What is overspeeding and why does it damage turbos?

Overspeeding is a term used when a turbo is operating well above its normal operating limits, and the resultant strain of overspeeding can cause untimely failure of the turbo, as well as the internal combustion engine (ICE) and associated components, Tom Wright, our product manager warns.

One of the main causes of overspeeding is insufficient airflow from the turbocharger to the engine, which could be caused by a torn air pipe, a blocked air intake or a leak between the compressor and the engine. If there are any leaks, cracks or poor seals between the compressor and the engine, the turbo will have to work much harder than it should to deliver the required air levels to the engine.

“When the engine needs more air than the turbocharger can supply, overspeeding occurs. The turbocharger then has to work outside of its usual operating limits which can, in extreme cases, cause blade damage including partial loss of blades, fatigue fractures or a burst compressor wheel,” says Wright.

A common symptom of overspeeding is the presence of the ‘orange peel’ effect on the back face of the compressor wheel. This is created by expansion and contraction.

When the compressor wheel is subjected to overspeeding, it grows in size and this expansion causes cracks between the grain boundaries of the material.

In mild cases, the component will return to its original state like elastic but in most cases these cracks begin to grow and eventually, part of the hub can break away.

Another cause of turbo overspeeding can be remapping the electronic control unit (ECU). As drivers of some performance vehicles look to maximise the fuel efficiency or performance of their cars, some turn to remapping or ‘chipped’ engine work, which involves altering the car’s ECU to deliver a different power map or torque range. This can then take the standard factory fitted turbocharger outside the operating range it was design to work within.

Wright advises when diagnosing a turbocharger fault, technicians should be wary that as a consequence of overspeeding the signs of other failure modes such as insufficient lubrication can be present. This is due to the barrier created by the oil film within the bearing systems failing. In turn, this causes contact between components as overspeeding occurs and the turbo fails.

For more information on overspeeding and the preventative measures you can take, visit our dedicated technical article: Common turbo failure – Overspeeding. You can also check out our series of educational technical videos which help identify common failures in warranty situations and provide advice on how to prevent future failures occurring,

In the winter months, don’t forget to think turbo!

As the trusted aftermarket brand for precision engineered turbochargers and parts, we’re urging technicians to stay on top of turbo maintenance this winter and are offering best practice tips to help customers prolong the life of their turbo as temperatures plummet.

Lubrication is a key element to ensuring a turbocharger is doing its job correctly. Therefore, it is essential to check that a vehicle’s oil is the correct grade. When fitting a replacement turbo, it is important that the oil system has been primed and is in full working order. If this is not the case, it can lead to premature failure.

Many turbo-related issues are simply down to neglect, and with more than a third of drivers expected to skip servicing their vehicle in a poll[1] taken in 2022, we’re advising technicians to not only encourage regular servicing, but also to ensure the vehicle’s oil and oil filter is checked and replaced to protect the turbo from damage caused by contamination.

Another top tip for motorists is to adapt their driving habits during the colder weather, especially if the vehicle has not been run for long periods. Simple changes such as waiting a few minutes before driving at high revs to allow the engine to warm and oil to flow through the turbocharger. This prevents damage to components within the turbocharger. By avoiding revving the engine, unnecessary stress on the turbo is avoided.

For more turbo tips and helpful video resources, please visit www.melett.com/technical

[1] https://www.thisismoney.co.uk/money/cars/article-11511699/Third-drivers-likely-delay-skip-cars-service-save-money.html

We’re reminding technicians of top tips on how to ensure their turbo story has a fairy tale ending this Valentine’s Day.

As manufacturers build smaller engines but look to maintain performance with higher power delivery, turbochargers have become essential across the market, especially as emissions requirements become more stringent.

Because of this, more turbo-related issues are arriving with technicians, and our product manager Tom Wright has several top tips for best practice to ensure technicians’ close encounters with turbochargers go without a hitch this coming Valentine’s.

“As over 90 percent of turbocharger failures are consequential of other on-vehicle issues, it is essential that the root cause of the problem is identified before fitting a new turbo. This will save time down the line and will prevent any potential issues with the new turbo,” says Wright.

