855 Cummins Engine Smoking Issues and Solutions

[MikePhua]

The 855 Cummins engine is widely used in heavy machinery, trucks, and agricultural equipment. However, over time, some users report that their engines are emitting smoke. The color of the smoke can indicate different underlying issues. This article will explore the common causes of smoke in the 855 Cummins engine and provide corresponding solutions.
Common Types of Smoke and Their Causes

1. Blue Smoke
   • Cause: Blue smoke typically indicates excessive oil consumption and oil burning in the engine. The possible causes include:
     • Excessive oil consumption: If the engine's seals (such as piston rings or valve seals) are worn out, oil can leak into the combustion chamber, leading to blue smoke.
       
     • Worn engine components: Over time, engine parts such as rings and seals wear out, allowing oil to enter the combustion chamber.
       
   • Solution: Inspect and replace seals or piston rings. If the engine is old, more extensive repairs or replacement of certain components may be necessary.
     
2. Black Smoke
   • Cause: Black smoke generally indicates incomplete combustion, where the engine is not fully burning the fuel. This could be caused by:
     • Clogged air filter: A clogged air filter restricts air intake to the engine, causing incomplete combustion of fuel and resulting in black smoke.
       
     • Faulty fuel injectors: If the injectors are malfunctioning, they may over-fuel or spray fuel unevenly, leading to poor combustion.
       
     • Fuel system issues: Leaks or pressure inconsistencies in the fuel system can cause uneven fuel delivery, leading to black smoke.
       
   • Solution: Check and clean or replace the air filter. If the issue is with the injectors or fuel system, clean the injectors or replace faulty parts.
     
3. White Smoke
   • Cause: White smoke often indicates coolant entering the combustion chamber, which can be caused by:
     • Coolant leakage: A blown head gasket or cracked cylinder head can allow coolant to leak into the combustion chamber, resulting in white smoke.
       
     • Cold weather start-up: In cold conditions, white smoke may temporarily appear when starting the engine but will usually disappear as the engine warms up.
       
   • Solution: If coolant leakage is detected, replace the head gasket or repair the cylinder head. In cold weather, the white smoke will typically clear once the engine reaches operating temperature.
     

Other Common Issues and Solutions

1. Engine Overheating
   • Cause: Engine overheating can cause damage to seals and gaskets, leading to smoking issues.
     
   • Solution: Check the cooling system, including the water pump, radiator, and coolant flow. If the cooling system is functioning properly but the engine still overheats, inspect the cylinder head and head gasket for potential leaks or damage.
     
2. Exhaust System Issues
   • Cause: A blocked exhaust system or malfunctioning exhaust temperature sensors can cause the engine to emit smoke.
     
   • Solution: Inspect the exhaust system for blockages and clean it. Ensure that the exhaust components, such as sensors, are functioning properly. If sensors are damaged, replace them.
     

Conclusion
When encountering smoke from an 855 Cummins engine, the first step is to identify the smoke color and diagnose the underlying issue. Blue smoke, black smoke, and white smoke indicate different problems such as oil consumption, incomplete combustion, or coolant leakage. Regular maintenance and timely inspection of key engine components, such as fuel injectors, air filters, head gaskets, and the cooling system, can help prevent and resolve smoking issues, ensuring optimal engine performance and extending its lifespan.