Hydraulic System Performance and Troubleshooting for the Bobcat 863 Skid Steer Loader

[MikePhua]

The Bobcat 863 and Its Role in Compact Construction
Introduced in the late 1990s, the Bobcat 863 was part of a generation of skid steer loaders that emphasized hydraulic power, operator comfort, and rugged versatility. Built by Bobcat Company, a division of Doosan Group, the 863 featured a Deutz BF4M1011 turbocharged diesel engine rated at 73.5 horsepower and a hydrostatic transmission. With a rated operating capacity of 1,900 to 2,000 lbs and a tipping load of 4,000 lbs, the 863 became a staple in landscaping, demolition, and utility work.
Thousands of units were sold across North America and Europe, and many remain in active service today. Its hydraulic system, while powerful, requires careful maintenance and understanding to ensure consistent performance.
Hydraulic System Specifications and Layout
The Bobcat 863 uses a closed-center hydraulic system driven by a gear-type pump. The system is designed to deliver high flow rates for lift, tilt, and auxiliary functions.
Key specifications:

• Hydraulic pump capacity: 18 gallons per minute (68 liters per minute)
  
• System relief pressure: 3,000 psi (206 bar)
  
• Hydraulic fluid type: Bobcat Hydraulic/Hydrostatic Fluid or ISO 46 equivalent
  
• Reservoir capacity: Approximately 10 gallons
  

The system powers:

• Loader lift and tilt cylinders
  
• Drive motors via hydrostatic transmission
  
• Auxiliary hydraulic ports for attachments
  
• Control valves and pilot circuits
  

The pump is mounted directly to the engine and supplies fluid to a series of control valves located beneath the operator seat. Each valve is actuated by mechanical linkages or solenoids, depending on the model variant.
Common Hydraulic Issues and Field Symptoms
Operators of the 863 often report hydraulic problems that manifest as sluggish movement, weak lifting, or erratic control response. These symptoms typically point to one or more of the following:

• Low hydraulic fluid level
  
• Contaminated or degraded fluid
  
• Clogged hydraulic filters or suction lines
  
• Air trapped in the system
  
• Faulty relief valve or misadjusted pressure settings
  
• Worn or damaged hydraulic pump
  
• Malfunctioning control valves or solenoids
  
• Leaking or damaged hydraulic cylinders
  

A contractor in Alberta shared how his 863 began losing lift power during cold mornings. After checking fluid levels and replacing the hydraulic filter, he discovered that the suction line had collapsed internally due to age. Replacing the line restored full function.
Auxiliary Hydraulic Circuit and Attachment Control
The 863 includes auxiliary hydraulic ports for powering attachments such as augers, grapples, and trenchers. These are controlled via switches on the joystick or dash panel, depending on the series (C, F, or G).
Troubleshooting auxiliary flow issues:

• Verify power to solenoids and switches
  
• Check for magnetic pull on coil actuators
  
• Inspect spool valves for sticking or wear
  
• Confirm that the auxiliary control module is functioning
  
• Test flow rate and pressure at the couplers
  

In high-flow models, auxiliary output can exceed 30 GPM. If attachments fail to respond, the issue may lie in the control circuit or a blocked valve. A technician in Georgia rebuilt his auxiliary valve after discovering debris from a ruptured hose had lodged in the spool bore.
Preventive Maintenance and Service Intervals
To maintain hydraulic performance, follow these service guidelines:

• Check fluid level daily before operation
  
• Change hydraulic fluid every 1,000 hours or annually
  
• Replace filters every 500 hours or when pressure drops
  
• Inspect hoses and fittings monthly for leaks or abrasion
  
• Bleed air from the system after any major repair
  
• Monitor system pressure during operation using diagnostic ports
  

Use only approved hydraulic fluid to avoid seal degradation and pump wear. Avoid mixing fluid types, and flush the system thoroughly when switching brands or viscosity grades.
Upgrades and Retrofit Possibilities
Owners of older 863 units often retrofit components to improve reliability:

• Install inline pressure gauges for real-time monitoring
  
• Upgrade to spin-on filter housings for easier service
  
• Replace mechanical linkages with pilot-operated joystick controls
  
• Add quick-connect couplers with dust caps to protect auxiliary ports
  

Some operators also install external coolers to manage hydraulic temperature during summer operations or high-duty cycles.
Conclusion
The hydraulic system of the Bobcat 863 is the heart of its performance, powering everything from lift arms to attachments. Understanding its layout, maintaining fluid integrity, and diagnosing pressure-related issues are essential for keeping the machine productive. With proper care and a proactive approach, the 863 continues to deliver reliable service in the field—proof that compact power and smart hydraulics can stand the test of time.