Case 310G dozer hydraulic problems

Jthomas1970 · Aug 4, 2023

Hi guys. I'm looking for some help with a direction I should go. I have been restoring a Case 310G dozer with six way blade. Hydraulics all worked when it was taken apart a few years ago. Now finishing it
up with new hoses, filters, and fittings etc. Same pump and controls. Appears to be low pressure, but I'm not sure. Lift cylinders work slowly when not connected to blade. When connected, will not lift, nor
pivot. Nothing. If I lift the blade with a hydraulic jack, it will hold it in place, but drop when control is moved in either direction. Have a Cessna pump but don't have a way to check pressure. Believe
it has to be either a pump or control valve issue. Think all check valves are located in the control valve assembly and not in the pump. Any suggestions would be appreciated. Thanks in advance.

tomtinker · Aug 4, 2023

Did you recheck the fluid level after the tank filled up all the hoses and cylinders ?

Jthomas1970 · Aug 4, 2023

Yes, all new fluid and full.

tomtinker · Aug 4, 2023

Did you check for rat nests in the fluid filter? Lol.

WilBury · Aug 5, 2023

A detail most of us have missed at one time or another:

Is your diversion valve, if you have one, fully stroked to dozer position?

AJ. · Aug 5, 2023

Is all the other functions normal, press the blade down will it lift the machine up, have you tested the hydraulic cylinders to see if the oil is bypassing, the hoses are not crossed, it is seldom the control valve gives trouble unless foreign matter has got in the system, so like suggested above check what's in the filter.
AJ

WilBury · Aug 5, 2023

I reiterate. Check your diversion valve first. Easiest & cheapest fix you'll ever see.

WilBury · Aug 7, 2023

Any joy yet?

Jthomas1970 · Aug 8, 2023

I don't think I have a diversion valve. I have the manual, but it doesn't say anything about a diversion valve. I do have a Main Check valve located in the control box. I pulled it out according to the
manual, but it looked fine. I cleaned it and reinstalled, but the dozer does exactly the same thing. I see very little movement for the up control, but nothing else. I do have three check valves, one for
each control lever. I am assuming that they are ok as none of the three work. There was new fluid in the Main check Valve bore, so I know I am getting some pressure from the pump. I just don't know if it is
enough. Any other ideas I can check out? Thanks!

WilBury · Aug 8, 2023

Here's one of the 310G pages from CaseCe

https://www.mycnhistore.com/ca/en/c...32301/cn/8CCD6496-EFBE-E111-9FCE-005056875BD6

It shows an optional diversion valve on the right side battery box. If your machine was converted from a loader, they were mounted on the front left vertical face of the hydraulic tank. Hoses to it must be correctly routed & valve in correct position for things to work.

You might need to find a gauge to properly set your main relief valve. That's where the pressure comes from. If it's set really loose or if it's internal sealing rings are missing or out of place, you'll have very little pressure or worse.

Failing that, something's gotta be hooked up wrong or broken. Pump not positively driven? Gear missing in pump? Pump input instead of output to valve? Tank return connected to pressure line before the valve? Valve cracked wide open internally?

Good luck & please keep us posted.

What manual do you have, the big shop binder?

This post was edited by WilBury on 08/08/2023 at 11:46 am.

Jthomas1970 · Aug 8, 2023

Have the general shop manual for the 310-350 machines. I'm almost 100% sure I have everything hooked up correctly. Pump is shaft driven from front engine pulley and it is turning. Only thing I can think of
now is an internal problem in either the pump or valve control box. Thinking of taking the pump off and taking to a repair shop for evaluation. If not pump, has to be a control problem. Thanks for the help
and diagrams. I will study them prior to pump removal.

tomtinker · Aug 8, 2023

What are you calling check valves? If you have added check valves to the original plumbing that would be your problem.

WilBury · Aug 8, 2023

OK, I have the same manual & will look it over tomorrow.

It might help if you tell us which serial and style of dozer you have. No diversion valve, eh?
I see the pump has check balls that must be present.
Check valves on the control valve just hold a load in the air & protect the valve spools but won't stop deliberate movement.
Main relief valve must be adjusted to the correct pressure & while you're at it, check the pressure setting on the secondary relief valve(s) too.
I bet if you let them take an imprint of your credit card the hydraulic shop will loan you a gauge. You'll just have to convince them you can do it without injuring yourself. Be careful, hydraulic fluid under pressure can kill. Follow all precautions. The manual should show you what pressure range gauge you need, where to hook it up & how to adjust.

WilBury · Aug 9, 2023

So it's a six-way power angle and tilt? Nice machine!
Do you have the hood off? Can you manage a few pictures of the hydraulics and valves?
If it worked fine before, the pump is unlikely to be your problem.
Can you see fluid movement looking in the hyd. filler cap?
Did you at some point back out the main relief valve adjusting screw?
It might be worth a try to turn that srew in a half-turn at a time & see if there's any difference in operation. If there is, get a gauge.
Can anything be heard or felt when you actuate a circuit?
It's really the only thing I can imagine other than a diversion valve thing.

Do poke around that Case parts catalogue online amongst the different models. Lots of info there.
I know the manual can be a little hard to read, patience. I'd like to think there must be another way to adjust the secondary relief valves without a hand pump.
If eventually you run up against a brick wall, a good heavy-duty mechanic will be worth an hour or two to troubleshoot.

This post was edited by WilBury on 08/09/2023 at 05:54 am.

Jthomas1970 · Aug 9, 2023

Thanks for all the suggestions. The filler port is very small, but I will try and look inside. I haven't done that yet. I left the same setting on the relief valve when I cleaned it. I haven't tried to
adjust it as yet. That maybe worth a try. I ordered a pressure gauge set last night. Thought that would be worth a try before pump removal. I have some general pics of the machine, but not of the
hydraulics. Will take some and the serial number and try to post here. Thanks again for all the help.

Jonathan Thomas · Aug 9, 2023

These are the pics.

WilBury · Aug 9, 2023

Wow, looking good, not just a two-gallon-overhaul.
Aha, the early model.

It's too bad they didn't beef up the whole rear of the machine for a ROPS on the 310E like they did for the 310G. I'd have to hire an engineer.

With that 3-way you could have a ball in a mountainside forest.

D33929 Parker Hannefin VDP-12 control valve. I know it well. Keep the float mechanism clean & greased. In that mounting position new 5/8" spool wipers & O-rings are advised. Check rear spool caps yearly for water. Mine eventually separated a spool from scoring & sticking.

I had to take my main relief valve into a specialty shop where they machined new back-up rings and whatever was necessary to refurbish it. Couldn't buy 'em, & that was a long long time ago. At least you can easily take the whole valve in.

Can't really tell much from the photos. Pretty sure the tubes locate themselves but only you know which of those new hoses go where.

Jthomas1970 · Aug 11, 2023

What are you referring to when you talk about the Float mechanism? I don't see it in my manual.

WilBury · Aug 12, 2023

Figure 14 page 4021-10
Figure 31 page 4021-21
page 4021-22 Four position spools & detent assy
page 4021-24 Four position spools & detent assy
page 4021-25 Installation

WilBury · Aug 12, 2023

I have a maintenance manual for the VDP 12 valve series. When I find time, I'll digitize for ya.

Case 310G dozer hydraulic problems

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