kubota kx71

[gordon macritchie]

hi need some advice on a 1997 kubota kx 71 i have bought

hydraulics are very sluggish when operating the machine, dipper arm is very slow, is there a button or switch for speeding things up or are they supposed to be like this

the radiator cap has started leaking, looks like the rubber seals have perished, cant seem to find one online, does anyone know if one of a similar machine or tractor etc will fit

[2414.ginger]

Could it be that a new filter and oil will make a different machine out of it?
Are all things equally slow, or are some slower than others, or are you new to diggers and not really sure?
Someone better qualified than me will be along soon with some more sensible advice I'm sure.

Forgot to say welome Gordon.
And see I told you someone would soon resond.

[v8druid]

greetings and welcome Gordon ..... is every motion dog slow ?????

what sort of engine revs are you running at ?

lots of options to look at/consider ... some easy/cheap ..... some horrific/OMG expensive

Hydraulic oil pick up strainer could be blocked in the tank .... oil return filter to the tank, could similarly be blocked.

is this a servo op. machine ? I'm not familiar with the Kubs.
Muz'll know for sure and is probably the best man here for advice on this.

worst case scenario is ****ed pump .... or knackered servo pressure pump.

some pressure gauge testing'd be a good point to start, to see what you've got in the way of pressures.
must be some test ports in the circuits somewhere ................ Muz???

[gordon macritchie]

have had diggers before and they all seemed faster than this one, dipper arm seems to be worse, its servo controls, will change oil and filters and take it from there, is it just the one hydraulic filter? am i right in thinking there is a strainer on the pickup pipe

[v8druid]

have had diggers before and they all seemed faster than this one, dipper arm seems to be worse, its servo controls, will change oil and filters and take it from there, is it just the one hydraulic filter? am i right in thinking there is a strainer on the pickup pipe

Yeh strainer on the pick up pipe in the tank ....... also a servo filter too - usually takes some finding and could well be an issue ... what sort of hours on this tool Gordon?
could have a seal set bypassing on the dipper? how does it hold position?
any check valves on it?
crap in a valve?
even faulty servo stick seals?

First and foremost ..... get some pressures checked, to make certain that the pump is making it in the first place

[gordon macritchie]

just under 4000 hours
found return and strainer filter on ebay, but not seen a servo filter anywhere
holds position perfect
not sure about check valves

[v8druid]

just under 4000 hours
found return and strainer filter on ebay, but not seen a servo filter anywhere
holds position perfect
not sure about check valves

Hmm ..... as said servo filter will take some locating .... most likely in servo solenoid control block ..... where ever the dead man switch is connected to either trace back from that, if poss, or from servo pump forward on plumbing

again as said ...... best and first test/indicator is get some pressure readings .... will tell you A LOT ..... can spend a lot of time faffing and produce no results if pressures aren't there to start with.
what sort of pumps on there .... fixed or variable displacement .... if variable, check pressure at the load sensing line ..... no/low load sense = no/low flow rate ..... pump won't be upstroking ..... trust me .... been there, got the tee shirt. have a look in my thread ... 'bout Aug./Sept. last year ..... and it's a bugger to diagnose

[Muz]

Dont think a 71 has a servo filter, I assume is a dash 1 ? IIRC it has a separate gear pump that pressurises the servo circuit which could be faulty , and IIRC there is only one suction strainer in the tank. While since Ive owned one right enough As V8 mentioned, a pressure test will tell you a lot about whats going on .. oh and welcome also

[gordon macritchie]

yes its a dash 1, hopefully get the oil changed and filters next saturday take it from there

[v8druid]

before you go chucking money at it .... get some pressures .... please!!

If it is a pump issue ..... and you do all the changes ... you'll only have to do it a second time

Have a look at the return filter for anything metalic/FBs ..... unless it's a canister ..... if it is and it's heavy, would be worth opening it up to see what it's caught

this is of course worst case scenario, but if it's as slow as you say ..... I'd be opening that up/eyeballing the filter as a first port of call ..... after getting some pressure readings

is it fixed or variable displacement pumps on there?

[Muz]

before you go chucking money at it .... get some pressures .... please!!

If it is a pump issue ..... and you do all the changes ... you'll only have to do it a second time

Have a look at the return filter for anything metalic/FBs ..... unless it's a canister ..... if it is and it's heavy, would be worth opening it up to see what it's caught

this is of course worst case scenario, but if it's as slow as you say ..... I'd be opening that up/eyeballing the filter as a first port of call ..... after getting some pressure readings

is it fixed or variable displacement pumps on there?

Triple gears IIRC

[v8druid]

Triple gears IIRC

OK so no load sensing to give issues then and presumably a pump for separate motions ..... so if all motions slow .... points to pick up filtration/supply problems from tank to pumps or if pumps/engine are loaded all the time blocked return ??

or

Pipe collapsing from tank to pumps, either due to deterioration or blocked pick up strainer

or

servo pressure's down and not opening main valves properly, to give full flow

or

MRV blowing off ... crap in it or busted spring / damaged seat ... or plain old stuck/seized partially open ?

really, REALLY wants some gauges plugging into the lines to see what's what in the way of servo and main pressures

[v8druid]

this what we're talking about Muz / Gordon ??



from memory .... long time since I sat in one of these .... they need to be run pretty hard ?

is it down on power as well as speed Gordon?

[gordon macritchie]

thats the same machine, power seems ok,
have been told by an old fitter to mix engine oil in with the hydraulic oil, says it will improve things has anyone heard of this been done

[Muz]

thats the same machine, power seems ok,
have been told by an old fitter to mix engine oil in with the hydraulic oil, says it will improve things has anyone heard of this been done

Not on my watch