Loader hydraulic problem

nybirdman · Jan 22, 2011

I had made a post earlier on a problem that I had(have) with the loader on my Kubota tractor.It is an L4240 with 854 loader.The problem started this winter when I put the FEL mounted snow-plow on,it is a 8ft.Curtis.The dealer had plumbed the third function two years ago.I have used the plow for two years,and have a thumb that works.
When this problem occurs I have no loader functions.....then it will start working again.
The dealer had the tractor for four days and can't find a problem.The owner seems to think is "hydraulic lock".I don't think there is any cross-over or relief on the plow.If this is a "lock problem" how do I cure it?There are two cylinders for angling the plow.

kennyd · Jan 22, 2011

When it stops working, does the engine labor at all? When the FEL stops working, does the 3PH also stop working?

All the Curtis plows I have seen come with a CRV (crossover relief valve), there should be a small aluminum block mounted to the plow frame with 4 hoses going to it. With or without it, I don't think that would be your problem.

I am leaning towards a problem in the solenoid valve-like it's getting stuck half way and blocking the ports.

nybirdman · Jan 23, 2011

kennyd
thanks for the response...I remember that aluminum block on the plow when I bought it(used truck plow) when the dealer plumbed the plow they didn't reuse this part.
In my other life,I was a pipefitter,did a little hydraulics..but not familiar with tractor hydraulics.I had told the mechanic on the phone that I thought a spool was sticking,or some electrical problem.
Dealer has been great..tough problem to find...they are returning the tractor next week,all I can do see if the problem recurs.
I didn't send the plow with the tractor,had to do some repairs to it,if I have to send the tractor back I will send the plow with it.

Ford tractor · Jan 23, 2011

It sounds like there may be ice forming in the hydraulic fluid, maybe inside the 3rd function valve.

nybirdman · Jan 23, 2011

Tractor was just seviced by the dealer,changed all fluids....replaced the third function valve switch,this is why I had thought they had created the problem.I have used for two years prior with no problems.

kennyd · Jan 23, 2011

Again I will ask:

When it stops working, does the engine labor at all? When the FEL stops working, does the 3PH also stop working?

Two years ago I went to use my grapple, and the diverter would not work...I finally had to take the valve apart and I found that the spool had corrosion on it! Not much-but enough to keep the spool from sliding in the bore (see pictures below) This was before I had my pole barn and I kept the loader outside under a tarp. I guess there was just enough moisture in the fluid to do this.

My point of the story is to let you know that it only takes a very little something to stop the spool, and if its getting stuck then I think that may be the problem. Most spools have a hole so you can manually operate the valve, Nelson describes in post #8 of this thread.

Is yours a WR Long valve or Kubota?

nybirdman · Jan 23, 2011

The engine does not labor when trying the FEL,didn't try the three point.
Like I said I was a maintenance pipefitter I know about dirt etc. in the spool,but like I said the dealer did the service,fluid,filters etc.

nybirdman · Jan 23, 2011

Forgot,I assume they used a Kubota third function valve,don't know for sure until I get the tractor back.

wdchyd · Jan 23, 2011

Hydraulic Lock sometimes can be explained by a restriction in the return line.....whereas pressure builds up and cannot return properly to tank unrestricted......

That said be sure to check easy stuff....ie: quick-connect not completely snapped shut (blocking flow), 3ph lever in "Raise" position, a spool on a control valve partially shifted (not centered)....

when this condition happens, is there pressure in the main outlet line from the pump when all/any functions in neutral position..??..or pressure build up in return line to tank.....