Hydraulics fail when tractor warms up?

[autocol]

Hi Guys,

I'm new to this site, and new to fixing tractors. I'd usually search the forums for an existing answer more vigorously than I have, but I don't really know what anything on the tractor is called, so I don't know what to search for!

Anyway, hopefully you fine fella's can help me out.

I have a little old Kubota tractor, with a front end loader. When you first start the tractor the bucket will raise and lower correctly, but it's a bit slower than it should be, and sort of "jumpy". If you let the tractor warm up, the hydraulics get to the point where they barely work, if at all.

Now, if I understand correctly the hydraulic oil is shared with the gearbox? (I think I remember my dad, the original owner of this little tractor, saying that... but he's been dead for 12 years so the memories are hazy!). Does this mean the oil is getting too thin and therefore not working properly? Would changing all the oil potentially fix the problem? Or does it mean a valve is leaking somewhere maybe?

I don't really know where to start looking, or what to look for. I'm a decent home mechanic, but I have no experience or knowledge about hydraulics.

Oh, and the oil is the same stuff that was in there when my dad died, so it's at least 12 years old - and knowing my dad he may not have changed it for 10 years prior to that either!! :laughing: If changing the oil is the first port of call, what do I ask for?

Any help or advice you could offer would be great.

 

[J_J]

Go ahead and change out the fluid, and install a hyd gage in the system, and check the pressure. Read your manual, or call the dealer and find out what the pressure should be.

Move the the 3pt lever about midway, and see if there is any difference.

 

[Mechanos]

Do as JJ suggesested... but in addition to just changing the oil, make sure you remove and clean the strainer and also install a new hydraulic oil filter.

 

[mmurphy]

If you post model of Kubota you have, some one may even be able to help more with other info about tractor.

 

[brain55]

Also post what model it is. "Little old Kubota" doesn't narrow it down much. The loader model would help too. It will help us point you in the right direction if you are unsure of where the suction screen or filters are. Change the hydraulic oil and clean the suction screen it needs to be done anyway. My bet is that you won't notice much of a change, it could help with the hydraulics feeling jumpy though. The next step would be to have a flow test done on the hydraulic pump. A pressure test by itself will not tell the whole story, you will need to know how the pump flow is affected by the pressure, you can have pressure and no flow. From the description you gave, I would just about bet that your hydraulic pump is worn out. That is why I do a flow test first, to confirm or eliminate that possibility. You can waste a lot of time checking other things and it still be the hydraulic pump.

Brian

 

[Egon]

Is the tractor HST or is it gear/clutch unit?

Can you tell where the hydraulic pump is mounted?

Is the pump internal or external?

Does it have reservoir tank?

 

[wdchyd]

Also post what model it is. "Little old Kubota" doesn't narrow it down much. The loader model would help too. It will help us point you in the right direction if you are unsure of where the suction screen or filters are. Change the hydraulic oil and clean the suction screen it needs to be done anyway. My bet is that you won't notice much of a change, it could help with the hydraulics feeling jumpy though. The next step would be to have a flow test done on the hydraulic pump. A pressure test by itself will not tell the whole story, you will need to know how the pump flow is affected by the pressure, you can have pressure and no flow. From the description you gave, I would just about bet that your hydraulic pump is worn out. That is why I do a flow test first, to confirm or eliminate that possibility. You can waste a lot of time checking other things and it still be the hydraulic pump.

Brian

.......:thumbsup:.......My thoughts exactly

 

[autocol]

Hi Guys, thanks for all the help!

Okay, I'll do my best to answer the questions you've got:

First, the tractor is a Kubota B6100.

The loader doesn't have a model number that I can find, just a Kubota stamp. If it makes any difference, it also has a grader blade on the back that powers upwards hydraulically (down is just gravity powered I think), and it demonstrates the same issues (slow and jumpy when cold, almost completely inactive once warm).

Is the tractor HST or is it gear/clutch unit?
Well, I don't actually know what HST means, but it certainly has a mechanical gearbox if that's what you mean.

Can you tell where the hydraulic pump is mounted?
I'm pretty sure it's on the right hand side of the engine, under the exhaust manifold and behind the fuel pump.

Is the pump internal or external?
External, I think. I wouldn't take that as gospel though because I'm only fairly sure that what I'm lookin at is the pump! It's about the size of a petrol V8 starter motor. It's got a decent size "hard line" down to the bottom of the gearbox which I assume is the pickup.

Does it have reservoir tank?
I can't see a reservoir, though the whole pump is fairly obscured by the exhaust and the shroud around the engine.

This ad listing features a tractor that looks pretty much identical to mine, and the specs it lists (engine size and horsepower) all match what's written on the plate on mine. It's also the only image I could find on the web which shows a loader that looks like mine. All the others I found look slightly different.

Again, thanks very much fellas. I really appreciate your help.

Col.

 

[Egon]

As per J_J and mechano. Also check the oil level before draining.:thumbsup:

 

[jinman]

Col. it appears to me that you know so little about this tractor that you would be far better off to take it to a Kubota dealer's shop and have them look at it. While there, also see about ordering an Operator's Manual and read it thoroughly. When it comes to tractors, you just can't beat a good knowledge of how things work and what the maintenance points are. Rather than take a chance of making the situation worse, why don't you get it looked at by experts and spend your time and money well on becoming more familiar with your tractor? I have an idea you are going to say that the shop will be expensive, but in my experience, nothing is more expensive than doing the wrong thing. Give yourself some time to learn and next time you may be able to take care of the problem yourself.:thumbsup: