Lift/Tilt cylinders both drifting down?? Any suggestions

[TNHOTROD]

Machine is a 763 the control valve is the setup that has the Bics assy. mounted on the face of the control valve with six bolts. Control valve has had new seals and been cleaned . Checked everything as far as orings and visually looked at all the parts. Put new seal kits in both lift arms. Any suggestions??

 

[Tazza]

If you replaced the O-rings and ram seals, the only thing lief is the load checks. The seats and poppets may be worn allowing oil to by-pass. Just how fast does it leak down? a few inches per hour without a bucket is acceptable.

 

[Fishfiles]

Also something to ponder , The boom emergency lowering valve will let the boom leak down if it is leaking internally or the spool is bent and partially open , but should have no effect on the tilt , did you maybe damage the piston seals on installation

 

[TNHOTROD]

Also something to ponder , The boom emergency lowering valve will let the boom leak down if it is leaking internally or the spool is bent and partially open , but should have no effect on the tilt , did you maybe damage the piston seals on installation

It leaks down quick within 10-15 secs. I was careful with the rebuild kits for the cylinders, so i dont believe it to be the cylinders. i took both lines off the emergency valve and plugged them so i believe that eliminates that . Help ?? Any more suggestions??

 

[Tazza]

It leaks down quick within 10-15 secs. I was careful with the rebuild kits for the cylinders, so i dont believe it to be the cylinders. i took both lines off the emergency valve and plugged them so i believe that eliminates that . Help ?? Any more suggestions??

With the boom in the air, shut the machine down and push your heel down, see if it stops. If it does, it sounds like your centering spring is broken or not holding centre. For it to drop that fast, i can't see it being a load check or even a bad piston seal in the rams.

 

[Fishfiles]

With the boom in the air, shut the machine down and push your heel down, see if it stops. If it does, it sounds like your centering spring is broken or not holding centre. For it to drop that fast, i can't see it being a load check or even a bad piston seal in the rams.

Yeah , 10-15 seconds is coming down pretty fast , did you maybe reseal the controll valve spools recently and maybe put the seal washer in backwards , maybe the detent balls and springs are messed up , , Tazza's idea with the foot pedal will tell you if that could be the problem , I have seen controll valves have cracks inside the bore before , but it's pretty rare

 

[TNHOTROD]

Yeah , 10-15 seconds is coming down pretty fast , did you maybe reseal the controll valve spools recently and maybe put the seal washer in backwards , maybe the detent balls and springs are messed up , , Tazza's idea with the foot pedal will tell you if that could be the problem , I have seen controll valves have cracks inside the bore before , but it's pretty rare

Seal washer?? Are you talking about the blue/green seals at the end of the spools? I installed the new seals with the lip towards the inside. When you have seen the control valve cracked has it been where you can see it ,if its on the bench??
Thanks for your help..

 

[Tazza]

Seal washer?? Are you talking about the blue/green seals at the end of the spools? I installed the new seals with the lip towards the inside. When you have seen the control valve cracked has it been where you can see it ,if its on the bench??
Thanks for your help..

That was the correct direction for the seals.
Cracks can be hard to see, i'd doubt you could see them simply looking in the ports.
Try lifting the arms and using your heel on the lift pedal, see if it slows or stops.