Case 310G dozer hydraulic problems

[Jonathan Thomas]

Thank you. I would appreciate that. Got my pressure
tester, but am going to have a special adapter to make
it work.

 

[WilBury]

You can likely just drill & tap for 1/4" pipe thread an existing elbow or do it to a new one.
Don't forget to get a steel plug for it when you're done testing.

This post was edited by WilBury on 08/13/2023 at 08:39 am.

 

[WilBury]

Sorry for the quality, very old document. Hopefuly you can zoom in to read it.

Just out of curiosity, where are you located?

 

[Jonathan Thomas]

Thanks, I really appreciate your help. Located just
outside of Nashville Tennessee.

 

[WilBury]

Trying to send you contact info thru Classic view so I can email you the docs.
Might have to check your spam folder for it.

This post was edited by WilBury on 08/14/2023 at 06:31 am.

 

[AJ.]

Take out the main regulator valve and have a good look at it esp the bottom section where the valve seats in case any debris are holding it open, that is the only valve on that machine that can knock out all the functions, it is unlikely that all the check valves are stuck open so forget about them, when I answered your first post I took it that it was only the lift that was an issue but since you have no movements at all the main regulator valve is the first to go for, no need to alter the pressure so undo the valve by the biggest nut where it screws into the chest, make sure all the o'rings on the body are good
AJ
[img]https://forumphotos.yesterdaystractors.com/photos/mvphoto108572.jpg[/img]

 

[WilBury]

I'm pretty sure you're right AJ. Something not kosher with the main relief.

If anyone's interested I can email them a copy of the following:

Bulletin 1552-B9, Revised December 1964
Parker Maintenance Instructions for VDP12 Parallel Circuit Hydraulic Control Valves

I doubt there's a copyright issue.

Also available on the web is:

https://www.parker.com/content/dam/...atalogs/Cat-2400_7-00/Cat2400-VDP-VY-VPRP.pdf

 

[Jthomas1970]

Thanks for the suggestion. I have already taken this valve out and cleaned it. Minimal debris in it and all appeared good. I left the adjustment as it was and did not try to adjust it. Thought I would
check pump pressure first. I ordered a pressure gauge kit but haven't had the time to check it as yet. Hoping that will tell the tale. Thanks again. Jonathan

 

[AJ.]

If you are sure the regulator valve is OK then it is fair to assume the pump is not making pressure, is it getting oil, could there be a blockage in the feed pipe, the hydraulic circuit is fairly simple, oil from the tank flows to the pump, the pump pushes it to the control valve, it passes through the control valve and goes back to the tank, when a lever moves a valve the oil is blocked from returning to the tank and sent to whatever function is selected, the oil pushes on the piston in the selected cylinder/s and moves the load, when the piston reaches the end of it's stroke the pressure builds up and pushes the regulator relief valve open allowing the excess pressure to escape and return to the tank, the mystery with yours is it was working OK before the restore, can't see how the pump or valves would go wrong while the machine was resting, possibility pump or pump drive.
AJ

 

[WilBury]

The thing with this system, at least with these open-center control valves anyway, is that no significant pressure can build unless that main relief valve is seated closed.
It's appreciated that you've already had it apart & cleaned but I think it's worth another look paying special attention to the internal O-ring(s), backup ring, as well as condition, location & movement of springs & seats and both plungers.

This post was edited by WilBury on 08/24/2023 at 08:11 am.

 

[Jthomas1970]

A big thank you for all that responded with suggestions and help. I finally got the adaptor I needed to check the pump pressure. Barely any pressure! I have now drained the fluid out, taken the pump off,
and will be taking it into a local hydraulic repair shop for evaluation this morning. I will keep you all informed as to what they find out. Again, thank you all!

 

[Jonathan Thomas]

I will take it back apart and have another closer look.
Maybe I missed something. Thanks for the
suggestion..

 

[WilBury]

Good man. As long as she's drained of fluid, may as well. Forgive me if you know this, but you need to take out the whole relief valve (biggest wrench) to access both plungers.

 

[Jonathan Thomas]

Took the Relief Valve back out and looked it over
pretty good. Didnt see anything that I suspect would
cause total lack of pressure. O rings look good and
filter is clean and open. Ive attached a couple of
pics. Does anyone see anything that Im missing?
Many thanks!

 

[WilBury]

It's all there. I didn't try to remove the plunger/poppet seats either.
It shows some wear all right but looks serviceable.
The small O-ring looks like it needs to be replaced, & maybe the large one too. That small one will need to match up properly, not sure if it's a standard size.
I don't recall if the original backup ring is a split-ring style that can be easily removed but with the O-ring out of the way you'll be able to clean it up nice & should be able to tell.
I've no experience with the filter screen, mine didn't have one. The book does say not to remove it but to verify that the bleed orifice to the pilot plunger is not plugged.

 

[Jthomas1970]

Bleed orifice is clear and filter is clean. I will remove the o rings and see if I can replace them. Have not heard back about my pump as yet. Thanks.

 

[WilBury]

Ring sizes are all listed here.

https://www.mycnhistore.com/ca/en/c...56875BD6/8CCD6496-EFBE-E111-9FCE-005056875BD6

 

[AJ.]

Make sure the drive spline on the pump and the flange are good, really nice restore you have done, it's a pity you are having this aggro with the hydraulics, you will get it sorted and have many happy days dozing with Casey, I think that line of Case machines were looked very nice to the eye.
Good luck
AJ

 

[Jthomas1970]

Thank you. Has taken a few years off and on to get it to where it is now. Never dreamed that the hydraulics would cause this much trouble. The splines on pump and pulley are fine and working. Still waiting
on pump repair. Hope that is the problem. I'm looking forward to running it.

 

[WilBury]

???