Tc33d with 758c (6/00) hydraulic issues

[Mjl1226]

Tc33d with 758c (6/00) hydraulic issues
I recently purchased a used 03 TC33D with a 578c backhoe. The problem that I'm seeing is that the backhoe seams to lack power and if I don't lock the boom and outriggers even when the tractor is running they creep down. My first thought was that the pressure relief valves a going. I spoke with a local tractor shop and the said most Likely the gresen valve I scraping out.
Any thoughts would be greatly appreciated.
Michael

 

[J_J]

What kind of test have you done?

You can remove one port hose and try to push fluid through the seals. If the seals are leaking, you will see flow.

If you can determine the cyl are good, then raise the boom up and see if the valve spools are leaking.

To double check that, insert some needle valves in the work ports and raise the boom and shut off the needle valve.

What rpm are you running the engine when using the BH?

If you install a 3000 psi pressure gage, you can use it to troubleshoot and monitor the hyd system. The pressure relief valve is not a factor with no hyd being used, except if there is crud between the the poppet and seat.

Are all your relief valves set to specs?

 

[Mjl1226]

On which line would I install the pressure gauge? Not sure if the reliefs are set to spec. The dealer I bought the tractor from took it on trade and said he did a complete service and checked the hydraulics but did not specify what he checked. I usually run at 2300 - 2500 temp for the hoe. I have operated many pieces of equipment over the years and taken care of them from an operators stand point but this is the first that I have owned. So please pardon my ignorance but when you say valve spools are you taking about the accrual control valve assemblies?

 

[J_J]

Yes. The spools are the shiny pieces of metal that the lever is attached to and slide back and forth to route the hyd flow.

I would recommend to install a 3000 psi hyd gage in a tee inserted in the IN port of the first valve after the pump, placed where you can see it to troubleshoot and monitor the hyd system.

Once installed, the hyd gage will show when you have pressure, and the pressure that is generated by the load.

You can check your valve relief pressure by fully extending or retracting the cyl to max and holding to see max pressure developed by the pump and the hyd components.

You can then adjust if appropriate.