Bobcat E80 Excavator Water Pump Failure and Cooling System Restoration

[MikePhua]

The E80 and Bobcat’s Mid-Size Excavator Expansion
The Bobcat E80 is part of the company’s compact excavator lineup, introduced to bridge the gap between mini-excavators and full-size machines. With an operating weight of approximately 8 metric tons and a dig depth exceeding 15 feet, the E80 was designed for urban infrastructure, utility trenching, and light demolition. Powered by a four-cylinder diesel engine—often the Yanmar 4TNV98 or similar—the E80 delivers around 55–60 horsepower and features advanced hydraulics, load-sensing flow control, and a spacious cab.
Bobcat, originally known for its skid steer loaders, expanded into compact excavators in the early 2000s. The E80 became a popular choice in Europe and North America, especially among contractors needing a nimble machine with serious digging power. Its cooling system, while robust, relies heavily on the integrity of the engine-mounted water pump to maintain thermal stability under load.
Symptoms of Water Pump Failure
Operators may notice the following signs when the water pump begins to fail:

• Engine overheating during moderate or heavy use
  
• Coolant level remains stable but temperature spikes
  
• Reduced heater performance in cab
  
• Whining or grinding noise from pump area
  
• Visible coolant seepage around pump housing
  
• Belt slippage or misalignment
  

In one case, a contractor in Alberta reported that his E80 overheated during trenching, despite clean radiators and fresh coolant. After inspecting the pump, he found that the impeller had corroded and separated from the shaft, causing circulation failure.
Water Pump Function and System Layout
The water pump in the E80 is a belt-driven centrifugal unit mounted to the front of the engine block. Its primary role is to circulate coolant from the engine to the radiator and back, maintaining optimal operating temperature. The system includes:

• Radiator with fan and shroud
  
• Thermostat regulating flow based on temperature
  
• Expansion tank for overflow and pressure relief
  
• Hoses connecting pump, block, and radiator
  
• Belt tensioner and pulley system
  

The pump impeller, typically made of metal or composite, spins at engine speed to push coolant through the system. If the impeller wears, breaks, or detaches, flow drops and the engine overheats.
A technician in Finland discovered that a customer’s E80 had a cracked pump housing due to freeze damage. The machine had been stored without antifreeze, and residual water expanded during winter. Replacing the pump and flushing the system resolved the issue.
Diagnosis and Inspection Strategy
To confirm water pump failure:

• Check coolant level and inspect for contamination
  
• Run engine and monitor temperature rise under load
  
• Feel upper and lower radiator hoses for temperature differential
  
• Inspect pump housing for leaks or corrosion
  
• Remove belt and spin pump pulley manually to check for resistance
  
• Use infrared thermometer to scan block and radiator zones
  

If the pump spins freely with no resistance or makes noise, internal failure is likely. If coolant is present but not circulating, the impeller may be damaged or the thermostat stuck closed.
A fleet manager in Oregon added a coolant flow sensor to his E80 fleet. When one unit showed low flow despite normal temperature, he traced the issue to a partially collapsed lower hose restricting circulation.
Replacement Procedure and Component Selection
Replacing the water pump involves:

• Draining coolant and removing radiator cap
  
• Disconnecting battery and removing engine covers
  
• Loosening belt tensioner and removing drive belt
  
• Unbolting pump housing and detaching hoses
  
• Cleaning mating surfaces and installing new gasket
  
• Bolting new pump and reattaching hoses
  
• Refilling coolant and bleeding air from system
  

Use OEM or high-quality aftermarket pumps with corrosion-resistant impellers and reinforced seals. Always replace the gasket and inspect the thermostat during pump replacement.
A contractor in Texas replaced his E80’s pump with an upgraded unit featuring a stainless steel impeller. The new pump improved flow and reduced operating temperature by 5°C under load.
Preventive Measures and Long-Term Cooling Health
To extend water pump life and cooling system reliability:

• Use manufacturer-approved coolant with corrosion inhibitors
  
• Flush system every 1,000 hours or annually
  
• Inspect belts and tensioners quarterly
  
• Check for hose softness, bulging, or cracking
  
• Avoid running machine without proper coolant mix
  
• Store machine with antifreeze during winter months
  

A crew in New Zealand implemented a seasonal coolant test protocol using refractometers. The practice helped prevent freeze damage and reduced pump failures across their fleet.
Stories from the Field
In Alaska, an E80 used for pipeline trenching overheated during a summer job. The operator found that the pump pulley had seized due to bearing failure. After replacing the pump and belt, the machine ran cooler and more efficiently.
In Poland, a rental company noticed frequent overheating complaints from E80 units. After investigating, they discovered that aftermarket pumps with plastic impellers were failing prematurely. Switching to metal impeller pumps reduced warranty claims and improved customer satisfaction.
Conclusion
The water pump in the Bobcat E80 is a critical component of the cooling system, and its failure can lead to costly downtime and engine damage. With proper diagnosis, quality replacement, and preventive care, operators can ensure consistent performance and thermal stability. In a compact excavator built for precision and endurance, circulation is everything—and the water pump is its heartbeat.