1989 Cummins 855 Troubleshooting and Solutions

[MikePhua]

The 1989 Cummins 855 engine is a reliable powerhouse used in a variety of heavy equipment and trucks. However, like all engines, it may encounter issues that require troubleshooting and resolution. This article summarizes the common problems faced by the Cummins 855 and provides effective solutions to get your engine running smoothly again.
Common Issues with the 1989 Cummins 855

1. Hard Starting or No Start
   • One of the most frequent issues with older Cummins 855 engines is difficulty starting, especially in cold weather. This can be due to multiple causes, such as a faulty starter motor, bad glow plugs, or low battery voltage. Poor fuel quality and clogged fuel filters are also common culprits.
     
   Solution:
   • Check the battery voltage and replace it if necessary. Test the starter motor to ensure it’s functioning properly. Inspect and replace any damaged or worn glow plugs. Ensure the fuel filters are clean and the fuel is of good quality.
     
2. Low Power or Poor Performance
   • Another common issue is a noticeable reduction in engine power or overall performance. This could result from air intake restrictions, worn-out turbochargers, or a failing fuel injector. Clogged air filters or faulty boost pressure sensors can also contribute to poor engine performance.
     
   Solution:
   • Check and clean the air filters to ensure optimal airflow. Inspect the turbocharger for damage or wear, and replace if necessary. Clean or replace fuel injectors, and test the boost pressure sensor to ensure it’s working correctly.
     
3. Excessive Smoke
   • Excessive black smoke is an indication of an improper air-fuel mixture, while blue smoke usually points to oil burning in the combustion chamber. These symptoms are typically caused by problems with fuel delivery, turbocharger issues, or worn engine components.
     
   Solution:
   • Perform a thorough inspection of the fuel injectors to make sure they’re functioning properly. Replace any faulty injectors. If blue smoke is observed, check the turbocharger seals and pistons for damage or wear. You may also need to check for oil contamination in the fuel.
     
4. Overheating
   • The 1989 Cummins 855 engine can suffer from overheating due to a clogged radiator, failing water pump, or malfunctioning thermostat. Insufficient coolant or old coolant can also lead to elevated temperatures, which could damage the engine.
     
   Solution:
   • Inspect the radiator for blockages or debris and clean it thoroughly. Replace the water pump if it’s not circulating coolant properly. Check the thermostat and replace it if it’s not functioning as it should. Regularly flush and replace the coolant to maintain optimal engine temperatures.
     
5. Oil Leaks
   • Over time, seals and gaskets can wear down, leading to oil leaks. This is especially common around the valve covers, oil pan, and rear main seals. Leaking oil can lead to engine damage and loss of performance.
     
   Solution:
   • Inspect all seals and gaskets for wear or damage. Replace any worn-out seals or gaskets. Tighten bolts and ensure proper torque specifications are followed when reassembling components to prevent future leaks.
     
6. Low Compression
   • Low compression is a serious issue that can cause poor engine performance and starting problems. This could be due to worn-out piston rings, damaged valves, or a compromised cylinder head gasket.
     
   Solution:
   • Perform a compression test to identify the source of low compression. If the compression is low on one or more cylinders, consider replacing piston rings or valves. A leaking cylinder head gasket should also be replaced to restore proper compression.
     

Maintenance Tips for the Cummins 855

1. Regular Oil Changes
   • Regular oil changes are essential for maintaining the performance and longevity of your Cummins 855 engine. Use high-quality oil and replace the oil filter as recommended by the manufacturer to prevent buildup of harmful contaminants.
     
2. Fuel System Maintenance
   • Keep the fuel system clean by regularly replacing fuel filters. Dirty filters can restrict fuel flow and damage the injectors. Ensure that the fuel lines are free of air or water, which can lead to engine knocking or other performance issues.
     
3. Air Intake and Exhaust System
   • Ensure that the air intake system is clean and the air filters are replaced regularly. A clean air intake improves fuel efficiency and overall engine performance. Also, check the exhaust system for blockages or leaks that could reduce engine efficiency.
     
4. Check the Cooling System
   • Inspect the radiator, hoses, and coolant for any signs of wear or leaks. Replace the coolant as per the manufacturer's recommendation to prevent overheating and internal engine corrosion.
     
5. Monitor Engine Performance
   • Keep an eye on engine performance and listen for any unusual noises or vibrations. Regular diagnostic checks can help identify early signs of wear and tear, allowing you to address issues before they become major problems.
     

Conclusion
The 1989 Cummins 855 is a robust engine, but like all mechanical systems, it requires proper care and maintenance to perform at its best. Troubleshooting issues such as hard starting, low power, excessive smoke, and overheating can often be resolved with simple checks and repairs. Regular maintenance, including oil changes, fuel and air filter replacements, and coolant system checks, will help ensure your Cummins 855 engine continues to operate smoothly for years to come. If issues persist, consult a professional mechanic for further diagnosis and repair.