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The Bobcat 873 and Its Cooling System
The Bobcat 873 skid-steer loader was introduced in the late 1990s as part of Bobcat’s G-series, designed to offer higher horsepower and hydraulic performance for demanding tasks. Powered by a Deutz BF4M1011F oil-cooled diesel engine, the 873 featured a vertical lift path, a rated operating capacity of 2,200 lbs, and a hydraulic flow of up to 20.6 gallons per minute. It quickly became a popular choice for contractors, landscapers, and municipalities due to its compact size and robust lifting capability.
Bobcat Company, originally founded as Melroe Manufacturing in 1947, had by the early 2000s sold hundreds of thousands of skid-steers globally. The 873 was a mid-range model that bridged the gap between compact maneuverability and industrial-grade power.
Unlike most skid-steers that rely on liquid coolant and radiators, the 873’s Deutz engine uses oil for both lubrication and cooling. This design simplifies the system but requires meticulous maintenance to prevent overheating.
Common Symptoms of Overheating
Operators often report the following signs:
Terminology Notes
Several factors can contribute to overheating in the Bobcat 873:
In Arizona, a contractor named Luis noticed his 873 shutting down during trenching work. “We cleaned the exterior fins daily, but it kept overheating. Turned out the tensioner arm was frozen. Once we freed it and replaced the belt, it ran cool all day.”
A forestry crew in Oregon shared a story of flushing the oil cooler with kerosene after repeated shutdowns. “We thought the cooler was clean, but inside it was gummed up. After flushing and replacing the oil, the problem vanished.”
These stories highlight the importance of both external and internal maintenance.
Diagnostic Strategies
To pinpoint overheating causes:
To avoid overheating:
While the 873 is no longer in production, owners can enhance cooling performance with:
In 2024, a small engineering firm in Minnesota began offering retrofit kits for legacy Bobcat models, including the 873. These kits include upgraded oil coolers, tensioners, and digital monitoring systems. Field tests showed a 30% reduction in overheating incidents.
Meanwhile, a vocational school in Texas added the 873 to its training fleet, using it to teach students about oil-cooled engine systems and thermal diagnostics.
Conclusion
Overheating in the Bobcat 873 is a manageable issue when approached with methodical diagnostics and preventive care. Its oil-cooled Deutz engine offers simplicity and reliability, but demands attention to airflow, belt tension, and internal cleanliness. With proper maintenance and thoughtful upgrades, the 873 can continue to perform reliably in even the harshest conditions—proving that smart design and operator diligence go hand in hand.
The Bobcat 873 skid-steer loader was introduced in the late 1990s as part of Bobcat’s G-series, designed to offer higher horsepower and hydraulic performance for demanding tasks. Powered by a Deutz BF4M1011F oil-cooled diesel engine, the 873 featured a vertical lift path, a rated operating capacity of 2,200 lbs, and a hydraulic flow of up to 20.6 gallons per minute. It quickly became a popular choice for contractors, landscapers, and municipalities due to its compact size and robust lifting capability.
Bobcat Company, originally founded as Melroe Manufacturing in 1947, had by the early 2000s sold hundreds of thousands of skid-steers globally. The 873 was a mid-range model that bridged the gap between compact maneuverability and industrial-grade power.
Unlike most skid-steers that rely on liquid coolant and radiators, the 873’s Deutz engine uses oil for both lubrication and cooling. This design simplifies the system but requires meticulous maintenance to prevent overheating.
Common Symptoms of Overheating
Operators often report the following signs:
- Engine shuts down after 10–20 minutes of operation
- Warning lights or audible alarms
- Hot oil smell or visible vapor
- Reduced hydraulic performance
- Fan belt slippage or noise
Terminology Notes
- Oil-Cooled Engine: An engine that uses circulating oil to absorb and dissipate heat, replacing traditional coolant systems.
- Hydraulic Oil Cooler: A heat exchanger that cools hydraulic fluid before it returns to the reservoir.
