M4900 no power steering and slow hydraulics... help please...

[motocrossguy]

Hello everyone, new to your site but lost and need help.

I have a M4900 (well actually not mine, my neighbors) and I am unsure of the year. Unfortunately I have found myself trying to work through a Hydraulic problem that I just cant get figured out.

It started when the rams on the FEL began to leak and we took the loader off the have the rams rebuilt... I thought you would have to bypass the lines to allow the fluid to continue to circulate but there are no lines left after the FEL has been disconnected. He used the tractor quite a bit and shortly after that the seal in the hydraulic pump pushed out and forced hydraulic fluid into the engine oil. The neighbor got a rebuild kit and rebuilt the pump and all worked well for awhile.

recently it began to show signs of the power steering fading after about 45 minutes of running and the FEL cant handle any kind of load. loader goes up and down and bucket moves but if you try to raise it with any kind of load it will not lift, and now there is no power steering at all. if you flip the PTO the shaft spins but I dont know if it can handle running the bush hog, as it is also a repair that I inherited and I'm half way through...

What research I have done has pointed to the 2 valves by the transmission... which I have removed and check for blockage... didn't see anything that would warn for concern. HOWEVER... now that I put them back in, and after it was running it was pushing hydraulic fluid out the dipstick tube. He had it way overfull to start with, but it wasn't overflowing. Still have FEL controls but weak, PTO still spins, and still no power steering...

Tractor has 950+ hours on it and when it started to act up this last time he did a complete hydraulic fluid and filter change. No change in condition. Though maybe air in the system... found tonight where it looks like the line from the FEL to the 90 degree fitting under the seat was smashed when the FEL was removed but everything worked when we put it back together.... I don't know... I have inherited this mess and when I tried to contact the local Kubota dealer they were extremely rude... and that's being polite on my part.

Frustrated and not sure where to turn next so if anyone has any ideas, I could sure use some help.... Thanks in advance!

 

[Eric McCarthy]

See if you can bleed the air out of the system, could be the problem.

 

[North Idaho Wolfman]

That tractor has a 2 stage pump one stage runs the steering and the PTO, the other stage runs the three point and the accessory hydraulics.
It sounding like if the problems all started after the fluid and filter change that in there lies the problems.
What fluid was used and did he change both filters, and with what brand?
When the pump seal went out was just the one seal get replaced or was there more done to it?
Being that your having problems with both the steering and hydraulics that leads me to believe that the problem is in either fluid type, wrong filters or still bad pump.

One situation that can happen on these models of tractors is that the three point controls can get out of adjustment and make the tractor go into bypass and because of that it will cause everything to go crazy, try moving the three point control to a mid point and see it that changes anything.

You really need to load a couple of pictures of the bad parts to determine if that's adding to the problem.

 

[Bulldog]

First thing I would do is check the hyd pressure.

 

[Tx Jim]

Ditto on checking hyd pressure.

 

[motocrossguy]

That tractor has a 2 stage pump one stage runs the steering and the PTO, the other stage runs the three point and the accessory hydraulics.
It sounding like if the problems all started after the fluid and filter change that in there lies the problems.
What fluid was used and did he change both filters, and with what brand?
When the pump seal went out was just the one seal get replaced or was there more done to it?
Being that your having problems with both the steering and hydraulics that leads me to believe that the problem is in either fluid type, wrong filters or still bad pump.

One situation that can happen on these models of tractors is that the three point controls can get out of adjustment and make the tractor go into bypass and because of that it will cause everything to go crazy, try moving the three point control to a mid point and see it that changes anything.

You really need to load a couple of pictures of the bad parts to determine if that's adding to the problem.

I would be happy to photo anything that might help and I greatly appreciate you taking the time to respond. I'm working on it today so I will photo and try the middle setting on the 3 point.

As far as the filters and fluid goes he said he went back to the Kubota fluid and filters, but I can make sure today because I am sure I will see him today.

