Restoring Continuous Hydraulic Flow on the Bobcat 753C Loader

[MikePhua]

The Bobcat 753C and Its Hydraulic Architecture
The Bobcat 753C skid steer loader was introduced in the late 1990s as part of Bobcat’s compact equipment evolution. With a rated operating capacity of 1,500 pounds and a 43-horsepower Kubota diesel engine, the 753C was designed for versatility in landscaping, construction, and agricultural tasks. Bobcat, founded in 1947, had already become a global leader in compact loaders, and the 753C continued that legacy with a robust hydraulic system and reliable auxiliary circuits.
The 753C features an open-center hydraulic system with gear-type pumps and a manually activated auxiliary flow circuit. This system powers lift arms, bucket tilt, and attachments such as augers, trenchers, and sweepers. Continuous flow is essential for running hydraulic tools that require uninterrupted pressure, and when that function fails, productivity suffers.
Terminology Notes

• Auxiliary Hydraulics: A secondary hydraulic circuit used to power external attachments
  
• Continuous Flow: A mode where hydraulic fluid flows uninterrupted to an attachment without holding the control lever
  
• Detent: A mechanical or hydraulic latch that holds a valve in the open position
  
• Solenoid Valve: An electrically actuated valve that controls fluid flow based on switch input
  
• Toggle Switch: A manual switch used to activate auxiliary hydraulic functions
  

Symptoms of Lost Continuous Flow
Operators may encounter several signs when continuous flow fails:

• Attachment stops running when the control lever is released
  
• No response from the auxiliary circuit despite switch activation
  
• Intermittent flow that cuts in and out under load
  
• Audible clicking from solenoids but no hydraulic movement
  
• Attachments work only when the lever is manually held
  

In 2012, a contractor in Alberta reported that his 753C would not maintain flow to a hydraulic broom. After inspecting the toggle switch and solenoid wiring, he discovered a broken ground wire behind the seat. Reconnecting the wire restored full continuous flow.
Root Causes and Diagnostic Pathways
Several components can interrupt continuous flow:

• Faulty Toggle Switch or Wiring
  The switch sends an electrical signal to the solenoid valve. If the switch fails or wiring is damaged, the valve won’t engage.
  
• Stuck or Worn Detent Mechanism
  The detent holds the valve open for continuous flow. Dirt, corrosion, or wear can prevent it from locking in place.
  
• Solenoid Valve Failure
  A burned coil or stuck spool inside the solenoid can block flow. Test voltage at the coil and inspect for magnetism when energized.
  
• Hydraulic Contamination
  Debris in the fluid can clog valve passages or restrict spool movement. Flush the system and replace filters.
  
• Incorrect Attachment Setup
  Some attachments require specific flow rates or pressure settings. Verify compatibility and check quick coupler connections.
  

Inspection and Repair Steps
To restore continuous flow:

• Park the machine and disconnect the battery
  
• Remove the right-side panel to access the toggle switch and wiring
  
• Test switch continuity with a multimeter
  
• Inspect solenoid coil resistance and verify voltage during activation
  
• Clean or replace the detent mechanism on the auxiliary valve
  
• Flush hydraulic fluid and replace filters if contamination is suspected
  
• Test the system with a known working attachment
  

Use dielectric grease on connectors and secure all grounds to prevent future electrical faults. If the solenoid coil is weak, replace it with an OEM-rated component.
Preventative Maintenance and Operator Tips
To keep auxiliary hydraulics functioning:

• Test continuous flow monthly with a hydraulic tool
  
• Inspect toggle switch and wiring quarterly
  
• Clean quick couplers before each attachment change
  
• Replace hydraulic filters every 500 hours
  
• Use manufacturer-approved fluid and monitor for discoloration or odor
  
• Train operators to engage continuous flow properly and avoid forcing the detent
  

For machines operating in wet or dusty environments, consider installing sealed switches and protective boots over connectors.
Modern Comparisons and System Evolution
Newer Bobcat models like the S590 and T66 feature electronically controlled auxiliary circuits with touchscreen activation and programmable flow rates. These systems offer better precision and diagnostics but require dealer-level tools for troubleshooting.
The 753C, while mechanically simpler, remains a favorite among independent operators and rental fleets. Its auxiliary system can be serviced in the field with basic tools, and parts are widely available through aftermarket suppliers.
Conclusion
Loss of continuous hydraulic flow on the Bobcat 753C is often caused by electrical faults, detent wear, or solenoid failure. By methodically inspecting the switch, wiring, and valve components, operators can restore full functionality and keep attachments running smoothly. In compact loader work, uninterrupted flow means uninterrupted progress—and the fix is often closer than it seems.