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How to Service a Turbocharger

Posted by Scott Goldfarb on

Many car enthusiasts get hyped by the mention of turbochargers. However, this forced induction device must be thoroughly maintained to ensure it functions properly. That’s why we want to elaborate on how to service a turbocharger and explain the most important steps during the process.

Turbochargers are praised for their precise parts and high speeds. Thus, regular maintenance and service ensure their safety and functionality. To prepare you for the upcoming service, we will review each step of the process separately and highlight the most important matters.

Keeping the turbocharger clean and well-maintained will save you from costly replacements and repairs. So, continue reading to discover how to service a turbo and what to watch out for during the process.

How to Service a Turbocharger
Source: shutterstock.com/ Photo Contributor: Palitsyn Evgenii

How to Service a Turbocharger

The process of servicing a turbocharger involves six delicate steps. To ensure the best results, thoroughly following this guide is important. Here’s the step-by-step process of servicing a turbocharger:

  • Pre-service check
  • Disassembly
  • Inspection
  • Cleaning
  • Reassembly
  • Testing

Pre-service check

Before one indulges in a full turbocharger service, one should conduct a pre-service check. This includes evaluating the vehicle's condition before beginning the overhaul. When experiencing certain issues, remember that the turbocharger may not be their primary cause.

Thus, it’s always recommended to be mindful of any underlying problems that may cause turbo damage. For that reason, a quick diagnostic check must be conducted before servicing the turbocharger. Some of the most common issues people experience are:

Lack of power

Many people decide to service their turbocharger due to experiencing a lack of power. However, this issue may be caused by several factors. 

First, you should check the filter, hoses, and pipes. They should all be thoroughly cleaned and checked to ensure they’re in good condition.

The next step is to focus on the fuel injection system. Besides ensuring its condition, you should check if it’s been correctly adjusted.

You should also examine the exhaust system to see if the two previous elements function properly. Blockage and damage to this area can often cause a lack of power. It’s important not to rush the process and pay close attention to the catalyst and DPF. 

Excessive oil consumption or smoke

Another common reason why people turn to servicing a turbocharger is due to excessive oil consumption or smoke. However, a very common cause of such issues is the air filters and oil drain pipes. So, before you begin the overhaul, check for any restriction or blockage that may be causing the problem. 

Next, you should also check the engine oil specifications. It’s of utmost importance that it corresponds with the car manufacturer’s recommendations. If everything seems alright with these elements, you should also check the hoses and joints to ensure they’re in good condition.

Another common trigger for such an issue is excessive pressure in the engine crankcase. Thus, you should check the engine breather system to ensure it’s functioning properly. In case carbon and oil deposits are found in the turbine or exhaust manifolds, it may be a sign of lubrication problems in the engine block.

Noisy performance

The last reason many people turn to turbo servicing is noisy performance. For this reason, there are two main culprits that you want to check.

The first are the pipework and support brackets. These parts often cause noise when they’re damaged or loose. Thus, you should always check if the connections are good and done properly.

The second common cause of this problem is the intercooler. When checking this part, focus on finding any cracks or leakages causing the noise. 

Disassembly

After the pre-service check is complete, the turbocharger must go through a careful disassembly process. As mentioned, they have precise parts that require knowledge of the relative positions during this process for effective maintenance. To better understand this process, we will go over each step separately:

  • Removing the casting
  • Removing the wheels
  • Removing the thrust bearing 
  • Removing the floating ring from the compressor
  • Removing the floating ring from the turbine

Removing the casting

The best tip during the disassembly is to mark the turbine, compressor, and intermediate casing positions. In most cases, the turbine casting is removed first, followed by the compressor. When it comes to removing the intermediate casing, you should use two M10 screws to eject it from the turbine one successfully.

Removing the wheels

The next step is to remove the compressor wheel nut, which separates it from the turbine wheel. A special tool is then needed to remove the compressor impeller and flat key.

Removing the thrust bearing 

After that, you’ll need to focus on the compressor end at the middle casing. In this area, you’ll once again need to use the two M6 screws to remove the thrust bearing and air seal plate. Removing the thrust plate and its gasket simultaneously is especially important for achieving the best results.

Removing the floating ring from the compressor

Once you’ve reached the compressor’s end, you must remove the moving piece and the floating ring. When doing this step, don’t forget to pair them because putting them in the wrong place can cause further issues.

Removing the floating ring from the turbine

Once you finish the compressor, you should focus on the turbine end. Here, you’ll need to take out the air seal plate and ring. All you need to do is follow the same steps as with the compressor, and you won’t run into any trouble.

Removing the spring snap ring is another detail you need to look out for in this section. Since it’s located outside the turbine-bearing seat, it’s best to use pliers for the cause. Then, once again, you remove the turbine’s moving piece and floating ring and keep them in pairs.

Cleaning

Once all the turbocharger parts have been removed, the main focus should be cleaning them. It's important to note that people prefer different ways and practices regarding this process. 

