Hi guys, I have a customer what a 2008 CAT 962H on 14K hours, we have no lift and very minimal moment on the bucket tilt forward or back. Anyone have any pointers? We checked pilot pressure but it doesn’t sense the pump loading so only reading 100psi
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CAT 962H poor hydraulics
- Thread starter wee_gus
- Start date
Nige
Senior Member
S/No.?
Any Diagnostic Codes.?
How did the problem start. Did it get worse over time or has the problem come up suddenly.? If it still has the original pump at 14k and if it has slowly got worse over time the pump (and maybe more components in the hydraulic system) are probably worn out.
Has anyone tried calibrating the controls and the proportional solenoid valves.? (It needs ET to do it.)
Any Diagnostic Codes.?
How did the problem start. Did it get worse over time or has the problem come up suddenly.? If it still has the original pump at 14k and if it has slowly got worse over time the pump (and maybe more components in the hydraulic system) are probably worn out.
Has anyone tried calibrating the controls and the proportional solenoid valves.? (It needs ET to do it.)
S/N N4A 1071
Year 2008
No diagnostic codes present.
I believe from what I’ve been told it was parked up one evening ok next day the loader wouldn’t lift and would only tilt forward and backwards 2-4” then nothing.
no I don’t believe they have tried to calibrate the controls
Year 2008
No diagnostic codes present.
I believe from what I’ve been told it was parked up one evening ok next day the loader wouldn’t lift and would only tilt forward and backwards 2-4” then nothing.
no I don’t believe they have tried to calibrate the controls
Nige
Senior Member
Hmm. That could be true but smells fishy to me. But if you weren't there you can't say it's not true.
I'd have a bash at calibrating both the controls and the proportional solenoids for the main control valve.
After that it's get the pressure gauges out on the pump side. Has it lost the pilot side of the implement pump.?
Attached the hydraulic schematic.
Simon C
Senior Member
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- Rocky Mountain House , AB., Canada
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- Heavy Equipment Mechanic
Seen a 980H same vintage that I parked in front of shop to change oil. No more bucket after start up. Was a bad solenoid all rusted up under front boom cover plate. Had to get new one and all was well after that. Simon
Simon C
Senior Member
- Joined
- Jul 1, 2015
- Messages
- 676
- Location
- Rocky Mountain House , AB., Canada
- Occupation
- Heavy Equipment Mechanic
Also seen a 980H with 8500 Hrs have hydraulic pump crater suddenly one day. Cab off Job to do them. Simon
Per Eriksson
Senior Member
You may have a pump issue, the standby pressure should normally be well above 100psi, spec is 305psi so if the pilot pressure reducing valve is ok you'd have the same reading on the pilot tap also.
put a gauge on main pump pressur test port and verify if you get the same low reading as the pilot pressure tap.
If you are lucky it might be a bad pilot pressure reducing valve or pilot shutoff solenoid but they usually fail completely when they go bad.
put a gauge on main pump pressur test port and verify if you get the same low reading as the pilot pressure tap.
If you are lucky it might be a bad pilot pressure reducing valve or pilot shutoff solenoid but they usually fail completely when they go bad.
Ok so a little update, got machine back to shop, pulled valves from chest and found some contamination asking with weak springs on the spools for the ride control we have replaced both of these and it did somewhat improve the hydraulics but still not enough to lift the loader frame, we do have more tilt function but still not 100%
Nige
Senior Member
Did you manage to calibrate the control lever position sensors and the proportional solenoids for the lift & tilt circuits.?
Not as yet but we shall be doing so on Monday once our CAT ET arrives
Nige
Senior Member
I would suggest calibrations in the following order:-
Control lever position sensors.
Linkage position sensors.
Proportional solenoid valves. (From memory for this one the implement hydraulic oil temperature needs to be above something like 65C or it will abort)
Control lever position sensors.
Linkage position sensors.
Proportional solenoid valves. (From memory for this one the implement hydraulic oil temperature needs to be above something like 65C or it will abort)
attempeted to do the calibrations today, only could do the levers as we can’t raise the loader frame.
When you operate the loader function you can hear the pump upstroke and up Rev the engine slightly and the lift will move approx 1”
Tilt on the other hand will move approx 4” before it stops working.
I’m thinking a valve issue.
Per Eriksson
Senior Member
Ok, back to the basics,
What do you read on pilot pressure tap?
Implement pump pressure tap at low and high idle standby?
Same when attempting a lift or tilt move?
What do you read on pilot pressure tap?
Implement pump pressure tap at low and high idle standby?
Same when attempting a lift or tilt move?
From memory was 500-550 psi for pilot l.
can’t dead head the service to get a proper reading but when operating the service and when it moves it goes to around 1000 psi and drops to zero
Per Eriksson
Senior Member
So, assuming the pump is ok and having good standby pressure of atleast 300psi which I think it does since you got the correct pilot pressure you should look at the load sense relief valve, located left rear of valvebody.
There's a new version that has a round body with hex shape only on the end that's supposed to be more reliable.
Then there's the load sense duplication valve located just below the ls relief valve, check the seals on that one.
If these looks ok and moves freely the next thing to check is the margin relief valve located front and center of the valve body.
There's a new version that has a round body with hex shape only on the end that's supposed to be more reliable.
Then there's the load sense duplication valve located just below the ls relief valve, check the seals on that one.
If these looks ok and moves freely the next thing to check is the margin relief valve located front and center of the valve body.
jesusquijadag
New Member
Hi, I'm 2 years late but I'm having the same problem with a 962H prefix SSA, the machine was parked for a long time and now it starts but only moves the tilt, it doesn't move the lift cylinders at all.
I would like to know if this problem was solved as I see it is very similar. Adding that when I increase the engine rpm the machine lowers the implement by itself but there is no way to lower it using the joystick.
I would like to know if this problem was solved as I see it is very similar. Adding that when I increase the engine rpm the machine lowers the implement by itself but there is no way to lower it using the joystick.