- Fan Belt: A belt that drives the cooling fan and sometimes the oil pump, critical for airflow and circulation.
- Tensioner Arm: A spring-loaded or pivoting arm that maintains proper belt tension.
Several factors can contribute to overheating in the Bobcat 873:
- Clogged Oil Cooler Fins
Dust, mulch, and debris can block airflow through the cooler. This is especially common in landscaping and demolition work.
- Stuck Tensioner Arm
Corrosion or wear can cause the tensioner to seize, leading to a loose fan belt and reduced airflow.
- Worn or Slipping Fan Belt
A frayed or stretched belt may not spin the fan at full speed, compromising cooling.
- Internal Blockage in Oil Cooler
Sludge or varnish buildup inside the cooler can restrict oil flow, reducing heat transfer.
- Faulty Thermostat or Oil Pump
If oil circulation is impaired, heat accumulates rapidly. A stuck thermostat or weak pump can be the culprit.
- Overloading the Machine
Continuous operation at full hydraulic load can exceed the cooling system’s capacity, especially in high ambient temperatures.
In Arizona, a contractor named Luis noticed his 873 shutting down during trenching work. “We cleaned the exterior fins daily, but it kept overheating. Turned out the tensioner arm was frozen. Once we freed it and replaced the belt, it ran cool all day.”
A forestry crew in Oregon shared a story of flushing the oil cooler with kerosene after repeated shutdowns. “We thought the cooler was clean, but inside it was gummed up. After flushing and replacing the oil, the problem vanished.”
These stories highlight the importance of both external and internal maintenance.
Diagnostic Strategies
To pinpoint overheating causes:
- Visual Inspection
Check for debris buildup on cooler fins. Use compressed air or low-pressure water to clean.
- Belt Tension Test
Press the belt midway between pulleys. It should deflect no more than 1/2 inch. Replace if cracked or loose.
- Tensioner Movement Check
Manually pivot the tensioner arm. If it’s stiff or seized, clean and lubricate or replace.
- Oil Temperature Monitoring
Use an infrared thermometer to measure oil cooler inlet and outlet temperatures. A large differential suggests poor flow.
- Flush and Replace Oil
Drain and flush the system with a compatible solvent. Refill with manufacturer-recommended oil.
To avoid overheating:
- Clean cooler fins daily in dusty environments
- Replace fan belts every 500 hours or when worn
- Inspect tensioner arm quarterly
- Flush oil cooler annually or every 1,000 hours
- Use high-quality oil with proper viscosity (typically SAE 10W-30 or 15W-40 for Deutz engines)
- Avoid prolonged full-load operation in extreme heat
- Engine oil capacity: ~9.5 liters
- Normal operating oil temperature: 85–105°C
- Max safe oil temperature: 120°C
- Fan belt lifespan: ~500–800 hours
- Cooler cleaning interval: daily to weekly depending on conditions
While the 873 is no longer in production, owners can enhance cooling performance with:
- High-efficiency aftermarket oil coolers
- Synthetic oil with better thermal stability
- Digital temperature gauges with alarms
- Vibration-resistant fan belts
- Removable mesh screens to reduce debris ingress
In 2024, a small engineering firm in Minnesota began offering retrofit kits for legacy Bobcat models, including the 873. These kits include upgraded oil coolers, tensioners, and digital monitoring systems. Field tests showed a 30% reduction in overheating incidents.
Meanwhile, a vocational school in Texas added the 873 to its training fleet, using it to teach students about oil-cooled engine systems and thermal diagnostics.
Conclusion
Overheating in the Bobcat 873 is a manageable issue when approached with methodical diagnostics and preventive care. Its oil-cooled Deutz engine offers simplicity and reliability, but demands attention to airflow, belt tension, and internal cleanliness. With proper maintenance and thoughtful upgrades, the 873 can continue to perform reliably in even the harshest conditions—proving that smart design and operator diligence go hand in hand.
