3.5 Turbochargers: breakdowns and possible causes
Several factors can cause vibration, including imbalanced rotors, misaligned bearings, damaged turbine blades, or worn-out components. Other potential causes include inadequate lubrication, excessive air or gas flow, or issues with the turbocharger’s foundation or mounting. It can be harmful to the turbocharger’s performance and reliability, as well as to other components in the engine system.
2. Run-out or slower acceleration
Misalignment between the rotor and the housing can cause the rotor to rub against the housing and generate noise. Another possible cause is damage to the turbocharger’s bearings, which can cause the rotor to wobble or become unbalanced, resulting in reduced performance and acceleration.
3. Turbocharger Moisture
Moisture is mainly caused by the high humidity levels of the combustion air in marine engines, which is often drawn from the sea. Sea spray and incomplete combustion can also contribute to moisture build-up. Incomplete combustion can result in unburnt fuel and water vapour entering the turbocharger. Additionally, when the engine is shut down, the turbocharger cools down quickly, leading to condensation on its surfaces.
4. Exhaust gas temperature is higher than normal at operating power and corresponding engine speed
Contaminated or partially blocked air filters can make the turbocharger work harder to deliver the required amount of air, thus increasing the exhaust gas temperature. If the exhaust system is partially blocked or damaged, the exhaust gases will not be able to flow out of the engine freely. This can cause back pressure, which increases the temperature.
5. Discharge pressure is lower than normal at operating power and engine speed
Lower discharge pressure in a marine turbocharger can be caused by worn or damaged components, such as the compressor or turbine wheel, intercooler, piping, or air filter. Carbon buildup, leakage, poor maintenance, and debris can also restrict airflow and reduce pressure.
6. Discharge pressure is higher than normal at operating power and engine speed
Higher discharge pressure can be caused by increased engine load, carbon buildup, reduced compressor efficiency, restricted air intake, worn turbine blades, or a malfunctioning wastegate.
Sea water exposure and other environmental factors can cause corrosion, leading to cracks or holes in the housing of a turbocharger. Improper assembly, overheating, and vibration can also cause leaks. Regular inspections can help identify and address potential issues before they cause damage or downtime
8. Lubricating oil darkens quickly (rolling bearing)
Darkening of the lubricating oil can be caused by oxidation, contamination, overheating, wear, and improper maintenance. Contaminants like soot, dirt, or metal particles, and high temperatures from the turbocharger can cause the oil to darken.
9. Oil leakage during autonomous lubrication
No pressure or excessively high pressure in the sealing chamber can lead to oil leakage