John Deere 300 b backhoe select hydraulic problem

[Suzukibruce]

When I fixed the leaking diesel fuel tank I removed and drained the hydraulic tank. Filled the tank back up and filled the transmission to the proper fluid level. Loader doesn稚 work. The stabilizers work fine, some of the backhoe functions but not all cylinders are working. The tractor runs in gear and the power steering works. Is there a filter in the pump that may be clogged?

 

[Erik M]

I am guess you have air in some of the lines and need to bleed the lines to get rid of the air bubbles.

If you had drained the hydraulics it would have been a good time to change the filter.

 

[Tx Jim]

Operating hyd functions will bleed any air out of system. Yes there's a small filter in frt hyd pump but I doubt that filter in pump is at fault. Did you install new hyd filters under tractor & check/clean sump screen? I also suggest to check hyd stand-by pressure which should be 2250-2350 psi.

 

[Suzukibruce]

Operating hyd functions will bleed any air out of system. Yes there's a small filter in frt hyd pump but I doubt that filter in pump is at fault. Did you install new hyd filters under tractor & check/clean sump screen? I also suggest to check hyd stand-by pressure which should be 2250-2350 psi.

I worked the stabilizers and boon for over 1 hour with no improvement. I also changed the filters with tractor hours 3 before this occurred. The only filter I didn稚 look at was in the pump. Any idea where it is located? I believe there has been no work done to this machine in 10 years.
Thanks

 

[Tx Jim]

As I previously stated it will shock me if filter(key 17) is the problem. Just for your info I served as a JD dealer service manager from '75-'87. Closed-center hyd's such as your tractor has requires very good diagnostics when a hyd problem arises.

 

[Suzukibruce]

As I previously stated it will shock me if filter(key 17) is the problem. Just for your info I served as a JD dealer service manager from '75-'87. Closed-center hyd's such as your tractor has requires very good diagnostics when a hyd problem arises.

Started the tractor today and the backhoe responded as normal. Loader is still out. I have no way of getting the machine to JD at this point so I'm on my own. What tool would I need to check the pump pressure please.

 

[oldnslo]

If the backhoe is working properly I would suspect that the pump is not getting a pilot signal from the loader valve to go on stroke. Not sure or how to test for this pilot signal though

 

[Tx Jim]

One can check hyd stand-by pressure by installing a 3000 psi gauge on hyd pump port(kry 24)

 

[Tx Jim]

If the backhoe is working properly I would suspect that the pump is not getting a pilot signal from the loader valve to go on stroke. Not sure or how to test for this pilot signal though

Are you thinking about a CCLS hyd system? JD 300B doesn't utilize a pilot signal to put pump in stroke merely a drop in hyd pressure which allows pump pistons to be pushed back by springs against the already rotating pump shaft allowing pump to pump oil.

 

[medic0648]

Are the heavier movements not working? If so check the filter in the pump. It is in line with the pressure control internal to the pump. Check inside the transmission toward the front for spraying and bubbles. Pull the return line on the rear and start the tractor. Make sure with all the controls in neutral there isn't any flow.