5 Key Causes of Turbocharger Failure and How to Prevent Them

Turbochargers are known for their reliability, with fewer than 1% failing due to manufacturing defects. However, around 95% of turbo failures are caused by external factors such as oil starvation, contamination, or foreign object damage. Before installing a new turbo, it’s crucial to identify the root cause of the failure of the previous unit, as replacing the turbo without addressing the underlying issue could lead to another failure.

Here are the top five reasons why turbochargers fail and how to prevent them:

1. Foreign Object Damage (FOD)

One of the leading causes of turbocharger failure (accounting for 80% of cases) is foreign object damage. This happens when debris such as dirt, dust, a shop rag, or even a small bolt enters the intake side of the turbo, causing damage to the compressor wheel’s blades. If foreign objects come into contact with the compressor wheel, you'll notice impact marks on the leading edge of the blades and possible scarring in the inducer bore.

Common Cause: A dirty or poorly maintained air filter is the most common culprit of foreign object intrusion.

Solution:

• Always use a high-quality air filter.
• Keep it clean if it’s reusable, or replace it at the recommended intervals if it’s disposable.

2. Overspeeding

Overspeeding occurs when the turbocharger is pushed beyond its design limits, causing excess drive pressure and making the shaft spin faster than intended. When this happens, the turbine (exhaust) wheel is the first to fail, and the entire turbo system can suffer significant damage. In extreme cases, parts of the turbo can even exit the exhaust at high speeds.

Solution:

• Maintain a boost-to-drive pressure ratio as close to 1:1 as possible (1:1.5 is generally acceptable).
• Use a wastegate to control excess pressure or upgrade to a larger turbine housing to help manage exhaust flow.

3. Oiling Issues

Proper lubrication is critical for the longevity of a turbocharger. Lack of oil or poor oil quality can quickly damage the bearings, leading to shaft play and contact between the turbine or compressor wheels and their housings. Oil contamination, such as coolant or fuel mixing with the engine oil, can exacerbate this problem.

Solution:

• Use high-quality, fresh oil and replace the oil filter as per the engine manufacturer's recommendations.
• Regularly change the oil to keep it free of contaminants and ensure it’s the correct grade for your engine.
• Clean or replace oil inlet pipes to remove sludge or carbon buildup that could restrict oil flow.

4. Seal Leaks

Modern turbochargers often use dynamic seals to prevent oil from leaking into the intake or exhaust sides. However, factors such as excessive crankcase pressure (common in high-horsepower engines) or worn seals can lead to oil leakage into these areas. When the center section of the turbo is over-pressurized, it forces oil into the intake or exhaust, causing significant damage.

Solution:

• For high-performance applications, consider upgrading to a better crankcase ventilation system or even a dry sump oiling system to manage excessive pressure.
• If your turbo is showing signs of oil leakage, it may be time for an overhaul or replacement.

5. Electronic Actuator Malfunction

Variable Nozzle Turbine (VNT) turbos, which are often electronically controlled, can suffer from actuator failure. The REA (Rotary Electronic Actuator) or SREA (Simple Rotary Electronic Actuator) controls the movement of the vanes in these turbos. If the actuator fails, it can compromise the performance of the turbo and ultimately cause failure.

Solution:

• Replace the faulty actuator or, in some cases, the entire turbocharger if the actuator is irreparable.

Conclusion:

Turbochargers are robust components that can last a long time if properly maintained. By avoiding the common pitfalls of foreign object damage, overspeeding, oiling issues, seal leaks, and electronic actuator malfunctions, you can ensure that your turbo operates at its best for years to come. Always identify the cause of failure before installing a new turbo to prevent recurring issues and unnecessary repairs.