Causes of turbo damage in diesel and petrol engines

Turbocharger failure is almost always a consequence of a more complex problem, not an independent defect. In 90% of cases, it indicates malfunctions in the engine or related systems. Therefore, to avoid replacing turbines one after another, it's important not just to replace the unit, but to determine the true causes of turbo failure engine damage. In this blog, we'll conduct a complete analysis of what really leads to turbocharger failure: both from the perspective of the unit itself and external factors. If you perform preventive maintenance on time, you'll definitely be able to protect your car's engine from repeated costly repairs.

When the cause is in the turbocharger itself

Although turbocharger failure is most often related to external factors, there is a specific list of causes when the problem lies within the turbocharger itself. In this case, the compressor wheel and turbocharger shaft suffer most frequently. These elements operate at high speeds, subjected to extreme loads - and any violation of operating conditions leads to serious damage.

However, in practice, we encounter various cases. Among common ones, it can also be a factory defect, material fatigue, wear of sliding bearings, overheating, or an unbalanced rotor. Sometimes the cause is foreign objects entering the intake tract or the hot part of the turbine, leading to mechanical damage to the turbine blades and the formation of scratches on the shaft.

And yet these are already consequences. If we talk about deeper causes, most internal turbocharger malfunctions develop along one of three main scenarios. Next, we'll examine each of these cases in detail to understand why turbines fail in diesel or gasoline engines and how to prevent recurrences in the future.

Mechanical damage: causes of turbocharger failure from the inside

The most vulnerable parts in mechanical damage to a turbocharger are the compressor wheel and turbocharger shaft. These elements rotate at a colossal speed - up to 200,000 rpm. Any deviation from the norm: contamination, increased pressure, or a foreign object - almost always leads to integrity violation.

One of the most common causes of turbo failure engine damage is the appearance of gaps in the intake tract. Through microscopic openings, dust particles and abrasives penetrate the system, creating a sandblasting effect on the impeller. With constant exposure, this causes blade wear, and as a consequence - balance disruption. Parallel depressurization leads to loss of boost pressure and oil leakage, creating additional load on the turbocharger.

Another factor is the failure to replace the air filter on time. A clogged filter cannot effectively catch dust and debris. As a result, solid particles still reach the impeller surface, leading to the gradual formation of micro-damages. The danger of such wear is that it's gradual, therefore unnoticeable immediately, but over time it leads to complex failure of the variable geometry turbine and disruption of its geometry.

The cause can also be a clogged oil drain from the turbine. If the oil drain pipe is clogged or narrowed, oil begins to enter the intake tract, where under the influence of temperature, it turns into coke deposits. These hard fractions settle on the compressor blades and moving elements with variable geometry, disrupting their operation up to complete blockage.

Separately, we should mention carbon deposits in the engine intake manifold as another cause of turbocharger failure. Under the influence of temperature, oil begins to "bake" - turning into a thick, sticky mass, similar in consistency to modeling clay. This baked deposit settles on the shaft blades and in the variable geometry area of the turbine, causing sticking of moving elements. With significant accumulation, this can lead to complete blockage of the geometry change mechanism, which reduces power, worsens engine responsiveness, and causes errors on the dashboard.

Mechanical damage can also occur from the hot side of the turbine. For example - debris from engine cylinders getting into the scroll. Most often this happens when the oil control rings of the piston are destroyed, which becomes the cause. Such cases are rarely diagnosed in time, and when they get inside, they break the shaft and cause turbocharger damage.

It's worth mentioning separately such a situation as a cracked exhaust manifold. A micro-crack often appears due to a clogged diesel particulate filter (DPF) or catalyst, when the pressure of exhaust gases rises to a critical level (up to 5 bar). Under such pressure, the manifold overheats and is no longer able to withstand the load. As a result, the car experiences a decrease in boost pressure, power loss, Check Engine light activation, and ECU errors, including the famous P0299. Moreover, such cracks are very difficult to diagnose without disassembly, and the turbine already begins to lose productivity.

Any of the mentioned causes can provoke a chain reaction, resulting in guaranteed diesel turbo failure or a failure in a gasoline engine.

Oil maintenance errors as causes of turbocharger failure in diesel engines

Every modern engine is designed with precise calculation of specific parameters of load, temperature regime, and working fluid specifications. Therefore, engine oil not only lubricates parts but forms an oil film that protects against overheating, friction, and premature wear. When one of these parameters is violated, it's primarily the turbocharger that suffers. Problems with the engine's oil system most often become an invisible trigger that starts a chain reaction of malfunction.

