Solving Overheating Issues on the Volvo L70E Wheel Loader

[MikePhua]

The Volvo L70E and Its Engineering Legacy
Volvo Construction Equipment, a division of the Swedish industrial giant Volvo Group, has been producing wheel loaders since the 1950s. The L70E, introduced in the early 2000s, was part of the E-series lineup that emphasized fuel efficiency, operator comfort, and electronic control integration. Powered by a Volvo D6D engine rated at approximately 145 horsepower, the L70E quickly became a favorite in municipal, forestry, and aggregate operations. With thousands of units sold globally, the L70E is known for its smooth hydrostatic transmission, load-sensing hydraulics, and robust cooling system—though that last feature can become a point of concern under certain conditions.
Understanding the Cooling System Architecture
The L70E uses a multi-stage cooling system designed to regulate engine temperature, hydraulic fluid, and transmission oil. Key components include:

• Engine-mounted belt-driven fan
  
• Radiator core with aluminum fins
  
• Charge air cooler (intercooler)
  
• Hydraulic oil cooler
  
• Thermostat-controlled coolant flow
  
• Temperature sensors feeding into the ECU
  

The fan operates at variable speeds based on engine load and ambient temperature, controlled by a viscous clutch. This system reduces noise and fuel consumption but can fail to deliver adequate airflow if components wear or clog.
Common Causes of Overheating
Operators have reported overheating in the L70E under heavy load or high ambient temperatures. Typical causes include:

• Clogged radiator fins due to dust, chaff, or oil mist
  
• Malfunctioning viscous fan clutch
  
• Faulty thermostat or temperature sensor
  
• Airlock in the coolant system
  
• Hydraulic oil overheating from continuous high-pressure operation
  
• Debris buildup between the radiator and intercooler
  

In one case from Queensland, a contractor using an L70E for road base loading noticed the temperature gauge climbing rapidly during afternoon shifts. After inspection, they found that the radiator was packed with fine dust from crushed limestone, reducing airflow by nearly 80%. A thorough cleaning with compressed air and water restored normal operating temperatures.
Diagnostic Steps and Field Testing
To pinpoint the source of overheating:

• Check coolant level and inspect for leaks
  
• Examine radiator fins with a flashlight for blockage or damage
  
• Test fan clutch engagement by observing fan speed at idle and under load
  
• Use an infrared thermometer to compare inlet and outlet temperatures across the radiator
  
• Scan ECU for fault codes related to temperature sensors
  
• Inspect hydraulic lines and cooler for signs of restriction or bypass
  

Technicians often perform a pressure test on the cooling system to detect internal leaks or head gasket failure. A drop in pressure over time may indicate a breach in the system.
Solutions and Preventive Measures
To resolve and prevent overheating:

• Clean radiator and cooler fins weekly in dusty environments
  
• Replace the thermostat every 2,000 hours or if temperature fluctuations occur
  
• Inspect and replace fan clutch if engagement is inconsistent
  
• Flush coolant system annually and use OEM-approved antifreeze
  
• Install a debris screen or reversing fan in high-dust applications
  
• Monitor hydraulic oil temperature and reduce cycle times if overheating persists
  

Some operators retrofit their L70E units with electric fans or auxiliary coolers, especially in tropical climates. While these modifications can improve cooling, they must be carefully integrated to avoid electrical overload or reduced airflow efficiency.
A Story from the Field
In rural Alberta, a gravel pit operator ran an L70E for stockpile loading during summer. The machine began overheating after two hours of continuous operation. After ruling out coolant leaks, the mechanic discovered that the fan clutch had failed, causing the fan to spin at idle speed regardless of engine load. Replacing the clutch and cleaning the radiator restored full cooling capacity. The operator later installed a temperature alarm with a cab-mounted buzzer to catch future issues early.
Design Considerations and Long-Term Reliability
The L70E’s cooling system was engineered for balance between efficiency and performance. However, its reliance on variable fan speed and compact cooler layout makes it vulnerable to airflow restriction. Volvo later addressed some of these concerns in the H-series loaders by increasing cooler surface area and improving fan control algorithms.
To maintain long-term reliability:

• Keep service intervals consistent and document temperature trends
  
• Train operators to recognize early signs of overheating
  
• Use telematics to monitor coolant and oil temperatures remotely
  
• Replace aging hoses and clamps before failure
  

Conclusion
Overheating in the Volvo L70E is often a symptom of airflow restriction, component wear, or hydraulic overload. With methodical diagnostics and preventive care, operators can restore cooling performance and extend machine life. Whether working in dusty quarries or urban job sites, the L70E remains a capable and efficient loader—provided its cooling system is kept clean, responsive, and well-maintained.