JOHN DEERE 490E ,690E, HITACHI 120,200 CROWD BOOM (STICK) PROBLEMS

[Dwallace]

I have a john deere 490E the machine runs and functions good except for the stick in and out. if you bounce or surge it she'll take off and move. or a load of dirt already extended out a little. it'll go when activated. also digging if there pressure against boom she'll drag the machine. but if you let it hang limp no load she'll barely move unless you curl same time then she'll move half ass. I,ve cleaned all hydraulic filters including in the tank new oil. I,ve tested pilot pressure by adding tee at the caps. this (stic)k spool has about 500-550psi while activating the fucntion. all the other spools have 850-900 while activating.
so I swapped some control lines. the problem stayed in that (stick) spool. Now i'm wondering if there are orings under that cap. or if I should be looking at the porportional control valve. or maybe somewhere else. i'm sure some one has had this same issue with this machine.

 

[mg2361]

A bounce or surge to get it to move normally I would suspect and stuck load sense poppet, variable compensator or other valve or an electrical issue intermittently making a connection. Maybe an issue with the combined function caused by a pressure switch causing the PVC to think the machine requires combined flow so it is limiting the arm movement. So many possibilities. These machines are frustrating at best.

I would suggest looking in the Operation and Test manual TM1504 section 9025-15 and look for "Introduction to Flow Charts". In the first chart there is a section labeled one function slow and gives you a list of possibilities that could cause that issue. Have all those "possibilities" been eliminated?

 

[Dwallace]

where on valve bank is the load sense poppet and variable compensator? and yes by swapping pilot control lines at the caps I eliminated pressure switches computer issues and all other valves. because when I swapped lines the stick function operated the main boom perfectly. and the main boom function had same problem with stick.
i figured a new post might be better than on an old one.

 

[LACHAU]

so I swapped some control lines. the problem stayed in that (stick) spool.

when I swapped lines the stick function operated the main boom perfectly. and the main boom function had same problem with stick.

You mean:
1. swap control lines ==> no change.
2. Swap main lines BOOM <---> ARM (STICK)==> It changes, ARM function's OK but BOOM function get problem??

 

[Dwallace]

no sir, when I swapped control lines at caps. problem stayed in the arm (stick)

 

[Dwallace]

it acts the same in both directions. in and out. so i'm thinking variable compensation valve. not sure but I think it's the sqaure plate behind steel line that comes from solenoid. looks like purdy major job to access so trying to identify before jumping in.

 

[mg2361]

The rectangular plates that sit horizontally between the lines that go to the cylinders are where the compensators are located.

@LACHAU , he swapped the pilot lines on the control valve between the boom and the arm.

 

[LACHAU]

@LACHAU , he swapped the pilot lines on the control valve between the boom and the arm.

it acts the same in both directions. in and out. so i'm thinking variable compensation valve. not sure but I think it's the square plate behind steel line that comes from solenoid. looks like purdy major job to access so trying to identify before jumping in.

All right, the first thing to do because it's easy is "combine operations", eg. ARM IN (OUT) + BUCKET DUMP (DIG).
If ARM's operations is normal when "COMBINED OPERATION"......We should check the "SHUTTLE VALVE" in Main control valve.

 

[LACHAU]

The second way for checking:
1. Measure DP (Difference Pressure) sensor Voltage ===> It should be changed when ARM IN (or OUT) operation.
2. If you have Dr.EX (ZX), check as below image.

 

[Dwallace]

I have done the back probe test on dp sensor got the voltage drop on all functions except for the (stick) very little drop while hanging limp and activating. but as it came against resistance it dropped as pressure rose.
stick will move if you use curl at same time. not great but will move.

shuttle valves are behind mounting plate that holds whole main valve in. no way too access those plugs.
is there a procedure to get at them other than remove whole valve? even if I take 4 bolts out I don't think steel lines would allow valve to move forward.
could it be the solenoid feeding variable compensation valve? I,ve got 24v can't tell if it's operating or not. I think ecm gives it the ground.
thinking about teeing in with test gauge. or dead head into gauge? or crack it loose see if it sprays?

