Backhoe L35 lost all hydraulics

   / L35 lost all hydraulics #1  

fastback88

Bronze Member
Joined
Mar 9, 2011
Messages
58
Location
Sturgeon Bay WI
Tractor
Kubota L4200gtsc,LA680 loader
On my friends 98 l35 with 1600hrs lost hydraulics to the backhoe, loader and 3 point,while using the backhoe at an idle for about 10 min he went to dump a bucket of dirt and after dumping lost the hydraulics (the power steering works and drives fine )and can't raise the loader, hoe or 3pt. The hydraulics never got weak or noisie.I Just sold this tractor to him and he has only used it a couple of hrs since he bought it from me and this happend :( I owned the tractor since 650 hrs and have done all the matinence as the manual says and never had a problum. Any help would be great!
 
   / L35 lost all hydraulics #2  
Shut the tractor down and disconnect and reconnect all of the hydraulic quick connect hoses. Give it a try then. Sometimes they pop about half way loose and stop the flow of fluid. Do not go by looks because you can't tell by looking. I would try the hoses going to the back hoe control valve first. The ones that you have to connect together when you remove the hoe. :thumbsup: Report back and let us know.
 
   / L35 lost all hydraulics #3  
I was told to never use the machine at idling power for any length of time. It Blues the hydropump or something. It cannot cool the fluid quick enough as well. At least thats what I was told.
 
   / L35 lost all hydraulics #4  
It sounds like you lost your front hydraulic pump. The L-35 has two, one for the power steering and GST valve assembly, and one that runs the loader, hoe, and 3-point hitch.

The pump is a standard meshing gear pump. It is a positive displacement pump. Downstream of the pump is a relief valve. The speed of the motor, and hence the pump, simply determins the hydraulic flow through the pump.

When you don't need hydraulic flow, the pump just pops the relief valve. It won't hurt the pump to run at a lower speed, but the hoe won't perform very well. I've seen other people recommend about 1900 RPM when using the hoe, due to the very sensitive swing.

Alternatively, if the front diverter valve is open you would also lose pressure, but that wouldn't happen accidentally.
 
   / L35 lost all hydraulics
  • Thread Starter
#6  
Checked the hoses and the releif valve and that's not the problum.It must be the pump.He was only using it at an idle to get used to it, as it was his first time using a hoe. Thanks,
 
   / L35 lost all hydraulics #7  
Hey Guys, I just lost all accessory (FEL/BH/3pt lift)power on my L35. I heard a slight chatter a few times during use in the last few weeks but it went away before I could pin-point where it came from. Where do I start looking? I was operating the FEL when it happened. Don't think it is the hose disconnect for the BH. Where is the relief valve located? I'm at the point that I can remove the pump but wanted to know if there was some troubleshooting before I disconnected it. Thanks Charlie
 
   / L35 lost all hydraulics #8  
I'm back. I have loosened the three supply and return hoses on the FEL control valve and started the tractor with no leaks at all.....???? Can I assume that the pump is not putting out at all and when I remove it it will display its failure or is there a relief valve that can divert all flow to the FEL controls? Inquiring minds want to know. Thanks Charlie
 
   / L35 lost all hydraulics #9  
Time to test hydraulic pressures. Need to get a gage setup and install between the pump and one of the cylinders.

I had similar hydraulic loss last year and after thinking the pump, dealer installed a gage and found main relief stuck open.
 
   / L35 lost all hydraulics #10  
When was the last time you changed your filter?
Clogged filter would be my first guess.
 

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