Hyd. Control Valve

[ROADMAN1]

The Hyd. Control Valve on my 1957 Ford 850 loader (see attached photo) is allowing hyd. fluid to bypass causing the bucket and arms to leak down. Can this control valve be taken apart and "O" rings replaced and if so how do I get it apart or should I remove the Valve and have a Hyd. repair shop rebuild it.

Thanks
Clay

 

[TheOldHokie]

A lot depends on what is wrong with the valve. If the spools or block are worn it is unlikely it can be repaired. A new 2 spool loader control valve will run you about $190 - probably not a whole lot more if any than the cost of a repair shop. How did you determine it is the valve leaking and not the cylinders?

TOH

 

[ROADMAN1]

I've been able to work the lever a little and stop it from leaking down as fast as it is now. This does not work now so I assumed it was the control valve. Is there any way to determine if it is the cylinders or the valve?

 

[Jock(OR)]

To determine if the leak is in the valve spools or because the cylinder piston packing is leaking from the "up" side to the "down" side do this: raise the bucket and place some sort of blocking so no one could get hurt if the bucket falls rapidly. Remove the hydraulic line that dumps the return oil back into the sump. BE VERY CAREFUL TO IDENTIFY THIS LINE PROPERLY!!!! Several times a year a professional mechanic gets killed because he removed the wrong line and the bucket was not blocked for safety. With the line draining into a container, allow the weight of the loader bucket/arms to bleed down. If very little or no fluid comes out of the return line, then the piston packing is bad. If there is a flow out of the return line that reflects the rate of drop of the loader bucket, then the valve is leaking.

Before you take the valve apart, determine if there is a "load check" relief in the system. Often the relief will get held open a little by a piece of dirt or damage to the seating surfaces. The procedure for cleaning the reliefs is different depending on who made the valve, so it is too involved for me to try to describe.

 

[TheOldHokie]

(quoted from post at 16:38:04 05/15/12) I've been able to work the lever a little and stop it from leaking down as fast as it is now. This does not work now so I assumed it was the control valve. Is there any way to determine if it is the cylinders or the valve?

• [*:851f0d9a8f]Raise and block up the loader arms. [*:851f0d9a8f]Shut off the tractor and disconnect the lift arm cylinder "extend" hose(s) from the control valve and cap them. [*:851f0d9a8f]Now remove the supports under the loader arms - if the loader arms drop the cylinders are leaking internally. [*:851f0d9a8f]Repeat test for the bucket cylinders if it is leaking down.[/list:851f0d9a8f]
  TOH

 

[ROADMAN1]

Thanks TOH and Jock(OR) Great advice. I'll do this check this weekend. I never would have thought about this method of checking for internal leaks on a Hyd. cylinder.

Thanks again

Clay