I've got 953c 2zn742 track loader and today all of a sudden the lift arm started going up very slowly today . Fluid was a little low, so filled it up and no change. Run it a little while longer and looked at the fluid again and seem to be a little bubbly at the top. Anybody no what's the problem? Relief valves , seals , orings in the tank?:Banghead
It could be a number of things; Do the lift cyls drift? If so, possible piston seal or line relief valve trouble. Any abnormal noise? If so, possible pump cartridge failure. Is the tilt also affected? If so, possible main relief trouble. In my experience, it is most likely to be one of the second two. The next troubleshooting step would be to check the main relief pressure. The pressure tap is under the front cover near the hydraulic tank sight glass.
No noise. Pump was replaced 9 months ago. Tilt is not effected, it works normal. What shoul the pressures be on the ports.
2zn0742 Ss#
What do you mean when you say drift?
When you lift the arms and return the lever to neutral, do the arms drop under their own weight? The main relief pressure is 3500psi, give or take a little.
I worked for a guy that had a 953 that did that after the pump was replaced. The boom raised up under its own power, didn't stop till the machine was shut down. A piece of metal from the old pump got into the hydraulics and worked its way all the way to the valve for the lift cylinders. Opened them wide open with no control. Just my 2 cents worth with something similar
Had a pump doing that. Put a gauge on it and see what you got. Also Liston to the pump with a stethoscope for noise
Put a gauge on it today and the pressure wouldn't go above 700psi. The pressure is supposed to be around 3000 give or take a few. I think it's a relief valve in the tank but how do I know which one. There's 2 small ones and 1 larger one. Any body know ? Thanks for all the info.
700psi on just the lift or on all functions?
There's is two ports near the sight glass. On directly below th sight glass, which I got know reading from what so ever. The other one is lower on a square aluminum block with 4 bolts . Got a reading of no more than 700psi. ANY THOUGHTS? Thanks
Just the lift. Didn't try tilt
Before you go diving into the line relief valves in the hydraulic tank you need to confirm if you have low pressure both up/down and tip/crowd because it could be a main relief problem and that isn't in the tank. (Also check 4 in 1 and/or rippers is fitted) The test port reading no pressure will be for tank pressure. You are correct testing it at the test point on the block.
Ok I'll check tilt tomorrow. If it's low on both lift and tilt then it's the main relief?
Yes, or pump.
Where is the main relief located?
Where is the main relief located?
Where's the main relief valve? Sorry if this posted more than once. Something went wrong
It's in the block where the test port is. There may or may not be a solenoid valve alongside it. If you do suspect the MPRV, remove it by unscrewing the largest hex next to the block and check the O rings. Next, look up the hole in the end. It's not unknown for them to get debris stuck under the seat. Depending on which one you have, you might be able to dismantle and clean it, but mark the adjusting screw or count the number of turns or something so you assemble it the same. If you're unlucky, you'll find you have a sealed, non repairable type and then you'll have to buy a new one.
Ok thanks for the help. Let you know how it goes
Ruled out the pump being bad today. I think it's the lift relief valve in the tank. Will have to take tank out to get to it sounds like a real fun job. Not looking forward to it but has to be done. Anybody know off hand which valve it is. There's two next to each other. I guess I can just trace it by the lift arm hydraulic lines
If you want the Test & Adjust procedure for the complete hydraulic system drop me a PM with your email address.