Loader Selective Control Valve

[Chrisfrank]

The SCV for my JD 750 loader has two handles - lift and bucket tilt. I think the SCV cylinder for the lift handle is leaking across its ports because the loader unexpectedly lifts all by itself without pulling the handle. JD wants over $650 for a new SCV (part number PC1873 70-30 or AM197083) and they don't sell any rebuild parts. Does anyone have any ideas on how to fix this? I've removed the SCV and it looks unserviceable. The exposed back end of the piston is round - there are no flats to get a wrench on.

 

[kennyd]

Welcome to TBN

Your setup looks like the picture below correct?

I think your best bet is to convert to a new joystick valve, get rid of the hard-lines, mount the new valve in a convenient location, then feed it with hoses.

You can probably do it for about $350, and you will have a modern style valve.

This would be a nice valve: https://www.surpluscenter.com/item.asp?catname=&qty=1&item=9-7401

 

[struell]

I know this is an old thread but I also have the same problem that just started with my JD750- the bucket lifts on it's own and you have to hold the lever to bring it back down. I wondered if any of you have done the suggested conversion to the joystick valve, or if you found a way to repair the original valve? I like the idea of the conversion- but have one question- Would this also eliminate the pressure relief valve mounted on the loader arm and fed with hoses from the SCV valve?

Welcome to TBN

Your setup looks like the picture below correct?

I think your best bet is to convert to a new joystick valve, get rid of the hard-lines, mount the new valve in a convenient location, then feed it with hoses.

You can probably do it for about $350, and you will have a modern style valve.

This would be a nice valve: https://www.surpluscenter.com/item.asp?catname=&qty=1&item=9-7401

 

[Tx Jim]

struell
If current control valve spools are in neutral position but loader function moves on it's own accord the only "repair" is a completely new control valve.

 

[J_J]

You didn't say if your system is open or closed center hyd system.

If the centering springs are weak or the nut loose on the spool end the spool could be sliding toward the lift side.

Centering springs can be adjusted or replaced.

If the spool is centering, there should be no fluid coming out the work port, and if there is fluid, then the spool is worn beyond use.

If there is an external relief on the loader lift arms, it is there for extra protection. You may want that adjustable relief depending on the pressure rating of the cyl pressure verses the pump pressure..

If your hyd system is CC, there is probably one relief valve close by the pump.

 

[Tx Jim]

JD 750 is open center hyd's.