Kubota KX41-2S issues

[Anto Modded]

Hope this is in the right section but im have some problems, please ear with me if i dont explain right but ill try my best.

I have a 2002 Kubota KX41-2S with 1200 hours on it. About 2 weeks ago i was doing some digging when i noticed the boom dipper arm would not come in or out on its own, but would come in and out only if i was doing 2 controls ( like slew left or curl the bucket etc) Also one of the tracks was traking when i tried to move the dipper arm on its own. After 2 minutes or so the machine came right. I checked hydraulic fluid and it was grand and the valve chest ect seem dry and no syashed hose's or leaks.
Yesterday 4 weeks later it happened again only worse.......... the dipper arm wouldnt go in or out on its own and the boom arm wouldnt go in or out on its own, but when worked together it was grand. Also if i tracked backwoards(away from the blade its grand) but when i went to track foward (towards the blade) the levers felt very stiff and hard to push like something was blocking them. Again after a few mins it worked grand. But this problem has me worried. Anyone ever have a similar problem, father is a mechanic. I found an online manual with the hydraulic setup as i take it is that. Going to change the hydraulic oil and filter, see if it helps but im only stabbing in the dark at this.
Any help would be great and sorry for the long post.

 

[strott]

Can't see it being a hydraulic oil issue, if most of the time the machine runs fine and the oil level is within the recomended levels.

Does the engine strain when the said issues occur? Could indicate a blockage/loose debris (maybe from the valve block itself) is blocking the valve from opening or restricitng flow.

I would suggest next time it happens if possible lift up the floor and expose the valve block to see what is/isn't moving!! The problem may be obvious or easier to diagnose (the only time I have had a similar issue is when the tracking levers wouldn't let the tracks fully counter rotate but would track forward and backwards as normal - this was down to seizing in the bottom of the track levers so all that was needed was a bit of grease and persuassion!! this was on a KX41-3 by the way)

Looking forward to hearing the result of any findings.

 

[Anto Modded]

Engine doesnt strain when this happens. Ive lifted the floorl off when this appened and everything was ok. Could be dirt in the hydraulic system im really not sure. I thought maybe a solinoid if it has any but for the track leavers to both go stiff only in one directo has me baffled unless there is two pumps or something that works half the controls. Its very annoying cause its a great little machine which i love working.

 

[strott]

If the 41-2 runs 3 gear pumps then yes it is likely that each track gets its own pump feed but if the stiffness is only in one direction then I can't see how that would hint at the problem being the pumps.

It maybe the servo controls and their oil feed causing the problem - could they be loosing pressure/leaking hence making movements of the controls hard or slow when operating more than one function?

 

[Anto Modded]

The hydraulics are dry, no leaks anywhere. I dont know how many pumps thay have to be honest, but a friend had a jcb 801.4 and it was ''parilised'' down one side and he replaced the hydraulic pumps (3 in total) twice in one year. Later to realise it was a '' like cap, 2 of them on the pumps. Hard to explain they were like a cap with a little chain on a valve maybe. Worked the digger yesterday with no problems at all, oe thing i never touched was the fast tracking pedal ?.............. found these diagrams http://www.messicks.com/Kubota/KX41-2S-SERIES.aspx which are detailed. Will change the fluid and filters and try see if there is valves that might stich as looking at the valvechest everything is worked on levers. Its a mind boggler that i have to solve. Buying a kx-008 next week. I will take some pics of the hydralics ect as it all seems perfect. I can video ot either just it only happens the odd time

 

[strott]

So do I take it that your friends 801.4 had caps/valves on the pumps which somehow closed causing a similar issue?

Its the stiffness which makes no sense because lets say that one of your pumps is intermitantly failing then your hydraulics would fail to work e.t.c but you should still be able to move the levers e.g you can push the track levers forward and back easily with the engine off - when there is no hydraulic oil flowing!!

I have no idea whats up!!

Good luck!!

You'll love the KX008 as well, get some pics up when you get a chance.

 

[Anto Modded]

going to clean the tank and the valve chest incase of dirt. Have a Hinowa but the kx008 is replacing it. Was told when a digger is used much it can get air in the hydraulics and cause it but i dont believe it. I'll find the problem eventually

 

[AtlasRob]

going to clean the tank and the valve chest incase of dirt. ............. I'll find the problem eventually

Have you ever changed the hyd oil filter on this machine?

I would go with the assumption that you have a foriegn body in the main spool block. Be it a tiny bit of metal, or rubber, cant see it being dirt unless you have recently had a pipe replaced or added oil.

You say everything appears dry, so hopefully no oil leaking out one would hope no dirt is getting in.