The first way to clean the components is by dipping them in gasoline or diesel. This will remove any potential dirt and allow you to inspect the parts better. However, you should thoroughly clean the parts so you don’t mistake dirt for damage.

The second way to clean turbocharger components is with a hot jet wash. This system must use a non-caustic soap solution to ensure the safety of the parts. They’re usually placed in a jet wash cabinet where the right solutions are applied to clean them thoroughly.

Some other ways to clean these components are abrasive blast and vibratory cleaners. The first uses high-velocity propelling of abrasive media to remove any leftover dirt from the parts. Thanks to the compressed air, it can easily dislodge any unwanted residue from the desired surface.

On the other hand, vibratory cleaners are also called vibro cleaning machines and tumbler cleaners. They offer a batch-finishing process, which is highly effective for cleaning most metal parts.

Inspection

When the turbocharger has been cleaned, a thorough inspection needs to be conducted to ensure the quality and safety of the parts. When doing this process phase, it’s important to consider the component’s technical requirements. Here are the main aspects of each part and how to know if they need to be replaced.

First, you need to focus on the turbine, impeller, and air-sealed ring and plate. These components should not have signs of damage for the turbo to function properly. Furthermore, you should look for grease, carbon deposits, and other debris. They usually appear on the surface of the parts and are easily spottable. 

Next comes the moving piece, thrust washer, and the floating, snap, oil seal, and nozzle rings. These parts mustn’t be broken, bent, deformed, or burnt. If you notice such issues, it’s best to either try to repair them or replace them with new functioning components.

Lastly, you should inspect the oil and air seal rings. For this section, it’s important to check the elasticity and opening and side clearances. These parts have strict technical requirements and should be replaced if they’ve reached their specified limit.

Reassembly

After you’ve checked and cleaned the turbocharger parts, they should be reassembled. In general, you have to follow the reverse order of the disassembly to ensure the components are in their right places. 

Most people start with assembling the main bearings and the bearing housing first. Then, they move to the thrust system and backplate, which are installed on the already assembled bearings. 

Once these components are put in place, the next step is to insert the turbine wheel through the bearing housing and backplate. To complete the rotating assembly, all that’s left to do is add the compressor wheel and shaft nut. Even though it’s quite obvious that the assembly position should never be exchanged, here are the two main steps you should watch out for during this process:

  • Compressor impeller and turbine
  • Compressor impeller and main shaft

Compressor impeller and turbine

First, you must ensure that the compressor impeller and turbine meet the primary balance requirements. This is especially important if you’re planning on replacing the turbine shaft. 

When replacing this part, it’s recommended that you replace it together with the compressor impeller. Furthermore, you’ll also need to recalibrate the dynamic balance to ensure the components are working properly.

Compressor impeller and main shaft

The next important aspect of the reassembly process is installing the mentioned compressor impeller onto the main shaft. In this phase, you’ll need special tools to tighten the fixing nut to a specified torque. It’s also important to measure the gap between the said impeller and the air seal plate since the value should be from 0.4 to 1.2mm.

Additionally, you should measure the axial gap between the turbine and the air seal plate because it has to be from 0.5 to 2mm. Do not, in any case, try to assemble the impeller by tapping because it may cause issues in the long run.

Testing

Once you’ve completed the service, the last step is to test the turbocharger to ensure it functions properly. Even though many turbocharger services have their preferred testing methods, one of the most effective ones is VSR testing. VSR stands for vibration sorting rig and is used to test the turbocharger cartridges. 

This type of test should always be conducted before installing the turbine and compressor housings to ensure the best results. Since the VSR machine used for testing is a high-speed turbocharger balancing device, it can easily track high-frequency and out-of-balance conditions. 

This testing is conducted by first installing the cartridge into the VSR cabinet. Then, you connect oil pressure to it, and the unit is spun around with additional air pressure to operating speeds. This way, the VSR will pick up any issues present and alert you about them.

Some of the most common problems detected by this machine are unusual oil pressure readings, turbo whine, and oil leakage at the seal. Once these issues are corrected, you can install the compressor and turbo housings and finish the turbocharge service.

Testing the Turbocharger
Source: shutterstock.com/ Photo Contributor: taro911 Photographer

Conclusion

After discovering how to service a turbocharger, it’s important not to rush the process. Remember that many specific parts are involved in the process. Besides being careful during the disassembly, they’ll have to be put back in their exact order.

Furthermore, it’s important to use efficient cleaning methods to ensure all the dirt and debris have been removed. Then, you should thoroughly inspect each part for damage to decide if any repairs or replacements are needed. Once you’ve reassembled the turbocharger, it’s recommended that you test it to ensure no hidden issues arise.

If you don’t have any prior experience in the subject, always put your trust in an experienced professional service. This way, an expert team will guide you through the process to ensure the best results.

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