I understand the back section of the pump if for the power steering and the front is primarily for the components (from what I understand) I was told by him, that he rebuild the whole pump... I didn't question it until we got about 16 hours on it and the steering got weak one day and I immediately stopped and found the hydraulic fluid in the oil a second time... I pulled the pump that time and found the snap ring had come out of the grove and pushed the seal out... not sure why... maybe he didn't have it seated properly but I replaced the seal and oil change and on we went.... many hours later we are back at a poor hydraulic issue again... so the time we put on the machine leads me to believe his "pump rebuild" went ok... what gets me is that everything worked for awhile then progressively got worse.

I seem to get the problems after they have already escalated to this point so what went on prior to the complete loss of the system may have a few details missing. Again I greatly appreciate the help.

 

[motocrossguy]

First thing I would do is check the hyd pressure.

unfortunately I don't have a gauge that will go that high... where would be the best place to test it? thank you for the help!

 

[motocrossguy]

See if you can bleed the air out of the system, could be the problem.

I did try that... in my own redneck way... I crack the line at the pump and also at the front axle... no help of any kind. so before I made matters worse I stopped. I don't have the service manual so I don't know exactly what the procedure is....

 

[Bulldog]

unfortunately I don't have a gauge that will go that high... where would be the best place to test it? thank you for the help!

Northern Tool list a 5000 psi guage for $20. If you have rear remotes you can plumb it with a male coupler and plug it in your remote. Engage the remote and it will show you the pump pressure.
Obviously it can be done different ways but this way is pretty easy and it will save from having to tap into the hyd system.

 

[Tx Jim]

If there are no rear remotes then couple gauge into FEL control valve to test psi.

 

[motocrossguy]

ok... so today I finished the bush hog and attached it... the tractor had no issues turning the PTO even at a lower RPM... about 1000. So I tried to make a pass and at 1200 RPM the power steering seemed to work fine. At 1800 RPM everything worked fine... when I back it off to 800 RPM no power steering. I made 2 passes with the mower and checked the fluid... it looked airated. It did start to fade even at 1800 but after working it back and forth once... it started to work again... air in the system? If so how would I go about bleeding it?

 

[North Idaho Wolfman]

Getting air in it like that spells out like a cracked intake line or some other location where it's sucking in air.
I would start at the pump pulling the intake lines and checking every connection and line.

 

[Tx Jim]

I think I'd try replacing the o-rings on the suction pipe. Parts schematic shows a total of 5 o-rings on this pipe.

 

[Bulldog]

Check the rubber hose on the suction line. They can be cracked and sucking air without leaking a drop of fluid.

 

[motocrossguy]

Check the rubber hose on the suction line. They can be cracked and sucking air without leaking a drop of fluid.

The suction line is the large line that comes in to the bottom of the pump correct?

 

[motocrossguy]

I think I'd try replacing the o-rings on the suction pipe. Parts schematic shows a total of 5 o-rings on this pipe.

any chance you could add that schematic?

thank you

 

[motocrossguy]

Getting air in it like that spells out like a cracked intake line or some other location where it's sucking in air.
I would start at the pump pulling the intake lines and checking every connection and line.

Thanks again! I forgot those dang pics! I didn't get a chance to talk to the neighbor either... oh well... I gotta get it done so Ill stay at it...

When you refer to lines and connections are you talking suction only right... or all?

 

[North Idaho Wolfman]

Here you are, just focus on the suction side right now.

 

[SteveF]

Hopefully the fluid didn't become contaminated with some chemical that affects rubber seals, lines, etc. I once accidentally many, many years ago put power steering fluid in my break reservoir. Well things were okay for a while but then the breaks got spongy. I opened the break reservoir and the rubber air displacer sprung out like a jack in the box, all wheel cylinder seals were ruined. Had to flush and flush and replace everything made of rubber. You hyd fluid may or may not be contaminated. Not sure I've read anything above that would rule it out though.