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Old 08-20-2012, 10:45 AM   #1
Desertdigger
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Default L48 Hydraulic Failure

I have an L48 TLB with a little over 1200hrs on it. It has been working fine but the front loader, 3-point hitch, and power steering all quit working. I did notice the front loader seemed to require more rpms to provide the same amount of lift it had been providing about 50hrs or so ago. The fluid is clear and topped off (I check it regularly). I can see the drive shaft to the front hydraulic pumps spinning when I start the engine. Any ideas where to look for the problem? I am new to hydraulic systems and Kubota mechanics.

Last edited by Desertdigger; 08-20-2012 at 11:32 AM. Reason: Additional information
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Old 08-20-2012, 07:22 PM   #2
subiccs
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Default Re: L48 Hydraulic Failure

I am having the same problem with my B6100. I pulled the pump off no excessive wear changed seals put it back on and no go. Should have checked the shaft where it ties in to the motor before I put it back on. Didnt get any helpfull hints from anyone yet either. Hope some one can help us with our problems. Good luck if you find an answer please let me know.
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Old 08-20-2012, 07:56 PM   #3
Desertdigger
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Default Re: L48 Hydraulic Failure

My Kubota dealer really thought the problem was the diverter valve at the rear of the tractor that switches between having the backhoe or the 3-point hitch in operation. I have two such valves - that one which goes in and out, and a second that moves from left to right. I have moved those numerous times with no change. My Kubota shop manual also mentions the Main Relief valve as being a possible problem. If I have time tomorrow I may tear into it to see if it has a broken spring or something. I will post if I get to it and any results I have. Good luck to you to. This is very frustrating to not have a more obvious cause.
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Old 08-20-2012, 08:35 PM   #4
Eric McCarthy

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Default Re: L48 Hydraulic Failure

Dont give up hope yet, maybe somebody will come around with some helpful info. Most of us on here are owners helping other owners who have learned from trail and error. So maybe no one else has had a problem such as the ones you both are having. Maybe Service Dept Vic will chime in with info since he's a Kubota tech and a moderator of the forum.
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Old 08-20-2012, 09:01 PM   #5
Service Dept Vic
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Talking Re: L48 Hydraulic Failure

Hydraulic filters!!!!!!!!!!!!!!!!!!!!!!!!!

On the B6100 I guarantee you the screen is completley plugged with crap, and while the L48 has 1200 hours and the hydraulic fluid appears 'clear' I didn't read that the hydraulic filters have been cleanerd, serviced or replaced.

The gradual loss of hydraiulic performance coupled with an increase in engine operating rpms in order to compensate for 'slow' hydraulics is the tip off that the filters are plugged and the gpm throughput is reduced and restricted.

The L48 has a pair of high flow hydraulic filters mounted in tandem, a spin on cartridge style filter for the HST and a seperate internal mesh screen style filter on the suction line where it enters the case of the transmission.

That's four filters and four real good areas to look at because that's where the fix to this problem will be found!
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Old 08-21-2012, 05:22 PM   #6
Desertdigger
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Default Re: L48 Hydraulic Failure

Thanks Vic for your input. I went to my local Kubota dealer today and picked up new filters. I hope to get back to this project tomorrow (Wednesday) and will provide feedback when done. I was hoping to do it tonight but it looks like we have a wicked storm moving in for the evening. It is monsoon season here in Tucson.
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Old 08-22-2012, 07:43 PM   #7
Desertdigger
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Default Re: L48 Hydraulic Failure

I replaced all three filters and thoroughly cleaned the transmission oil strainer at the bottom of the transmission. Still have no hydraulics. Anybody have any ideas what to try next? Thanks.
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Old 08-22-2012, 08:12 PM   #8
Eric McCarthy

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Default Re: L48 Hydraulic Failure

Vic had mentioned 4 filters total, did you replace all 4 of them?
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Old 08-23-2012, 08:32 AM   #9
Desertdigger
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Default Re: L48 Hydraulic Failure

Eric - There are three replaceable filters (regular type oil filters) and one screen on the suction line you clean and put back. Two of the replaceable filters are considered hydraulic filters and are larger than the one transmission filter. The three filters were $120 at my Kubota dealer. I will scour my shop manual today and decide where to look next.
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Old 08-23-2012, 11:20 AM   #10
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Default Re: L48 Hydraulic Failure

Yeah I had thought about it a little while after I posted that at 11pm lastnight!
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