Troubleshooting Overheating Issues in the Big Cam 855 Engine: The Role of Dirt and Other Contributing Factors

[MikePhua]

Heavy-duty engines, like the Cummins Big Cam 855, are the backbone of many industrial machines, from trucks to construction equipment. These engines are designed to run efficiently under strenuous conditions, but just like any powerful machine, they are susceptible to issues that can affect their performance. One of the most common and troublesome issues that can arise is overheating, which can lead to severe engine damage if not addressed promptly.
In this article, we will explore the overheating issue in the Cummins Big Cam 855, a widely used engine in construction and trucking, and identify the potential causes of this issue. While dirt is often the primary culprit, there are several other factors that could contribute to engine overheating.
Understanding the Cummins Big Cam 855
The Cummins Big Cam 855 is a high-performance engine used primarily in diesel-powered trucks, agricultural equipment, and construction machinery. Known for its durability and power, the Big Cam series has been a popular choice for over three decades. The engine's turbocharged design and high displacement make it suitable for handling heavy loads and operating in demanding conditions.
However, like any engine, the Big Cam 855 requires careful maintenance to ensure it runs efficiently. If any component in the cooling system fails or becomes blocked, it can lead to overheating, which can cause long-term damage if left unaddressed.
Identifying Overheating Symptoms
The first step in troubleshooting an overheating issue is recognizing the symptoms. An engine running hot can exhibit several signs:

1. Rising coolant temperature gauge: If the temperature gauge on the dashboard is reading higher than normal, it could indicate that the engine is running hotter than it should be.
   
2. Coolant loss: If the engine is losing coolant without visible leaks, it could be evaporating due to excessive heat.
   
3. Poor engine performance: Overheating can cause the engine to lose power, run rough, or experience misfires.
   
4. Steam or smoke: In extreme cases, you may notice steam or smoke coming from under the hood, indicating that the engine has overheated to a dangerous level.
   

If any of these signs are present, it’s essential to shut the engine down immediately and investigate the cause of the issue.
Dirt: A Primary Culprit in Overheating
One of the most common reasons for overheating in the Big Cam 855 engine is dirt accumulation, particularly in the cooling system. Dirt can obstruct airflow to the engine, block the radiator, or cause the cooling fins to become clogged, all of which reduce the engine’s ability to shed heat effectively. Let’s dive deeper into how dirt affects different components of the cooling system.
Radiator and Cooling System
The radiator plays a crucial role in keeping the engine cool. It relies on airflow to dissipate heat from the coolant, but dirt, dust, and debris can accumulate on the radiator fins, blocking the airflow and reducing the radiator’s efficiency. In extreme cases, the radiator can become entirely blocked, leading to severe overheating.
Dirt can also clog the coolant passages in the engine, reducing the flow of coolant and preventing it from effectively transferring heat away from the engine.
Air Intake and Turbocharger
The air intake system of the Big Cam 855 is responsible for bringing cool air into the engine for combustion. If the intake system becomes clogged with dirt, it can reduce airflow to the engine, leading to poor performance and excessive heat generation.
Additionally, the turbocharger—which helps force more air into the engine to improve performance—can also suffer from dirt buildup. The turbo relies on clean, cool air to operate efficiently. If dirt enters the intake system, it can damage the turbo, reducing its efficiency and causing the engine to overheat.
Other Contributing Factors to Overheating
While dirt is often a primary cause of overheating in the Cummins Big Cam 855, several other factors can contribute to the problem:
Low Coolant Levels
One of the simplest causes of engine overheating is low coolant levels. If the coolant is not at the proper level, the engine may not have enough fluid to circulate and absorb heat. Over time, this can cause the engine to run hotter and eventually overheat.
Faulty Thermostat
The thermostat regulates the flow of coolant through the engine, ensuring it stays within the optimal temperature range. A faulty thermostat can get stuck in the closed position, preventing coolant from circulating and causing the engine to overheat. It is a common part that can fail in older engines or after prolonged use.
Failed Water Pump
The water pump is responsible for circulating coolant throughout the engine and the radiator. If the pump fails, the coolant will not flow properly, leading to overheating. In some cases, the pump may wear out due to age or lack of maintenance, causing it to lose its efficiency.
Clogged Cooling System
A clogged cooling system can also lead to overheating. This can happen due to the accumulation of debris, rust, or sediment in the radiator or coolant passages. A blockage in the system restricts the flow of coolant, preventing it from absorbing heat and maintaining proper engine temperature.
Exhaust Gas Recirculation (EGR) Valve Issues
The EGR valve helps reduce nitrogen oxide emissions by recirculating exhaust gases back into the engine’s intake. If the EGR valve becomes clogged or fails, it can lead to higher temperatures in the engine, as the system is no longer functioning properly. This can result in increased engine heat and potentially lead to overheating.
Preventive Measures and Maintenance Tips
To prevent the Big Cam 855 from running hot, regular maintenance is key. Below are some essential tips for keeping the engine cool:

1. Clean the radiator regularly: Ensure the radiator is free of dirt and debris, especially in environments with lots of dust.
   
2. Check coolant levels: Regularly monitor the coolant levels and top them up if necessary.
   
3. Inspect the thermostat: Test the thermostat periodically to ensure it’s functioning correctly.
   
4. Examine the water pump: Make sure the water pump is circulating coolant properly and is free of leaks.
   
5. Replace the air filters: Keep the air intake and filters clean to ensure proper airflow to the engine.
   

Conclusion
The Cummins Big Cam 855 is a robust engine capable of handling demanding tasks, but like all heavy-duty engines, it requires proper maintenance to avoid overheating. While dirt is often a significant contributor to overheating issues, factors such as low coolant levels, a faulty thermostat, and a malfunctioning water pump can also play a role.
By understanding the causes of overheating and implementing regular maintenance routines, operators can ensure their Big Cam 855 engines run efficiently for many years. Preventive care, such as cleaning the radiator and air intake system, checking coolant levels, and inspecting key components, can go a long way in preventing costly repairs and downtime.
Staying proactive and vigilant about engine health will keep the Big Cam 855 running cool and powerful, ensuring that it continues to perform at its best on the job.