Cat 426c ex hoe has no ex hoe retract power. I removed the hose on the base end of cylinder to be sure piston seals weren't leaking past. No fluid from cylinder, but hose is squirting coming from valve! I looked at parts book and cannot figure it out from pictures. What should I get for parts to fix this and any dos and don't on spool valve repairwork?
You could swap the relief cartridges. You need to be more specific on when oil comes out where when which function is activated
Which cylinder? the bucket, stick, or boom? So the cylinder is stuck extended? If you retract it manually (winch etc.) does it EXTEND when you pull the control to RETRACT.
When I push retract,fluid comes out of the hose going to base end of ex cylinder, that side should be open to return during retract according to my thinking. Clear as mud! During retract fluid flow should be going to rod side of cylinder,which it does but not with force so to speak.
Extend works perfectly, lifts machine off the ground. Retract works just barely.
Also noticed the ext hoe will creep out after sitting for a few days. Are there o ring s that are easily replaced in spool valve? Wouldn't a relief valve fail in both directions?
Yes, but that could be the pressure on the return that is pushing the fluid out... Each function has it's own relief to protect that part of the circuit from overpressure when the valve is closed.
So it has two relief valves in this valve that control ex hoe? Still don't see any reason it should be spraying fluid from The hose that comes from the valve meant for base end but taken off .
The valve is opening that port up to the return side. If return side pressure is greater than atmospheric you will have oil coming out. You should test the cylinder. The piston may have come loose
I will swap hoses today to see what happens.
Swapped hoses,problem moved to extend,definitely valve issue, any ideas?
Or pull the retract one only and tear it apart. Mark it, or write down the number of turns if it's adjustable, you don't want to change the setting any more than possible.
Yeah. Other possibility is a load signal problem. resolver in the Cat manuals
I am a novice for sure but eager to learn. No manual! Does it have two resolvers on this valve? Are there o ring on spool that could be bad and replacable? Thanks for the help fellas!
Yes, but that wouldn't cause your problem. The spool is metal to metal seal, the o rings just seal the ends. If you don't have a manual to show you the relief valves/cartridges, search images for a diagram that looks like your valve. Especially the plugs that you don't see the purpose of. If you aren't comfortable with the reliefs, forget about the resolver for now.
Are the relief valves under the big 12mm plugs?if so should I swap them and see if problem moves?
No, that sounds resolver related. I'd find a diagram of a "cat backhoe valve" that looks like the one you have, take off the relief valve for the function that doesn't work, mark it so you don't change the setting when you put it back together, and take it apart looking for something jammed or broken.
took out the 12mm plug on top, nothing under there. guess I will pull out 10mm plug on the top and see if theres something obvious , maybe broken spring? Looks like it is a spool valve sitting on a spring in parts picture. I don't find a relief valve listed in parts book, does list a resolver.
this may help
Thanks for diagram, mine has what look like dummy plugs where your picture shows relief valves. The plug I pulled on top had two or ing . One was at the end and one near the other end about 1.5" apart. Maybe the plug on bottom has a damaged o ring allowing oil to get to a relief passage that it's not supposed to. It appears that a broken spring would affect both directions if I am seeing it right.
Here is a parts pic of the extend valve. You should look at the resolver number 20 . Check the seals and the inside check ball.
I removed resolver, found second o ring torn. Couldn't find the inside checkball? could have a ball fallen out when I dropped valve, lots of fluid came raining down so I could have missed a ball! Guess I will get new o rings and see what happens depending on what you guys have to say. Thanks for all the help so far, its nice having people share knowledge with me!
I have an old parts book picture that shows only 3 seals on resolver, pic above shows 5 ,should I go with that or call it in to the yellow god(CAT) tomorrow to see if its been superceded?
Just get a new resolver, comes with orings and about 50 bucks if I remember correctly.
picture is showing orings plus back up rings
Ordered a new resolver and some orings for plug I removed and old resolver for a spare! bill was about 60 bucks , will install tomorrow night and report back.
It works great! Thanks a lot for all the help.