Causes of turbocharger failure due to problems with lubricants are especially common among cars with diesel engines, where the temperature is quite high, and the load on the turbine is constant. Among them:

• Oil starvation - with a lack of oil in the system, or when using a technical fluid of inappropriate viscosity, or when not observing the recommended value of temperature stability, the oil film constantly tears and doesn't form properly. The shaft begins to literally grind the bearing walls, which can lead to the shaft breaking in half. It looks like increased wear and play, followed by failure. However, this is one of the most common causes of turbocharger failure in diesel engines.
• Excessive oil pressure. Often associated with oil pump malfunction. High oil pressure leads to seal damage and engine oil leakage into the intake tract or hot part of the turbine, resulting in oil deposits forming on the blades, leading to uneven load distribution.
• Untimely oil change. When change intervals are violated, oil gradually loses its protective properties. Under the influence of high temperature and aggressive operation, it begins to coke and precipitate inside the turbine housing. These deposits disrupt the operation of moving elements and cause premature shaft wear.
• Clogged oil drain. In this case, back pressure is created in the turbine housing, oil doesn't have time to drain and simply overfills the system. Lubricant gets into the intake, exhaust, and even onto the turbine blades, where it burns out. This becomes the cause of coke formation and, consequently, difficulty in the rotational movement of the blades.
• Violation of oil supply pressure. Turbocharger failures can also be associated with improper design of the return drain. If the turbine drain pipe is bent or clogged, used oil doesn't drain but creates excessive pressure in the housing. The result is oil leakage from the "cold" side of the turbine, smoke from the exhaust pipe, and reduced boost productivity even with operational internal components.
• Turbine operation under asymmetrical pressure. For example, if resistance or blockage forms on the intake or exhaust side, imbalance occurs. As a result, oil begins to be squeezed from the opposite side of the turbine housing - through seals, pipes, or connections. This leads to oil leaks, smoking, and a drop in boost pressure even with operational internal components.

Based on the list of causes of turbocharger failure, we conclude that oil "not according to specification" may have different viscosity, insufficient thermal stability, or low resistance to oxidation. Even with proper replacement, it will still lead to accelerated wear of the turbocharger.

An additional factor can be a clogged exhaust gas recirculation system (EGR). In this case, pressure in the exhaust system increases, the turbine begins to work in unstable conditions, and oil is squeezed through seals on the "cold" side despite sound mechanics.

When fuel becomes the cause of turbocharger problems

Even a properly functioning turbine will quickly fail if the fuel supply to the engine is incorrectly set up. With insufficient fuel, the temperature of exhaust gases increases — this causes overheating of the hot part of the turbine and accelerates the wear of blades and bearings.

If too much fuel is supplied, it doesn't have time to burn completely. The residues enter the turbine, forming fuel deposits from local explosions, which provokes further problems with the turbine. In both cases, the boost works unstably.

A separate risk is refueling with fuel that doesn't meet the manufacturer's requirements. Increased ash content, sulfur, or low cetane number lead to contamination of the turbocharger and become causes of turbocharger damage.

Actuators as causes of hidden turbocharger failures

In modern engines since 2023, most engine control systems have become electronic. This also applies to turbochargers, whose operation is coordinated mainly through electronic actuators. These are compact drives that regulate turbine geometry and boost load in real-time. However, behind their precise operation lies a structural detail: they are all made of plastic. In original and high-quality versions — it's heat-resistant caprolactam (PA6).

On one hand, this material is resistant to overheating and friction. On the other — it has a natural strength limitation. Over time, gear wheels, sensors, micro-drives, and transmission mechanisms begin to wear down. This usually happens after 150-200 thousand kilometers, but can occur earlier if the actuator is not of the best quality.

What's important: actuator failure does not cause immediate turbocharger failure, but disrupts its operation:

• geometry freezes;
• boost pressure is not adjusted;
• engine power decreases.

At the same time, there are no obvious mechanical damages, so few pay attention to the initial stage of electronic actuator wear. Mainly during technical maintenance of the turbine, specialists do not check the actuator until its complete failure or conduct a quick visual assessment of its condition. Therefore, it often becomes a hidden cause of turbocharger damage, especially in modern cars with electronic control.

When causes of turbocharger failure lie in related systems

The turbocharger does not work by itself; its condition directly depends on many related vehicle systems. The domino principle applies here: if one system fails, problems with the turbine and other engine elements follow. That's why it's important to detect the interrelation of malfunctions in time, rather than just solving local problems.

Ecological systems: do EURO 6D standards really overload the turbine?

Since the introduction of EURO 6D standards (2020), the design of diesel engines has seriously changed. To meet strict emission requirements, manufacturers have implemented a whole complex of ecological control systems:

• SCR;

• EGR (низкого и высокого давления);

• DPF.

