KX080-3 hydraulics shut down engine

[rush creek]

I have a kx080-3 excavator when the bucket is open all the way the engine shut down same thing if I curl it all the way in. All filters fuel and hydraulic filters was change same problem I also feel that I'm not getting enough digging power. any help is be appreciated

 

[K5lwq]

When you say all the way down or up are you continuing to hold the valve open and that kills the engine or just the bucket being in that position kills the engine? When it dies, can you start it back up and leave the bucket in the position it died in and the engine will run?

 

[rush creek]

I continue to hold the valve open and the machine starts back up and if I holds it open again it will shut down.

 

[rush creek]

It only dose this with the bucket cylinder if I extend the stick cylinder it will not happen

 

[K5lwq]

I continue to hold the valve open and the machine starts back up and if I holds it open again it will shut down.

I was thinking that is what you meant. First of all I would not want to hold the valve open once the cylinders have reached full through. This dead heads the pump and can damage it to the point of no repair.

I suspect the relief valve is adjusted too tight and that is what is killing the engine. You need to get a pressure gauge and check the pressures on the system. The same thing could happen if you tried to lift to much weight. It should be set back within factory specs.

 

[rush creek]

I will check that tomorrow I should have a pressure gauge set somewhere . Do you happen to know offhand what the pressure should be

 

[rush creek]

I found my pressure test kit I will let you know the results tomorrow I think I will install a new relief valve also. Thanks again

 

[K5lwq]

Really need the manual for exact pressures but I see the working max pressure is 4000PSI.

 

[oldnslo]

Do you have a parts diagram or schematic for your machine? Curious since unless you have two pumps. All the the functions should be at same max pressure and cause engine to stall.

I looked at Messicks at the T version shows two pump or three pumps. Not sure if these where 3 difference options though

 

[K5lwq]

I saw the same thing. He really needs a service manual because pressures could be different at different points. There definitely would be more than one relief valve.

 

[ptsg]

I saw the same thing. He really needs a service manual because pressures could be different at different points. There definitely would be more than one relief valve.

Indeed. Plus it's a somewhat complex closed center system with a variable displacement pump. This requires a little bit of knowledge on these systems to do some basic troubleshooting.

I think the pump is not adjusting the stroke as it should and tries to pump the max flow at the max pressure which will kill the engine in no time. I just don't quite get why it's only doing it with the bucket cylinder/circuit.

 

[oldnslo]

K5lwq
Part of reason for wanting to a see a schematic is that with variable volume pressure compensated piston pumps there might not be a main or master relief valve since in theory the pump should de-stroke and not produce any flow before getting to a relief valve setting.
With pressure comp pump there are multiple control options and these can be challenging to diagnose without a schematic. When they work they are nice, when they don’t can be a multi step process to isolate the cause.

 

[Leejohn]

Does each spool have a adjusting relief valve??

 

[K5lwq]

K5lwq
Part of reason for wanting to a see a schematic is that with variable volume pressure compensated piston pumps there might not be a main or master relief valve since in theory the pump should de-stroke and not produce any flow before getting to a relief valve setting.
With pressure comp pump there are multiple control options and these can be challenging to diagnose without a schematic. When they work they are nice, when they don’t can be a multi step process to isolate the cause.

May very well be the case. I totally agree a schematic is necessary. But I would think if it will kill the tractor when holding a valve open it would do the same with the valve closed on a closed center system if it was a pump issue.

 

[oldnslo]

May very well be the case. I totally agree a schematic is necessary. But I would think if it will kill the tractor when holding a valve open it would do the same with the valve closed on a closed center system if it was a pump issue.

Agree unless there is some form of load sense system and this one section is not working properly. That is the good and bad about variable volume pumps, they provide a lot more control features but that also creates a lot more possible problems. Depending on age of machine could also have electric over hydraulic control so throw in a couple more variables.

 

[rush creek]

Good night all the machine a KX080-3 , V3800-Di-EU4 engine, serial #11745, year 2007. I won machine in a bid and I'm trying to work out the issues with it. It is a three pump machine and it do have a load sensing unit .
I change the main relief valve today , I think the machine has more power but it is doing the same thing. I also turn on the load sensing switch and when I extend the boom and stick out all the way the buzzer will alarm with the bucket empty so you are right I do have a problem there also. the switch is a little hard so I will order one from Messick tonight . I did not check pump pressure, I found my pressure test kit the other night and what a lovely kit it is with all the bells and whistles but not the adaptor to fit the Kubota machine. I will get a shop manual, saw a few on eBay. thanks for all the input