Cat 416 D rubber tired loader /backhoe

[Fishfiles]

Cat 416 lost 50 % of pressure to front fuctions of boom and tilt as it will only pick up a half of bucket of trash and not lift itself off the ground with front bucket , the rear boom and out riggers are not effected at all , the pump is a one stage that goes into tee and feeds both the rear and front controll valves so you would have to think that it's not a pump problem , did find blown o ring and back up ring on one of the curcuit relief cartraiges , but that didn't fix problem , on the front valve the first bank looks like it is a compensator spool , which slides smoothly , there is a what I think is a pilot hose going into that bank which probally triggers the spool to shift , I don't have a manuel and not totally familiar with this machine , -----hs anyone seen this problem before ----fishfiles

 

[Tazza]

Sounds like an odd setup. Are you able to hook a pressure gauge to the problem section? it sounds like you still have a stuck relief valve. Or a weak spring for the valve not allowing you to get full pressure.
Depending on how the oil suply works as you said its split i assume each control block has a seperate relief? If they look the same you could try swapping them to see if its the problem?

 

[Fishfiles]

Sounds like an odd setup. Are you able to hook a pressure gauge to the problem section? it sounds like you still have a stuck relief valve. Or a weak spring for the valve not allowing you to get full pressure.
Depending on how the oil suply works as you said its split i assume each control block has a seperate relief? If they look the same you could try swapping them to see if its the problem?

Order a $330 manuel today for tommorrow and had a chance to talk with 3 different Cat mechanics , they all feel from what I told them it is a resolver or a check valve , both of which are under are on the back side of the controll valve which you get to thru a hole in the side the frame next to the rear tire , Cat isn't going to make it easy , well at least I have a few ideas to work with when I get the manuel and go back , I didn't hook a gauge up as I can see the pressure is there in the back and not in the front , the Cat told me it has to be in the valve if the rear is working fine , the reliefs I took apart and cleaned and replaced o rings and back up rings , but you are right about it could be a weak spring , the thing that steers me away from the reliefs is both tilt and boom are effected and there is no relief for the entire bank , the reliefs are on each spool , hope to get it figured out soon

 

[Tazza]

Order a $330 manuel today for tommorrow and had a chance to talk with 3 different Cat mechanics , they all feel from what I told them it is a resolver or a check valve , both of which are under are on the back side of the controll valve which you get to thru a hole in the side the frame next to the rear tire , Cat isn't going to make it easy , well at least I have a few ideas to work with when I get the manuel and go back , I didn't hook a gauge up as I can see the pressure is there in the back and not in the front , the Cat told me it has to be in the valve if the rear is working fine , the reliefs I took apart and cleaned and replaced o rings and back up rings , but you are right about it could be a weak spring , the thing that steers me away from the reliefs is both tilt and boom are effected and there is no relief for the entire bank , the reliefs are on each spool , hope to get it figured out soon

Are you sure they are relief valves on each spool? they should be load checks. The lift function sometimes has a relief to prevent you from over loading the lift cylinders and causing something to burst.
Most normal hydraulic systems just run one relief valve.
I hope you find the problem easily.