John Deere Technical Notes
Loader and backhoe boom/bucket lower slowly while parked
Symptoms
What is normal leak down for the Selective Control Valve (SCV)?
Situation or Problem
No publication specifies a procedure or allowable specification.
Summary
Step One
Place the backhoe or loader boom cylinder in the half-extended position with bucket empty.
Step Two
Measure the amount of rod extending from the cylinder.
Step Three
Allow the implement to sit undisturbed for 30 minutes.
Step Four
Measure the amount of rod that extends from the cylinder again.
Step Five
If the rod movement exceeds the maximum allowable travel listed in the charts below, determine if the SCV or the cylinder is leaking excessively by:
Stroke the valve to extend the cylinder to full stroke.
CAUTION: To avoid possible injury, support the implement before hose removal. Unexpected movement of the implement could occur and result in serious injury, if the wrong hose is disconnected. Make sure the return line is the one being removed. This is the line at the cylinder's rod end when the cylinder is extended. Avoid oil penetration injury when observing for cylinder leakage.
Remove the return hose from the cylinder.
Stroke the valve in the extend direction again.
If oil comes out of the disconnected cylinder fitting, the cylinder is leaking.
If oil does not come out of the disconnected cylinder fitting, the valve is leaking.
Maximum Allowable Travel 410 Loader Lift cylinder, 191 mm (7.5 in.) / hour
410 Loader Bucket cylinder, 313 mm (12.3 in.) / hour
420 Loader Lift cylinder, 150 mm (5.9 in.) / hour
420 Loader Bucket cylinder, 218 mm (8.6 in.) / hour
430 Loader Lift cylinder, 117 mm (4.6 in.) / hour
430 Loader Bucket cylinder, 219 mm (8.6 in.) / hour
440 Loader Lift cylinder, 150 mm (5.9 in.) / hour
440 Loader Bucket cylinder, 218 mm (8.6 in.) / hour
460 Loader Lift cylinder, 965 mm (3.8 in.) / hour
460 Loader Bucket cylinder, 145 mm (5.7 in.) / hour
47 Backhoe Lift cylinder, 15 mm (0.6 in.) / minute
47 Backhoe Stabilizer cylinder, 8 mm (0.3 in.) / minute
47 Backhoe Stabilizer cylinder (retract rate), 5 mm (0.2 in.) / minute
48 Backhoe Lift cylinder, 10 mm (0.4 in.) / minute
48 Backhoe Stabilizer cylinder, 5 mm (0.2 in.) / minute
48 Backhoe Stabilizer cylinder (retract rate), 5 mm (0.2 in.) / minute
Additional Information
When disconnecting the return hose from the cylinder to determine leakage of the cylinder or SCV on a loader, both cylinders' returns are tied together. If leakage is observed from the disconnected cylinder, that cylinder is leaking. If leakage is observed from the hose, the opposite cylinder is leaking.
Affected Equipment Model: 790
Model: 990
Model: 4100
Model: 4200
Model: 4300
Model: 4400
Model: 4500
Model: 4600
Model: 4700
Model: 410 Loader
Model: 420 Loader
Model: 430 Loader
Model: 440 Loader
Model: 47 Backhoe
Model: 48 Backhoe
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