 

[LACHAU]

I have done the back probe test on dp sensor got the voltage drop on all functions except for the (stick) very little drop while hanging limp and activating. but as it came against resistance it dropped as pressure rose.
stick will move if you use curl at same time. not great but will move.

shuttle valves are behind mounting plate that holds whole main valve in. no way too access those plugs.
is there a procedure to get at them other than remove whole valve? even if I take 4 bolts out I don't think steel lines would allow valve to move forward.
could it be the solenoid feeding variable compensation valve? I,ve got 24v can't tell if it's operating or not. I think ecm gives it the ground.
thinking about teeing in with test gauge. or dead head into gauge? or crack it loose see if it sprays?

1. "..could it be the solenoid feeding variable compensation valve?"
It's OK, you can check them, It's very easy for testing.
PSV ON ===> Hydraulic line ON (get secondary pilot pressure).
PSV OFF ===> Hydraulic line OFF (get tank pressure). You can check by holding it with your hands.
When STICK operate ===> PSV for STICK must be OFF.

2. "...I,ve got 24v can't tell if it's operating or not".
OMG!!! That work can broken out PSV!! The PSV 's controlled by PWM (Pulse Width Modulation). You should connect a resistor in series.

 

[Dwallace]

what is psv?
basically your saying hold the solenoid. feel it click when cycle the stick?
OMG!!! That work can broken out PSV!!

 

[LACHAU]

what is psv?
basically your saying hold the solenoid. feel it click when cycle the stick?
OMG!!! That work can broken out PSV!!

I remember that I already have been talking about PSV = Proportional Solenoid Valve.
Those PSV control Variable Pressure Compensated Valve as image which I just post above.

 

[Dwallace]

mg2361 what is he suggesting I do to test if solenoid is working?
can this be the problem?

1. "..could it be the solenoid feeding variable compensation valve?"
It's OK, you can check them, It's very easy for testing.
PSV ON ===> Hydraulic line ON (get secondary pilot pressure).
PSV OFF ===> Hydraulic line OFF (get tank pressure). You can check by holding it with your hands.
When STICK operate ===> PSV for STICK must be OFF.

2. "...I,ve got 24v can't tell if it's operating or not".
OMG!!! That work can broken out PSV!! The PSV 's controlled by PWM (Pulse Width Modulation). You should connect a resistor in series.

 

[mg2361]

Let's start over. Does the arm work normally in combined operation as in arm out bucket dump, arm in bucket curl or when any other function is activated while using the "limpy" arm? How about if you have your "limpy" arm then stall the bucket function at the same time? If it improves when another function is activated that tells me the load sense pressure is not getting to where it needs to go from the arm circuit. When another function is activated you create load sense and the pump comes into stroke and when that happens the arm moves faster. Post #8 has a graphic that would apply to this scenario.

 

[Dwallace]

yes it does move better when any other function is in use same time. the shuttle valve to that spool is behind the mount bracket. looks like whole valve would have to be removed. that's a major deal.
am I incorrect thinking that the solenoid supplies the variable pressure compensation valve with oil. which causes pump to stroke? via a ground signal from ecm(computer)
are there o rings behind that plate? that could cause this issue.(variable pressure compensation )
I do appreciate all the help guy's!!
i'm trying to narrow down to a specific fix before diving into valve. I have a limited amount of time to work on the ole hoe.

 

[Tones]

The UH series had a flow control for the dipper which could be ajusted and was mounted on the boom. I can't remember if the EX series had the same setup but it would pay to have a look. It was real easy to adjust

 

[Dwallace]

lines from valve go straight to cylinders

 

[mg2361]

am I incorrect thinking that the solenoid supplies the variable pressure compensation valve with oil. which causes pump to stroke?

Not quite. The solenoid helps control functions in a multifunction operation. It should not be doing anything if just working the arm. Tee into the line for the arm proportional solenoid valve with a pressure gauge (1000 psi gauge) and operate the arm function (Work mode "M" - General Purpose, Power mode in "P", auto idle off). What pressure do you have arm in and arm out? Then also record the pressure for each function one at a time, swing, boom raise, boom lower, bucket curl and dump and post results. Record the numbers again in Precision mode as well. This will tells me if the solenoid is the issue or not.

 

[mg2361]

Post pressure with controls in neutral as well.