4430 hydraulics leaking down

[cdsloop]

Our 4430 is set up with 3 sets of hydraulic outlets. It is leaking pressure internally while running. Whatever is hooked to it will leak down, whether the baler, mower, disk, etc. We're experiencing the same problem on our JD 7200 also. Do we need to rebuild the couplers? The most common implement to these two tractors is the 3 pt. hitch disc mower that has a single action cylinder. Is this causing the problems? Any suggestions are appreciated. Thanks.

 

[Bob]

With the 4430, you mean to say it leaks down equally fast with the coupler from the single-acting cylinder plugged into ANY of the nine possible available positions in the 3 SCV's?

The only way a SINGLE-acting cylinder could be at fault in the leaking down is if the cylinder is leaking externally BIG TIME.

 

[cdsloop]

It leaks down with a single or double action cylinder. With the round baler, we have to "pressurize" the cylinder on the door every minute or so, or the door will pop open. I know that it leaks on two of the three sets on the 4430(third set is "old style" JD, not Pioneer so they don't get used often). We do have some leakage externally, but not enough for the rate of pressure loss. Also, rate of leakdown seems to increase the longer we run, which I feel is due to oil viscosity breakdown due to heat.
We switched plugging the single acting cylinder from one side to the other of one SCV, and that helped for a while, but then the other side started leaking down.

 

[Bob]

WOW! That'll cost a few bucks having all three SCV's rebuilt!

Have you checked/changed the hydraulic filter lately... any excessive metal in it?

 

[tim s]

With the 4430 the poppet valves are probably leaking they have a nylon seat on them that goes bad which will cause them to leak"up" if it's the pressure side,,"down" if it's the return side, I usualy replace all 4 when I rebuild a valve,,when the leak they will 'squeel' a little and will heat up also,,It takes about $200 parts to rebuild a valve and a $100 or so labor. As for the 7200 it has a diferent valve.