They all work in conjunction with the turbine, but it is the turbine that most often suffers from their failures. Each of these systems is designed for precise parameters of pressure, temperature, and gas volume. When even one parameter is violated, for example, when the DPF is clogged or the EGR valve works unstably, the turbine begins to operate in an abnormal mode. Asymmetrical loading of the turbocharger occurs on one side of the compressor, and the engine loses balance.

The turbocharger should function under symmetrical back pressure. But when, for example, the DPF filter gets clogged and exhaust doesn't exit at the necessary speed — the turbine works under excessive pressure. This provokes:

• increased temperature of the turbocharger housing;
• oil leaks;
• boost pressure jumps;
• accelerated wear of turbine parts.

It's important to understand: these systems are not a structural "weak link." On the contrary — ecological systems overload the turbine not because they are bad, but because they require a different maintenance culture. Shortened oil change intervals, more frequent filter replacements, the need to control fuel quality — these are all new realities to which not all drivers and service centers have adapted.

If previously standard maintenance was carried out every 10-12 thousand km, now many manufacturers recommend an interval of 7-8 thousand km. But in practice, this rule is often ignored. Hence the problems: load on EGR, DPF overheating, pressure jumps on the turbine, and consequently — causes of turbine failure without obvious external damage.

Fuel supply system: how pressure of 2500 bar affects the lifespan of a diesel turbocharger?

Few connect the condition of the turbine with the operation of injectors, but in modern engines, this connection is direct. The evolution of the fuel system has brought it to a completely new level of load: if previously the injection pressure was 500-800 bar, now it reaches 2500 bar. Such precision requires a perfect condition of the entire system, otherwise, the consequences affect the operation of the turbine.

Today, an injector is not just an injector, but a precise tool with minimal allowable error. And if previously the fuel system was rather an auxiliary part, now it is one of the main causes of turbocharger damage in diesel engines.

When injectors wear out, deviation in fuel dosage and atomization begins. And when the filter clogs, the turbine works under increased back pressure, with overheating and boost jumps.

The problem is exacerbated when the failure of one injector is often not perceived as a cause of damage. At the service center, they may replace the DPF, clean the turbocharger, but not perform diagnostics of the fuel system. The result is a repeat failure.

Thermal overload: why does the gasoline turbine suffer?

Unlike diesel engines, gasoline engines operate at higher temperatures — up to 1000°C. And overheating in this case is not an exception but a working condition, and if the system cannot cope, problems with the turbine will start prematurely.

To comply with environmental standards, such engines are equipped with a GPF (Gasoline Particulate Filter) — an analog of DPF, but designed for gasoline combustion. It is made of more heat-resistant materials, but even they do not save from wear under severe operating conditions.

The GPF operates in the zone between the exhaust manifold and the turbine, so its condition directly affects the temperature and pressure in the boost housing. With prolonged operation in harsh conditions, for example, at high RPM or in traffic jams in hot weather, heating becomes critical for:

• turbocharger housing,
• boost control valve (Wastegate),
• hot side blades and internal geometry.

As a result, the Wastegate valve loses tightness and improperly regulates pressure. The turbocharger loses control precision, and the driver feels this as underboost, loss of dynamics, hesitations during acceleration, and the overall feeling that "the engine is sluggish."

At the same time, externally the turbine may be "in order" — no leaks, blades are intact, but its behavior is disrupted. And if the wear of the GPF and thermal degradation of the housing are not taken into account, diagnostics may be useless.

What really stands behind turbocharger damage: basic principles of working with related systems

We often see the same situation: the turbine is replaced, the problem remains. And all because attention is focused on the effect, not the cause. To avoid repeated repairs and extend the life of the boost, it's worth adhering to several basic rules that in practice work better than any universal advice:

1. Check DPF, EGR, and SCR systems every 50-80 thousand km, especially if the vehicle is operated in the urban cycle.
2. With mileage over 150 thousand km, it makes sense to separately check the condition of the turbine actuator, even if everything works correctly externally.
3. Don't delay oil and filter changes — not because it's written in the manual, but because for the turbocharger, it's a matter of survival.
4. With any instability of the boost — look not only for what has failed but why it happened. Very often the answer lies outside the turbine itself.
5. If possible — once a season, do preventive diagnostics, component by component, especially if the engine is complex and modern.

And yes, we know how difficult it can be to find the source of the problem. In our practice, there have been cases when a car stood at an official service center for a month because no one could determine the cause of unstable operation. The solution was found only after a dialogue between the mechanic and the Wiatreo team, which has a deep understanding of the theory. We don't do repairs. But we know turbines. And if something is unclear — you can always ask those who understand how a turbocharger is built and what could have gone wrong.