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How to Repair Turbo Diesel?

Posted by Scott Goldfarb on

Like all cars, turbo diesel vehicles need to be repaired occasionally because malfunctions can appear like with any car. Knowing how to repair turbo diesel will save you thousands of dollars at the mechanic.

Sometimes you can’t avoid having your car fixed because not everyone has the time to learn about becoming their own mechanic. But more often than not, the problems are small and easily fixable in a matter of minutes.

All it takes is to know how to read the signs your car is giving you and to respond adequately. In the article, we will help you overcome the most common problems that arise in turbo diesel engines.

How to Repair Turbo Diesel

Even though turbo diesel engines are famous for their durability, there still comes a time when you simply have to perform a repair to a certain part. Otherwise, you risk allowing it to cause bigger damage and even total engine collapse, which could cost a fortune later.

Performing regular checkups and servicing the engine with the advised frequency will further increase its durability and prevent many defects. Change the oil and oil filter every 10,000 miles, and don’t go longer than 12 months. 

To maintain optimal performance and fuel economy, replace the air and fuel filters every 15,000 to 30,000 miles. Perform regular inspections for coolant, turbocharger, battery, timing mechanism, etc.

While you may not always be able to identify every issue, it's essential to familiarize yourself with the most noticeable turbo problems and learn how to prevent and address these issues effectively.

These are some of the malfunctions that occur and the ways to repair them:

1. Turbocharger failure

This problem most commonly arises from engine negligence. Not changing the oil and filters causes contaminants like dirt and debris to accumulate. The particles increase the viscosity of the oil and take away from its efficacy. 

The oil acts as a lubricant for the moving parts of the turbo, like the turbine wheel and compressor wheel. Lack of lubrication increases friction and causes it to wear more rapidly.

Other common causes for the failure of the turbo can include bad driving habits such as long idling, hard acceleration from cold, and revving the engine beyond its safe limit.

Turbocharger failure

Source: shutterstock.com / Photo Contributor: Cooperfield

Recognizing turbocharger failure

  • Decreased power: If you notice a decline in performance, the chances are that the turbocharger cannot generate the necessary boost pressure. You can recognize the decrease in power during acceleration.
  • Excessive smoke: If you notice an unusual amount of smoke coming out of the exhaust, it means that there’s oil in the combustion chamber. The internal seals prevent that from happening but over time, they can wear out, allowing leakage. If the oil enters the exhaust, it is going to burn together with the fuel, but it will result in more smoke.
  • Whining noise: Hearing an unusual noise during acceleration is a failure indicator of the rotating parts. This occurs when there’s a lack of lubrication to these components.

How to repair the turbocharger

Depending on the extent of the damage, the turbo may require a complete or partial replacement. Inspect the elements of the turbocharger and find the broken part. You can determine this visually by examining the turbo and all its parts.

You can also inspect the exhaust system for signs of excessive soot or oil. This is an indicator of a broken turbine or faulty exhaust manifold. Diagnostic tools can provide data revealing the problems with sensors or electronic controls.

Once you find the faulty part, simply replace it with a new one. If the failure is related to oil contamination, it’s important to clean the turbocharger and its components.

2. DPF failure

The Diesel Particulate Filter is usually in the same chamber as the catalytic converter. Its role is to control the emissions and reduce the soot emissions that are a byproduct of the combustion process.

Failure of the DPF can be caused by exhaust system issues such as leaks or malfunctions and poor fuel quality. Using your diesel car only for short trips at low speeds prevents the engine from achieving the necessary exhaust temperature.

DPF failure
Source: shutterstock.com / Photo Contributor: Janar Sinivali

Recognizing DPF failure

  • Reduced performance: Failure of the diesel particulate filter usually manifests through reduced engine performance and bad fuel economy. This is because a clogged DPF causes excessive pressure in the exhaust.
  • Frequent regeneration cycles: Regeneration cycles commonly occur during highway driving. Once the exhaust gasses reach a specific temperature, it naturally burns down the soot. However, the car has its regeneration cycles. Frequent activation of the regeneration cycles may be a sign of DPF failure. The car’s engine control unit will activate the regeneration cycle when there’s soot buildup. 
  • Exhaust problems: Dark smoke that persists even during normal driving conditions is a common indicator of DPF failure. With the excessive dark smoke, there’s often a strong smell of diesel.
  • Difficulty starting: A clogged DPF can lead to problems with starting the engine. Whistling noises and a strange idle sound often accompany it.

