John Deere 401C Hydro trouble

[Tx Jim]

OOPS me too thought he meant Rockshaft when he stated RS. Now it's "I SEE stated the blind person".

Ditto on rear scv is leaking internally. Simple test with scv return line disconnected from tractor, scv control lever in neutral start engine & if oil exits open line you have located at least 1 & "hopefully all" of your tractor's hyd problem.

 

[85bj60]

Oops! I ASSUMED RS was for RockShaft. Also called 3pt hitch.
I use SCV, for Selective Control Valve(s), for the valve(s) that control quick connectors. What you connect your chute rotator to.
So when you blocked off the rear fitting of the PCV, everything was fine?
When you connected rear fitting back to SCV(s), you had problems?
Sounds like a SCV is leaking internally back to sump. bleeding pressure off?
Is/are the SCV(s) original to the tractor? Maybe someone replaced them with ones for open center hydraulics?

I reconnected the PCV with the Rear SCV blocked off just to remove it from the troubleshooting. No pressure to FEL and steering, so problem still exist. I was told the PCV housing is worn and it will be put back to cover my two passages along with it been blocked off. I will have the Rear SCV connected to see if I still have function, I pray that I do! If not, will a TEE on my bypassed hose connections to FEL work? I was told it won't work but I believe so unless it's defective. The Rear SCV is original to this tractor.

 

[Zebrafive]

I reconnected the PCV with the Rear SCV blocked off just to remove it from the troubleshooting. No pressure to FEL and steering, so problem still exist. I was told the PCV housing is worn and it will be put back to cover my two passages along with it been blocked off. I will have the Rear SCV connected to see if I still have function, I pray that I do! If not, will a TEE on my bypassed hose connections to FEL work? I was told it won't work but I believe so unless it's defective. The Rear SCV is original to this tractor.

Blocking rear SCV(s) ruled them out.
No pressure to steering says the pressure is being bleed off.
It could be loader, rockshaft, or PCV bleed to case.
Next (easiest to do) is block the fitting to the loader and see if you have steering.
IIRC you said you connected the pressure in for the PCV directly to the loader out line of the PCV, and steering loader worked? So I doubt the loader is the problem, but check and rule it out.
If the loader is ruled out, that only leaves the rockshaft and PVC bleed off to case.
My guess is with the worn housing, oil is getting around the valve assembly that is inside. There is an aperture, key 12 that allows a small amount of oil to go through the valve. One of the two holes on mounting side of the PCV is to bleed off the oil back to sump so the valve does not become hydraulically locked.
So next block ONE of the two passages to case. If you block the passage to the rockshaft and still have a problem, you will know too much oil is going through the bleed off passage. If you were to block it, the valve would hydraulically lock and stop moving. If that happens you can easily remove plug 17 and remove the valve parts. Reinstall the plug and the PCV housing will become a giant TEE.

 

[Tx Jim]

Z5
I have considered removing PC spool valve in the past but never followed through. If spool is removed what keeps oil from going directly to sump?

Never mind I reread your post & see where you stated "block 1 passageway"!!

I agree with Z5 & think power steering would operate fine as long as no other hyd control was activated while turning steering wheel.

 

[85bj60]

Blocking rear SCV(s) ruled them out.
No pressure to steering says the pressure is being bleed off.
It could be loader, rockshaft, or PCV bleed to case.
Next (easiest to do) is block the fitting to the loader and see if you have steering.
IIRC you said you connected the pressure in for the PCV directly to the loader out line of the PCV, and steering loader worked? So I doubt the loader is the problem, but check and rule it out.
If the loader is ruled out, that only leaves the rockshaft and PVC bleed off to case.
My guess is with the worn housing, oil is getting around the valve assembly that is inside. There is an aperture, key 12 that allows a small amount of oil to go through the valve. One of the two holes on mounting side of the PCV is to bleed off the oil back to sump so the valve does not become hydraulically locked.
So next block ONE of the two passages to case. If you block the passage to the rockshaft and still have a problem, you will know too much oil is going through the bleed off passage. If you were to block it, the valve would hydraulically lock and stop moving. If that happens you can easily remove plug 17 and remove the valve parts. Reinstall the plug and the PCV housing will become a giant TEE.

I'm learning more & more on this PCV. Rereading this post is exactly you're describing. So now loader steering is working fine but I lost my rockshaft function(notice that when I went to attach the snowblower), the PCV is completely disconnected except for the Rear SCV. By troubleshooting the rockshaft, it all became clear of those 2 holes in the transmission is all about. Thanks for the tip on blocking the holes one at a time, this would point a finger on the culprit!

 

[85bj60]

Ok, I plugged the weeping hole(and leaving the valve in the PCV, couldn't justify removing it yet) and I'm still in my woes of no FEL operation. I'm thinking of adding a two way 12V valve to split the two functions, FEL & RS. Or maybe a hydraulic one....
I'm in the winter season and playing around with this hydraulic system is starting to get long & cold!

 

[Tx Jim]

I know orange marked orifice supplies scv. Does orifice marked green supply FEL? If I was attempting to repair the hyd problem I'd just eliminate(bypass) pressure control valve by capping colored & inlet orifices & tee lines together.

 

[85bj60]

Yes, the orange feeds the SCV. The green is capped and it's for the backhoe and #3 is pump feed inlet which could be same as green. #18 feeds the FEL. The more I observe the system, the more can be the culprit( weak pump, blown or leaking RS seal, etc..,)
I tried bypassing the PCV but I lose the RS(3 pt system) which I need for the snowblower. I might still cap it and raise the 3pt manually just off the ground and do without the RS for now.

 

[Tx Jim]

Yes I forgot you needed 3 pt. If rockshaft valve seals are leaking one should see moving oil in hyd filler hole behind seat when 3 pt is raised & engine is running.

 

[85bj60]

Yes I forgot you needed 3 pt. If rockshaft valve seals are leaking one should see moving oil in hyd filler hole behind seat when 3 pt is raised & engine is running.

Super frigid weather at this moment and warming some by the weekend. I'll do a inspection when I fire it up. I could try to remove the internal valve in the PCV while I'm at it, got nothing to lose to try it. Any suggestions for a two-way valve I'm thinking of implementing into the hyd system?