I favour a foriegn body sticking a spool as operation of another service at the same time seems to ease the problem ( if I have understood correctly ) this would suggest ( with my very limited understanding of spools ) that although a spool is not getting its full travel to align perfectly with the gallery required, activating another valve is letting oil threw from a different gallery. BUT I could be talking out my rearend.

I cant see any other way that a machine can operate perfectly for a few hours, days or even weeks then have a problem on a different service.

My machine had a gear selection problem before I even got my hands on it.
Susequently a valve block was replaced. I then twice had a spool stick. First time I could not get my quick hitch to release, 2nd time a month or so later I could not select low range. BOTH times a tiny piece of swarf was found in the respective spool. No metal particles have shown up in subsequent filter changes.

on edit, been and reread your first post.

I would strip the valve block! BUT I am not recommending you do this without some proffessional advice.

I am sure Atcoequip and one or two other proper spanner jugglers will have some much better input.

 

[Anto Modded]

AtlasRob.......thanks very much for the input. Machine has 1200hrs on it. Fluid was changed in the motors an serviced but hydraulic oil was never changed and the hydraulic filter was never changed. Looking at the diagram there is 2 hydraulic filters, so i will get the 2 filters and change the fluid. Your suggestion on the valvechest to be taken out is probly the best option but i will change the fluid and filters and do it again after a few hours just to try flush it out. Hoses have never been replaced on the machine. I will take the filters out on monday, one is in the tank judging by the diagram and the other is somewhere close. I will take a few photo's too and post them up. Thank you for you advice, much appriciated

 

[AtlasRob]

Machine has 1200hrs on it. ........ but hydraulic oil was never changed and the hydraulic filter was never changed. Looking at the diagram there is 2 hydraulic filters, so i will get the 2 filters and change the fluid.

Dont rush to change the oil, check what the spec is and get it sampled first.
Its probably due at 2000hrs which could give you another years service depending on how much you use it.
Of course on that machine its probably not too expensive, on my duck I am looking at several hundred pounds and £80 a time ( 500hrs) for the filter.

Once you have the filters changed open the old one up to see what they reveal. Literally cut them open and unfold them carefully.

Another owner op with a 14t exc had the service dept out as he felt the machine was down on power and pumps seemed noisey. ( within warranty)
Engineer checked the machine over, pressures etc, tweeked the pumps and left.
Almost 2wks later the slew jammed solid while on a batter.
When the pipes were removed from the slew motor the ends were jammed solid with rubber as the pipes were laminating from the inside
IF the mechanic had taken notice of the ops fears about the pumps he could have pulled the tank filter and probably found unusual amounts of rubber :beatsme

The good thing was it was taken away and a lot of pipes replaced under warranty.

 

[Anto Modded]

Well we have a 2 45 gallon drums of hydraulic fluid, its just the filters. How does the rubber get inside ? is it the hose's or bad quality hoses. I will cut the filter up and post up pics. Machine isnt down on power anyway. Cant wait to check the bloody filter now.

 

[strott]

The Kubota KX41-2/3 requires hydraulic oil and filter changes at 1000 hours along with engine coolant changes and other things such as the usual oil and filters plus the reduction gear oil.

The return line filter should also be changed at every 500 hours especially if you run a breaker on the machine.

 

[Anto Modded]

Machine is piped but was never used. I ordered a hydraulic return filter and a suction filter. I take it the suction is in the tank and return is in the return line to the tank somewhere

 

[strott]

Yep the return line is on the tank which on the 41-3 is under the seat on the left whether it is the same on the 41-2 is up to you to find out!!!!

If you want a full breakdown of the service/maintenance requirements for the 41-3 to help guide you for your 41-2 then just let me know.

 

[Anto Modded]

Yes that would be great

 

[Anto Modded]

Can only find one hydraulic filter, in the tank. I thought there was 2. I stripped the seat out and rear aswell in search of a second filter and cant find one. I ordered the filter and will have it tomorrow along with a air filter and other bits. Crowd i ordered from said there is only one hydraulic filter on the machine and its in the tank. I will take pics of the filter tomorrow when i take it out and cut it open

 

[strott]

You may just have a return filter then (not sure if this is also the case on the 41-3!!)

These return filters are pretty expensive so the less of them the better!!

 

[Anto Modded]

Actually there is 2 filters, one is in the bottom of the tank and the other is mid way, i was looking outside for the 2nd one. Showed someone the diagram and they pointed out that its in the bottom of the tank. Also found a filter kit for 49 euro, will ring tomorrow and see if it covers the air filter, dsl filter and 2 hydraulic filters. If it does ill do the lot on it and that will be it done for a while

 

[strott]

Sounds like a good price there - I know the return filter alone is about £70.00 from my dealer.

 

[Anto Modded]

I dont think these are genuine filters, baldwin filters i think.