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.
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.
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?
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.
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.
Chris, Could a failure of the 24v solenoid valve on the PRV also cause it to play silly buggers.?
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.
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.
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.
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.
I cut the spin on hydraulic filters apart, they are spotless, I'll pull the main relief valve next and report back.
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?
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.
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.
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.
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.
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.
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)
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.
Inside the cartridge
She broko..........
At least you’ve found it. I had a pump fail on a 963D, (axial pump) slipper plate failure. I was worried about where the debris had got to, but did a double oil and filter change with the new pump and never had any more problems.
Yes, I was actually relieved when I found it. I hate taking something apart and not finding anything wrong and having to dig deeper.
Do you think the debris was contained within the pump area? ?
Doesn’t look like there’s much fine debris, which is a plus.
Did you happen to notice whether or not it was a Cat pump.? The failure mode is somewhat unusual, to say the least.
Thinking the same. Had something jammed the rotor?
ih100 it does seem like a sudden urge to stop may of happened. I've never seen it happen mind you, but there was a Don't dead head a Pump rule back at the power plant. Most every hydraulic pump I ran into had a internal relief valve to prevent a hydraulic lock. It does look like the pump jammed. I suppose this is a cartridge exchange with no peeks inside.
From the photo of the shaft that pump would likely not be eligible for Core Credit against a Reman anyway.
I assume it's a cat pump, seems like the debris did not get out. So far I have only found a new pump for $1566. I'll disassemble my pump and take some pictures.
That doesn’t sound too bad a price. I think a new pump for a 63D was around £4000 fifteen years ago, direct from Cat Grimbergen
Agreed. I'm seeing $1625. There is no Reman option, quite likely because it's a vane-type pump.
Before you start up with your new pump i would do either of two things 1/ Back off your main relief valve a couple of turns to protect your new pump and then set your relief valve 2/ if you dont back off your relief valve at least hook a gauge and feather your controls and observe your pressure build to make sure it is in range i have seen too many cowboys play with the relief settings over time, chasing more performance from there machine and not understanding what they are doing Good Luck Mark
Good advice, I will do just that, got my new pump from CAT this morning, just have to make time to put it in.
Got the old pump disassembled here's what it looked like
New pump is installed and working, pressure was 3100 psi, I turned the relief valve maybe a quarter turn, now it's 3800, thought maybe I should find the correct procedure for adjusting before I went any further. I'm not real sure about which part to turn, which is the jamb nut and which way to turn.
Spec is 3485 +/- 50psi. There are two types of main relief valve. Please post a photo of the valve you have on your machine so we can see which type it is.
I think there is some outfit on FleaBay that sells glue to fix that pump! Just kidding, I agree getting the main pressure right is important. I might be tempted to disassemble the relief valve to make sure there isn't some crap in there that could cause it to not relieve correctly.
Here's the main relief valve I did disassemble it before changing the pump, it was clean.
I'd like some confirmation but from what I can determine your relief valve is missing a locknut. There are two settings on that valve, low & high. The High setting, which should be done first, is made by loosening the locknut and using the arrowed adjuster, referred to as "B" in the procedure. The Low setting is made by loosening the thin locknut (arrowed red) that I think is missing on your valve, and an allen key in the end of the spindle. Complete procedure below. Note: Always adjust the HIGH setting before adjusting the LOW setting. 1. Connect a 50000 kPa (7250 psi) pressure gauge to pressure tap (B). 2. With the engine at HIGH IDLE, raise the bucket to maximum height. 3. Hold the lift control lever in the RAISE position and observe the pressure gauge reading. 4. With the tilt control lever in the HOLD position, the main relief valve should be at the HIGH setting. 5. With the tilt control lever in the TILT BACK position, the main relief valve should be at the LOW setting. 6. The correct HIGH pressure setting of the main relief valve is 24000 ± 350 kPa (3480 ± 50 psi) at a flow of 130 ± 6 L/min (34 ± 1.6 US gpm). 7. The correct LOW pressure setting of the main relief valve is 21400 ± 350 kPa (3100 ± 50 psi) at a flow of 130 ± 6 L/min (34 ± 1.6 US gpm). 8. If an adjustment is needed, the HIGH setting should always be adjusted before the LOW setting. After adjusting the HIGH setting, the LOW setting can be adjusted. 9. The HIGH setting of the relief valve can be changed by turning large adjustment screw (B) . One quarter turn of adjustment screw (B) changes the pressure setting by 1512 kPa (220 psi). 10. The LOW setting of the relief valve can be changed by turning small adjustment screw (C) . One quarter turn of adjustment screw (C) changes the pressure setting by 755 kPa (110 psi). 11. Both screws turn clockwise in order to increase the pressure setting and both screws turn counterclockwise in order to decrease the pressure setting.
I tried to follow the directions to the letter, but I didn't seem to get the expected results. Maybe I'm just a little simple. The locknut between A and B doesn't seem to lock anything. Nut B doesn't seem to adjust anything. The allen screw in the end adjusts the pressure. I did get the pressure to 3500 psi when the stroke ended on every function. However if there is a "low" pressure on this one I haven't found it. What would be the purpose of that 400 psi less, when exactly would you see it? From the procedure above it seems like only when boom up and roll back are both at the end of stroke. When I did that, I still got 3500. Also, if the outside locknut is missing, it would have to be mighty thin, there's only 3 threads showing without it.
Try running the lift arms up until the hoist cylinders top out. In that position put the hoist lever in Hold and then measure the pressure when you put the tilt control into the Tilt Back position. Put an Allen key in the end of the adjuster and back it out about half a turn while keeping everything else from moving. According to the procedure each quarter turn should change the pressure by 110psi so whatever you measured using Tilt Back previously should reduce by just over 200psi. Even if it doesn't, try backing it out another half a turn and see what happens. Just keep a close track on how much you have backed it out. I'm wondering at this point if the inner adjuster has been screwed so far in at some point in the past and has bottomed out. You may have to back it out a lot more than you imagine. I'd also suggest that every time you move the adjusting screw you should also measure the pressure you get when you put the hoist control in Raise. At some point the two pressures (using Hoist raise or Tilt back) should become different. I understand the "only 3 threads showing" but if you look at the illustration on the previous page the locknut is only very thin.
I turned the Allen screw while holding the other nuts and it changed the relief setting for every function. So I set it at 3400-3450. Before I changed the pump I removed the relief valve and disassembled it and found an aluminum shaving from under the B nut, so possibly that nut is stripped? If the pressure never goes over the 3500, am I going to hurt anything?
The testing and adjusting procedure will be for the dual-pressure system controlled by the solenoid which we established you don't have back on the first page. You should see the same pressure in lift and rack back. The low pressure setting is (was) to give a bit more horsepower to the tracks.
Any idea why the T&A says nothing about the later system Chris.?
Not sure. I thought there was a service letter detailing the change but a brief search right now can't find it. I'm in a hurry but might be able to get back to it later.
I've been pushing brush with the machine, seems to be working properly, going to put a few hours on it and change hydraulic filters again and check the pressure.