see you are pretty confident the pump is the problem. Would the regulator swap still be sensible? In between the swapping I was thinking of sending them to a hydraulic shop to have them checked. Or would that be wasted time and money?

I tried to adjust the flow rate control as I mentioned above. I have set the screw so that the flow would increase by 15l/min, but that didn’t do anything and output pressure was the same, so I just set it back as it was before. Is there anything to learn from this?
And when observing the output pressure on this faulty pump when l pull the arm function halfway it gets to about 300bar and doing full pull it drops to about 250bar while 350bar is the spec. And when the pressure is at 250bar if I use the bucket function simultaneously, then the pressure at that faulty pump jumps to 350bar. Does that make any sense?

Anyway I myself suspected that the pump was the problem, I just hoped that maybe it would be possible that the regulator would be at fault. That would be easiest to just replace and be done with it…

 

[Mick-the-fitter]

So if you change P1 to P2 do you get the same pressure results?

 

[V8Druid]

So if you change P1 to P2 do you get the same pressure results?

presume you're considering a poorer flow rate Mick ??

 

[Mick-the-fitter]

presume you're considering a poorer flow rate Mick ??

Either pressure or flow! Some sort of difference, if I remember rightly the pumps are mounted back to back essentially the same pump in reverse! Have you measured flow at X1 hammer line?

 

[V8Druid]

Either pressure or flow! Some sort of difference, if I remember rightly the pumps are mounted back to back essentially the same pump in reverse! Have you measured flow at X1 hammer line?

OP said he's swapped the pumps around and got a weaker performance change from side to side as swapped

 

[Taat]

Well I haven’t checked the pressure in the switched position. I was anxious about having the hoses switched because the machine was pretty much inoperable when switched.

In the switched position left track got weak but traveling was almost impossible. The machine just wanted to turn in its place because of how weak it was on one side. In addition to that the boom hardly lifted and bucket was slow in both directions.

In original setting of outputs the most noticeable is the right track of course. When traveling straight on level ground I could say it’s 80% weaker compared to the left. Traveling up on an incline maybe 60% and stops turning before the left one if extreme slope. With that the arm-stick pushing almost has no power. No other noticeable weak functions.

So I guess the pressure and flow would be lower if measured when the outputs are switched.

 

[Taat]

Either pressure or flow! Some sort of difference, if I remember rightly the pumps are mounted back to back essentially the same pump in reverse! Have you measured flow at X1 hammer line?

I’m sorry I didn’t see this message. No I haven’t. Is that the hydraulic breaker line? Do I need flow meter to do that?

 

[Taat]

So all in all. If the pump is the issue I think I will buy a new one from Handok in Korea. I have been in contact with the two that have them mounted on TB 1140 like mine and are very satisfied with it. Adding up the cost of estimated rebuild adds up to almost the cost of this pump and if choosing to use the OEM parts maybe twice the price of this pump. It won’t be the original Kawasaki pump but for an almost 13,000 hour machine which will be used only on a farm and some landscaping will probably be okay. What do you guys think about this option?

 

[V8Druid]

So all in all. If the pump is the issue I think I will buy a new one from Handok in Korea. I have been in contact with the two that have them mounted on TB 1140 like mine and are very satisfied with it. Adding up the cost of estimated rebuild adds up to almost the cost of this pump and if choosing to use the OEM parts maybe twice the price of this pump. It won’t be the original Kawasaki pump but for an almost 13,000 hour machine which will be used only on a farm and some landscaping will probably be okay. What do you guys think about this option?

you pays yer money and takes yer chance ...... but .. buy cheap, buy twice springs to my mind

 

[mart1602]

what area of the country are you? i know a really good guy to rebuild pumps in south wales

 

[V8Druid]

what area of the country are you? i know a really good guy to rebuild pumps in south wales

WTF is Zda????????

 

[Taat]

you pays yer money and takes yer chance ...... but .. buy cheap, buy twice springs to my mind
View attachment 61394

I am aware of that, but original parts are very expensive in my country so even the people who are in construction business often search for aftermarket parts.

 

[Taat]

what area of the country are you? i know a really good guy to rebuild pumps in south wales

WTF is Zda????????

View attachment 61395

I am from Slovenia actually… I don’t know why it says that, I don’t even remember putting in a location when setting up the account.