953c hydraulic pump

[JDirt]

Got a new to me 953c a few weeks ago, loader stopped, I put gauges on the 2 ports under the sight glass, got no pressure, needle doesn't even twich. Have I narrowed it down to a bad hydraulic pump, or is there any other possibility? Serial number is 2ZN00795.

 

[Nige]

When you say "stopped" do you mean the implements stopped working.?
These two prssure taps you mean.? The bottom one of the two is implement pump supply pressure.
Agreed zero pressure sounds like the pump but have you cut open the filter just to see whether it's full of debris.? It's a vane pump so if it has let go you should see plenty of evidence.
Attached a couple of documents that might help you.

 

[JDirt]

Thanks for the reply, yes the implement (loader) stopped working, tractor travels normally.
I tested both of those test ports in the picture, neither made the needle on the gauge move.
I have not cut open the filters, I will do that next trip (machine is 50 miles from home). Would one of the spin on filters catch all the debris of a spent pump? Is there a flush procedure when changing pump?
I am going to try to find a tag on the pump so as to order the right one. One parts man I talked to this morning found a part #9t5619, which I think is a drive pump, the # I keep coming up with is 149-4699, so I'm going to try to get eyes on it and make sure. Is there an easy way to get to this pump?

 

[Nige]

149-4699 is the implement pump.
If the implements were working normally and stopped suddenly what about the possibility that the pump shaft could be broken.? If the pump has broken up internally a fair bit of the debris should be in the filter IMO.
According to the Service Manual access to remove the pump is by removing the floor plate.
I hope CMark chimes in. He's the HEF resident track loader expert and should be able to shed some light.
See attachment.

 

[Cmark]

Have a look at the main pressure relief valve. It's screwed into the manifold below the oil filler and easy to get to. I would say there's a >50% chance you will find it stuck open or with blown O rings.

 

[Nige]

Chris, Could a failure of the 24v solenoid valve on the PRV also cause it to play silly buggers.?

 

[Cmark]

Unlikely, in my experience. That dual-pressure arrangement was only fitted to early machines and may even have already been replaced with a non-variable manifold.

 

[JDirt]

I'm pretty sure mine doesn't have the solenoid on that block, just the relief valve and the test port.
So when I pull out the relief valve, is it obvious when it's stuck or am I going to have to disassemble it?
I'll make a trip to the machine in a day or two and try to determine just what I've got to deal with. We've got a couple jobs going closer to home I have to tend to first.
Thanks for the help.

 

[Cmark]

You might get lucky and see something jamming it open.
Taking it apart isn't really a biggie though. Just mark the threads, count the turns or do whatever it takes to put it back together the same way.

 

[Nige]

It appears as though the OP has a pressure gauge so it wouldn't be too difficult to check the setting after pulling the valve apart. Test & adjust is in the attachment in post #2.

 

[JDirt]

I cut the spin on hydraulic filters apart, they are spotless, I'll pull the main relief valve next and report back.

 

[JDirt]

Pulled the main relief valve, disassembled, all looked well except for some aluminum shavings on the outermost part. I am very sure these were produced when I unscrewed that outer aluminum section.
Everything else was clean and it all went back together.
We removed the floorboard and front belly pan in preparation of removing the pump.
Is there a less messy way of draining the hydraulic tank?

 

[Nige]

Is there a less messy way of draining the hydraulic tank?

Manual simply says.....
1. Remove the hydraulic tank filler cap. Check the cap seal. Replace the seal as necessary if it is cut or damaged.
2. Remove the strainer. Wash the strainer in clean solvent.
3. Remove the bottom tank guard cover.
4. Remove the drain plug. Open the drain valve and drain the oil into a suitable container. Close the drain valve when all of the oil is drained.
5. Install the drain plug.

 

[Cmark]

You will need good access from underneath to (easily) remove the suction tube bolts. I suggest driving it up onto some timbers to give yourself more room. Or put it over a pit.

Sudden vane pump failure not accompanied by noise or debris in the filters is uncommon though.

 

[JDirt]

The pump does make a whine a little bit, like a pump after an oil change purging air out. Any possibility there is an air lock somehow? I've cracked tilt cylinder hoses loose, operated and no oil came out.
Is there a shaft or coupling that can break? If that were the case, I don't think there would be a whine at all.
Either way I'm going to try to get that pump off today, I'll report back.

 

[Cmark]

Failure during use won't be due to an airlock, unless the tank was empty. Even then this is an open centre system and so is self-bleeding.

It's possible a shaft or coupling could fail.

If you have some pump noise a broken rotor or cam ring is likely.

 

[Cat977]

You might want to cut the top and bottom off the filters and open up the pleats. The bottom of the pleats seem to fill up first.

 

[Nige]

Cut a section out like this then squeeze it in the vice before looking in the bottom of the pleats. (Skip to 3 minutes if you just want to see the cut & inspection process)

 

[JDirt]

I cut apart the filters and still didn't find much, what I did find was probably from my sawzall. Probably not the best tool for the job.
Got the pump pulled out, disassembled and looks like the shaft was spinning inside, didn't go any deeper.

 

[JDirt]

Inside the cartridge