How to repair DPF failure

If you have determined that your car has suffered DPF failure, you can perform several and see how to repair turbo diesel DPF failure. If the filter is not damaged, cleaning the soot buildup can be enough to repair the DPF. 

You can use specialized cleaning agents, and there are pneumatic cleaning methods like air pulse and reverse flow cleaning. However, these take a lot of work to perform.

The best chance you have is taking your car out on the highway. The high temperature of the gasses will burn off soot, but only if the engine is not completely clogged. If the damage is too extensive, you must go to the mechanic.

Finally, you can replace the DPF system with a new one. You must ensure the new part is compatible with the vehicle’s model and emission standards.

3. Fuel injector issues

The fuel injector is responsible for delivering fuel into the combustion chamber. The fuel injector should deliver fuel in the right amount and at the right time. If the fuel is contaminated or of poor quality, it can lead to deposits in the fuel injector.

Fuel injectors require regular maintenance as it’s part of the engine that’s susceptible to clogging. Carbon or debris buildups in the nozzles can affect the spray timing and quantity patterns.

This is why it's one of the most important spare parts you should have on hand.

Recognizing fuel injector issues

  • Misfiring engine: A clogged fuel injector will lead to misfires in the engine because the injector will fail to deliver the right amount of fuel. Consequently, the car loses power and has an uneven engine operation. The engine will sound different, and the vibrations will increase while idling.
  • Bad fuel economy: Lousy fuel consumption will result in inefficiency if the fuel isn’t appropriately delivered. 
  • Strong smell: You can sense both the outside and inside of the car can have strong smells, indicating your car is leaking fuel from the fuel injector. 

How to repair fuel injector issues

You can use cleaning solutions on the fuel injector to unclog the nozzles that deliver the fuel. These substances are poured into the fuel tank to mix with the fuel, and they will work on cleaning the fuel injector while you drive. You should be careful and add just the right amount of dosage.

If this doesn’t work, you might need to replace the fuel injector or go to the mechanic to try professional methods of cleaning and repairing.

4. Glow plug failure

The glow plug’s primary role is to heat the air inside the combustion chamber. During cold weather, the air inside the chamber may be too cold for the combustion process, preventing the car from starting. 

Recognizing glow plug failure

  • Signal issues: Your car will signal issues with the glow plug on the dashboard.
  • Difficulty starting: During cold weather, failure to start the car can point to issues with the glow plug. An increase in smoke can accompany this.
  • Misfiring engine: Combustion requires a certain amount of heat in order to be effective. Bad combustion will lead to a misfiring engine and rough idling.

How to repair glow plug failure

In the case of failure, you will need to replace the glow plug. Disconnect the battery and remove the glow plug wiring from the cylinder to replace it with a new device. Once connected, secure the plug with a wrench.

Glow plug failure

Source: shutterstock.com / Photo Contributor: ERIK Miheyeu

5. Timing belt/chain issues

The belts and chains are always exposed to heat and engine vibration. That is why they’re prone to deterioration. Lack of maintenance and timely replacement can lead to multiple issues with the engine.

Recognizing timing belt/chain issues

  • Bad timing: A worn-out belt or chain will provide off timing. This leads to untimely combustion and lousy performance.
  • Strange engine noise: Weird engine noises like rattling or clicking can indicate timing belt or chain issues. 
  • Difficulty starting: Improper timing can lead to difficulties with starting the engine.

How to repair timing belt/chain issues

Perform a visual inspection of the belt's condition. Determine its condition, and if there’s too much wear, you should replace it regardless of the car’s performance. 

You should replace the timing belts every 60,000 to 100.000 miles.


Turbo diesel engines are durable machines that can last long with proper maintenance. Like any vehicle, they often go through issues that require fixing. Having basic knowledge and skill on how to repair turbo diesel yourself and save money and time. 

Some common issues that occur are with the turbocharger, the diesel particle filter, the fuel injector, and timing.

Therefore, in order to preserve durability and avoid any faults, you need to do frequent check-ups.


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