L48 Hydraulic Failure

[Desertdigger]

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.

 

[subiccs]

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.

 

[Desertdigger]

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.

 

[Eric McCarthy]

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.

 

[Desertdigger]

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.

 

[Desertdigger]

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.

 

[Eric McCarthy]

Vic had mentioned 4 filters total, did you replace all 4 of them?

 

[Desertdigger]

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.

 

[Eric McCarthy]

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

 

[bosshogg]

That suction screen is where I would concentrate on....

Someone previously stated the pump had "no excessive wear". I would imagine there is very little tolerance between gears on a hydraulic pump and what might look fine may be entirely out of spec...just a thought. Again, that inlet screen suggestion is where I would guess the prblem lies.

 

[Apogee]

Is there more than one pump on the L48?

Any chance there are two and you're looking at the wrong one?

Just a thought...

Steve

 

[Desertdigger]

Steve - There are three hydraulic pumps on the L48. I believe the main two in the front control the loader, 3-point hitch, and power steering. The third works the auxiliary port in the rear which for me would control the backhoe swing function. I was able to get the tractor moved over to the backhoe last night and hook up the hoses. The backhoe swing works but nothing else. This leads me to believe my problem lies somewhere in the pump 1 & 2 system.
Craig

 

[Desertdigger]

I think I may have found the answer to this problem. Since the problem seemed to be centered around the main hydraulic pump (1&2), I finally ordered a new one ($950). When I pulled the pump out I found the drive shaft coupler splines that mate to the pump shaft had sheared off. I couldn't see it until the pump was completely removed so I could pull the drive shaft coupling off of the pump. There was also damage to the pump shaft as well. I have ordered a new coupling from Kubota. I hope to have it and replace it in about a week.

 

[tewilliams]

I am having that problem now. Last week the flex plates broke on one end of

the pump driveshaft. I replaced all 6 ($102). Ran it for about 45 mins.

Now tractor will drive but steering, loader and backhoe do not work.

I checked plates, they are good. I added oil and changed filters.

Some say it was the input flange on the front pump. What did you find?

Jan 30,2013 tewilliams1957@bellsouth.net

 

[tewilliams]

My L48 is doing the same thing. No hydraulics on 1 and 2 pump ( backhoe, loader, steering) I added oil, changed the filters, checked drive shaft and flex plates, pump flange ok, let it run for 25 minutes, still NO hydraulics. what is it ??? HST and swing from pump 3 works ok.

 

[tewilliams]

My L48 had hyd problems with pump 1 and 2.
They are mounted on the front under the radiator.

It was the coupling that splines onto the pump.
All the splines had worn off the coupling
( PN 32751 10910 $62.00 )