300 U hydraulic DEAD ?

[300 dave]

Greetings all - My 300 U hydraulic system does not seem to be working at all. I raise the handle to lift, and generally nothing happens. Once in a while it will lift the draw bar. I looked in the tank under the seat and see no movement of fluid at all (peeking in through fill hole). Over the past 20 years I've had this machine, it will occasionally screech and bog down for a second. Otherwise it runs well. I have rebored one orafice in the valve as per instruction here. I am thinking the pump is shot. Any thoughts appreciated. I think I can borrow one off another machine, Can this be rebuilt?
thanks all -will check back later
dave

 

[NY 986]

Greetings all - My 300 U hydraulic system does not seem to be working at all. I raise the handle to lift, and generally nothing happens. Once in a while it will lift the draw bar. I looked in the tank under the seat and see no movement of fluid at all (peeking in through fill hole). Over the past 20 years I've had this machine, it will occasionally screech and bog down for a second. Otherwise it runs well. I have rebored one orafice in the valve as per instruction here. I am thinking the pump is shot. Any thoughts appreciated. I think I can borrow one off another machine, Can this be rebuilt?
thanks all -will check back later
dave

If everything else appears normal then you might as well remove and inspect the pump. Might find a simple problem like a sheared key on the pump shaft. But those pumps did not have an indefinite lifetime so yours may have run its course and died. Good used pumps are very difficult to find so be prepared to spend several hundred dollars on a new replacement. Those systems are what I would call noisy so the absence of any noise including a "hum" when moving a control lever indicates something is up with the pump. BTW since your distributor works off of the pump shaft observe all markings relative to the distributor so as to maintain engine timing.

 

[BarnyardEngineering]

If everything else appears normal then you might as well remove and inspect the pump. Might find a simple problem like a sheared key on the pump shaft. But those pumps did not have an indefinite lifetime so yours may have run its course and died. Good used pumps are very difficult to find so be prepared to spend several hundred dollars on a new replacement. Those systems are what I would call noisy so the absence of any noise including a "hum" when moving a control lever indicates something is up with the pump. BTW since your distributor works off of the pump shaft observe all markings relative to the distributor so as to maintain engine timing.

Litmus test on the "sheared key on the pump shaft" is, does the tractor run? The distributor is driven off the hydraulic pump, and if you shear the key, the distributor stops turning.

 

[300 dave]

tractor runs like a top Starts up quickly, runs dependable -maybe a tad slow on the governor maintaining rpm-but nothing to complain about.
BUT, every once in awhile there is a screeching sound and the engine bogs down and it is gone. It has done this for about 15 years I've had this machine. I have asked about it here and drilled out an orifice in the valve box,changed the fluid, flushed out the system as I could -still have the problem.
I see no movement of fluid in tank under seat. Tank is more than full, well above the "full line"
Draw will lift sometimes but slowly and NOT every time when I want it to.
I am baffled.

 

[RBoots]

There is a suction screen under that top reservoir/ cover that is quite fine and are prone to plug up.
Ross

 

[NY 986]

Litmus test on the "sheared key on the pump shaft" is, does the tractor run? The distributor is driven off the hydraulic pump, and if you shear the key, the distributor stops turning.

I was referring to the pump gear itself in turn mounted to the shaft. Some were keyed and some were not. I don't remember with the 300. Got nothing to lose in checking and in the course of removing the OP can check for possible blockage at the inlet. Should be able to push down on the tooth of the pump gear and see if the main shaft turns without disassembling the pump.

 

[300 dave]

oh yeah I had forgotten about that !!! what a ROYAL P.I.T.A. to pull that and check it. My fluid is not milky just like creamed coffee. There should be no crap in the system ( from where?), I have pulled it and cleaned it twice. Can that screen be back flushed with air pressure?