Hydraulic Failure After New Clutch Installed

   / Hydraulic Failure After New Clutch Installed #1  

MichKubota

Silver Member
Joined
Nov 22, 2010
Messages
126
Location
Holly, MI
Tractor
Kubota L2850 Hydrostatic/ Deere 5410 w/loader
Can anyone help?

I have a Kubota L3650GST tractor and after installing a new clutch and pressure plate the hydraulic pump for the steering and transmission isn't pumping.

The tractor had to be split and most of the hydraulic lines opened and FEL removed for this job.

The hydraulic pump (located just forward of break pedals) has two separate pumps within one assembly. The one on the front of the assembly is for the rear 3pt hitch and loader. The one on the rear of the assembly is for the power steering and GST transmission. Both pumps get hydraulic oil from the transmission sump.

After starting tractor (first time after clutch install) I found the following symptoms:

1. Started tractor and found no leaks or unwanted noises (thats good).

2. Put shuttle shifter into forward with clutch down, let out clutch and tractor pulled forward. Put shuttle shifter in reverse and let out clutch and tractor went rearward (that's good too). Only moved tractor 10 feet forward and back about 3 feet.

3. Put shuttle shifter back into forward with clutch down, let out clutch and tractor pulled forward. I began turning steering to avoid vehicle and discovered no steering at all. This is a fully hydraulic steering system. No drag lines or other hard connections to front wheels.

4. Tried Pt hitch hydraulics and they work correctly. Used them multiple times.

5. Spun steering wheel slowly cw and ccw, thinking I had to bleed hydraulics in steering. This didn't help.

6. Stopped tractor to check service manual for ideas.

Removed hydraulic delivery line from hydraulic pump to steering and started tractor. No oil being pumped out with engine running.

I thought that is impossible. How could there be no oil or pressure for the power steering but pressure for the GST transmission. It is the same pump just different delivery pipes.

So I tried the transmission again and found it wasn't working either. OK, not sure why it worked for a few feet but it's not working now and that makes sense that it shouldn't if the pump isn't working.

Removed the pressure line on top of the pump and checked again. Still no coming out with engine running. However; I could see the gears within the pump moving just no oil being pumped.

This has really got me stumped. The pump for the 3pt hitch is working and the oil for that pump and the steering pump come from the same place. It's all one assembly.

I would think if the pump for the steering failed (the gears move with tractor running) some amount of hydraulic fluid would get pumped out.

Sorry for the long story but as usual the devils in the details.

The photo is just example of pump like the one I have on L3650.

Any ideas what I should try next?

Thanks
 

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   / Hydraulic Failure After New Clutch Installed #2  
The hydraulic pump (located just forward of break pedals) has two separate pumps within one assembly. The one on the front of the assembly is for the rear 3pt hitch and loader. The one on the rear of the assembly is for the power steering and GST transmission. Both pumps get hydraulic oil from the transmission sump.

And are you sure the one pump is for both the tranny and the power steering?
 
   / Hydraulic Failure After New Clutch Installed
  • Thread Starter
#3  
Yes, the rear hydraulic pump is for power steering and the GST transmission. I know that doesn't seem to make sense.

Within the GST transmission the hydraulic oil/pressure is used for two purposes:
1. Control the hydraulic clutch.
2. Move gear forks when changing gears.

Bob
 
   / Hydraulic Failure After New Clutch Installed
  • Thread Starter
#4  
Couldn't work on tractor for a few days over Thanksgiving.

I added 2 more quarts of hydraulic fluid this morning. This took the level in hydraulic level sight glass (on side of transmission) from dead middle of glass to a little over full mark.

Let sit for another 2 hours and started tractor. After about 60 seconds of running, the power steering and transmission began to working.

So, bottom line is I think the power steering/transmission hydraulic pump was not getting primed. Anyway, just glad it is all running correctly now.

When I started this project the FEL was removed. Not sure if this would have taken away some of the fluid.

Bob
 
   / Hydraulic Failure After New Clutch Installed #5  
Mich
Glad to hear you are back in business. Nice to get it fixed without a big expense.
 
   / Hydraulic Failure After New Clutch Installed #6  
I love fixes like that. I would be so relieved.
 
 
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