[Lawnjockey]

My loader won't raise unless I turn the steering wheel all the way to one side or the other. his is on a Jinma 284. About a year ago I had to rebuild one of the cylinders. I heard it was probably the "diverter valve" which give priority to the steering so I replaced that. No change in the condition. I am thinking some foreign matter may be in the actual control valve. Any advice on this is appreciated.

 

[TUDOR]

A similar problem happens with the MF GC series back hoe. On those tractors, it's the position of the 3PH control valve position. It must be centered for the hoe to operate correctly.

Your problem sounds similar, but is not identical. Check all control valve positions.

Another possibility is the plumbing is installed incorrectly for the power steering. It sounds as though the "return to tank from pressure relief valve" port on the P/S valve has been switched with the "power beyond port" hose which goes to the loader valve. This is actually the more likely possibility if the hoses were disconnected prior to the problem showing up.

It's a plumbing or control valve position problem somewhere. I don't think debris is the cause.

 

[Lawnjockey]

The saga continues. I don't think it is a plumbing problem as the cylinder plumbing only goes one way. As stated I replaced the priority valve and the tractor hydraulic pump. The loader will lift but slowly unless I raise the rpms. Even then it will only lift 1/3 of a bucket of dirt.

I am really wondering if a piece of %&$# from the crumbling cylinder seal could have gottn into the system and lodged in the port of the lift control valve causing a reduction in flow to the lift. Anyone ever experience symptoms like this or a crudded up lift valve?

 

[TUDOR]

The passages in a contol valve are quite large and it would take a large piece of debris to remain there to cause problems, and those will usually show up as restricted movement of the control handle.

Debris may get caught up in the hoses or lines to that cylinder and restrict oil flow. Disconnect the hoses to the cylinder and place the ends in a clean bucket. Start the engine at idle and cycle the valve both ways for a couple of seconds and observe the relative flows. If nothing obvious shows, do the same for another cylinder that is working at the correct speed and compare the flow rates. If you find a marked difference in flow rates, flush the appropriate line in both directions into the clean bucket and check for chunks.

If the flow rates match, go back to what was replaced since the last time the loader worked correctly and check the flows at that point. The various flows should all be the same, or very close, as what comes from the pump itself.

This should isolate where the restriction is and appropriate servicing can be done to that component. It may be that you got a bum diverter valve, but not likely. At the moment, the lines seem the most likely place for debris to be the cause.

 

[TUDOR]

The cylinder plumbing can only go one way, but if the power steering hoses were disconnected, they can easily be switched and be the source of your problem.

 

[Lawnjockey]

I wish that was the case. The problem developed before any hoses related to the power steering were disconnected.

 

[TUDOR]

Darn!!!

I guess it's the flow rate tests to isolate the problem then.