Hydraulic Shutdown After Warm-Up on the ASV RC-50

[MikePhua]

The ASV RC-50 and Its Hydraulic System Design
The ASV RC-50 compact track loader was introduced in the early 2000s as part of ASV’s push into the mid-size skid steer market. Known for its rubber track undercarriage and smooth ride over rough terrain, the RC-50 was designed for landscaping, light construction, and utility work. With a 50-horsepower Perkins diesel engine and a hydraulic system delivering up to 15 gpm, it offered solid performance in a compact footprint.
ASV, founded in Minnesota in 1983, built its reputation on suspended undercarriages and low ground pressure machines. The RC-50’s hydraulic system powers both the drive motors and auxiliary functions, including attachments like augers, trenchers, and brush cutters. It uses a gear pump and pilot-controlled valves, with electrical relays and safety switches integrated into the control logic.
Symptoms of Hydraulic Cutoff After 10 Minutes
A recurring issue reported by operators is the sudden loss of hydraulic function after approximately 10 minutes of operation. This includes:

• Drive motors losing power or locking up
  
• Auxiliary hydraulics cutting out completely
  
• Machine behaving as if the parking brake has engaged
  
• No warning lights or fault codes displayed
  
• Restarting the machine temporarily restores function
  

Terminology notes:

• Pilot pressure: Low-pressure hydraulic signal used to control high-pressure valves.
  
• Safety solenoid: An electrically actuated valve that disables hydraulic flow when triggered by safety circuits.
  

In Ontario, a contractor experienced this issue after rebuilding the hydraulic pump. The machine ran smoothly for a few minutes, then abruptly lost drive and auxiliary power. Restarting restored function, but the problem repeated consistently.
Electrical and Safety Circuit Considerations
The RC-50 integrates several safety features that can interrupt hydraulic flow:

• Seat switch detecting operator presence
  
• Overhead lever safety switch
  
• Auxiliary hydraulic switch on the panel
  
• Safety relay controlling the hydraulic enable solenoid
  
• Fuse panel and main relay connections
  

Common failure points include:

• Corroded or loose connectors at the fuse panel
  
• Worn or misaligned seat switch
  
• Deformed relay sockets causing intermittent contact
  
• Grounding issues leading to voltage drop
  
• Damaged wiring under the cab or near the valve block
  

Diagnostic steps:

• Inspect all safety switches for continuity and proper actuation
  
• Test voltage at the hydraulic solenoid during operation
  
• Check relay sockets for heat damage or loose pins
  
• Bypass seat switch temporarily to isolate fault
  
• Clean and reseat all fuses and relays
  

In Florida, a grading crew resolved the issue by replacing a deformed relay socket and installing an external relay with jumper wires. This restored consistent hydraulic function.
Hydraulic System Heat and Pressure Effects
Another possibility is thermal expansion or pressure loss in the hydraulic system:

• Hydraulic fluid thinning as temperature rises
  
• Internal leakage in pump or valve block
  
• Pressure relief valve sticking or misadjusted
  
• Case drain restriction causing backpressure
  
• Air entrainment from recent service or fluid change
  

Recommended checks:

• Monitor hydraulic fluid temperature with infrared thermometer
  
• Inspect return lines and case drain for flow restriction
  
• Test pilot pressure at valve block after warm-up
  
• Replace hydraulic filter and check for contamination
  
• Bleed air from system by cycling functions at low RPM
  

In Chile, a forestry crew added a hydraulic cooler to their RC-50 after repeated shutdowns in hot weather. The cooler reduced fluid temperature by 15°C and eliminated the issue.
Drive Motor and Control Valve Behavior
If the drive motors lock up while auxiliary hydraulics also fail, the issue likely involves:

• Loss of pilot pressure due to solenoid failure
  
• Electrical interruption to valve control circuit
  
• Internal valve sticking from contamination
  
• ECM or control module glitch (if equipped)
  

Suggested actions:

• Remove and clean hydraulic solenoids
  
• Replace pilot valve seals and check spool movement
  
• Inspect wiring harness for wear or rodent damage
  
• Test drive motor case drain flow for signs of internal leakage
  
• Replace hydraulic fluid with OEM-rated oil and monitor performance
  

In Tennessee, a contractor found a damaged wire near the pilot valve that intermittently grounded out. After repairing the harness, the machine ran without interruption.
Preventive Maintenance and Long-Term Solutions
To prevent hydraulic shutdowns:

• Inspect electrical connectors monthly
  
• Replace safety switches every 1,000 hours or at signs of wear
  
• Flush hydraulic system annually and replace filters
  
• Keep fuse panel dry and protected from vibration
  
• Log shutdown events and correlate with temperature or terrain
  

Suggested upgrades:

• Install external relay block with sealed connectors
  
• Add hydraulic temperature sensor to monitor fluid heat
  
• Use synthetic hydraulic fluid for better thermal stability
  
• Retrofit seat switch with magnetic sensor for reliability
  

In South Africa, a vineyard crew added a diagnostic LED to their hydraulic solenoid circuit. When the light went out, they knew instantly that the safety circuit had disengaged.
Parts Availability and Sourcing Tips
RC-50 components are available through:

• ASV dealers and service centers
  
• Aftermarket suppliers offering electrical and hydraulic parts
  
• Salvage yards with compatible RC-series inventory
  
• Electronics shops for relay and switch replacements
  

Sourcing advice:

• Match solenoid and relay part numbers carefully
  
• Use marine-grade wire and sealed connectors for repairs
  
• Replace hydraulic filters with OEM-rated elements
  
• Document all wiring changes for future troubleshooting
  

In New Zealand, a contractor rebuilt his RC-50’s electrical system using upgraded wiring and waterproof relays. After 1,500 hours, the machine remained fault-free.
Operator Stories and Field Wisdom
In Poland, a snow-clearing team used an RC-50 with intermittent hydraulic loss. After bypassing the seat switch and replacing the fuse panel, the issue disappeared.
In Alberta, a contractor added a manual override switch to the hydraulic enable solenoid. This allowed emergency operation during diagnostics and reduced downtime.
Conclusion
Hydraulic shutdown after warm-up on the ASV RC-50 is often a blend of electrical and thermal factors. Whether caused by a faulty safety switch, corroded relay, or fluid overheating, the issue can be resolved with methodical diagnostics and targeted upgrades. In the field, hydraulic reliability is everything—and keeping the system clean, cool, and connected ensures the RC-50 performs as it was built to.