Oil contamination is one of the top reasons for a turbocharger failure – a number of factors can play a part here, so it is essential that the oil system is serviced correctly when fitting a turbocharger to ensure debris from the previous failure does not remain in the system. If the technician doesn’t carry out this step, the new oil can become contaminated also, causing premature turbo failure within minutes, warns Wright.

To avoid failure through insufficient lubrication or oil contamination, oil inlet pipes should be inspected, cleaned or preferably replaced to remove carbon deposits or sludge that could restrict oil flow and/or contaminate the new oil. In addition, in all installations of a turbocharger, priming the oil feed and oil systems is a must, as this will prevent the turbo from instant failure through a lack of lubrication caused by a delay in the delivery of oil.

Modifying driving style is another way to prolong the life of the turbocharger and other vehicle components. This is as simple as allowing time for the engine and turbocharger to warm up before accelerating hard and cool down before switching off. “Operation temperatures will be significantly higher if a turbo has been worked hard and therefore it needs time to cool, as shutting the engine off immediately after a spirited drive can cause the oil to carbonise within the turbo.” Wright adds.

Driving style can also impact the operation of the diesel particulate filters (DPF), which have been compulsory to fit to diesel vehicles since 2009. In turbocharged, diesel-powered vehicles, technicians should advise drivers to perform regular longer journeys to allow DPF regeneration to occur successfully. This can be achieved via a 10-15 minute journey on a motorway at mid-high revs.

A blocked DPF prevents exhaust gas passing through the exhaust system at the required rate. As a result, back pressure and exhaust gas temperatures increase within the turbine housing of the turbocharger, affecting the turbocharger in a number of ways, including problems with efficiencies, boost levels, oil leaks, carbonisation of oil within the turbo and exhaust gas leaks from the turbo. “It’s therefore important that technicians maintaining, and servicing diesel-engine cars pay attention to the condition of the DPF in the event of turbo failure to prevent premature failure of the new turbocharger,” Wright adds.

Just as with the exhaust system, any blockages, restrictions, leaks or contaminants in the air intake system will impact the turbochargers performance and could lead to failure. Wright recommends replacing the air filter on an annual basis to help minimise dirty air passing through the turbo. Contaminated air with pollutants, dust and debris can lead to poor performance and foreign object damage to the compressor. Blocked or restricted filters can lead to incorrect pressures in the compressor housing and therefore oil leaks, which can lead to failure.

At Melett, we’re renowned for producing OE quality products to help the turbo aftermarket produce the highest quality repairs. With an in-house team of highly qualified mechanical engineers, our turbochargers are subject to rigorous engineering and testing processes to ensure they match OE specifications. All our turbochargers are built, balanced and flow tested in the UK to the strictest quality standards to ensure OE performance during operation.

Turbochargers have become essential to manufacturers seeking to build engines smaller but with similar or higher power delivery to meet emissions requirements.

This has inherently led to more turbo-related faults arriving at the hands of technicians, and Melett product manager Tom Wright has several top tips for best practice to avoid scary costs for garages and their customers.

“As over 90% of turbocharger failures are consequential of other on-vehicle issues, getting to the bones of the problem and identifying the root cause before fitting the new turbo is key.

“Oil contamination is one of the top killers of a turbocharger and can happen in various ways. When fitting a turbocharger, if the oil system is not serviced correctly, debris from the previous failure can remain in the system, which can contaminate the new oil and cause premature turbo failure within minutes,” Wright says.

To avoid failure through insufficient lubrication or oil contamination, oil inlet pipes should be inspected, cleaned or preferably, replaced to remove carbon deposits or sludge that could restrict oil flow and/or contaminate the new oil. In addition, in all installations of a turbocharger, priming the oil feed and oil systems is a must, as this will prevent the turbo from instant failure through a lack of lubrication caused by a delay in the delivery of oil.

Modifying driving style can prolong the life of the turbocharger and other vehicle components. This is as simple as allowing time for the engine and turbocharger to warm up before accelerating hard and cool down before switching off.

“If a turbo has been worked hard then operating temperatures will be considerably higher. It’s important to allow the turbo time to cool, as shutting the engine off immediately after a spirited drive can cause the oil to carbonise within the turbo.” Wright adds.

Driving style also impacts the operation of the diesel particulate filters (DPF), which have been compulsory to fit to diesel vehicles since 2009. In turbocharged, diesel-powered vehicles, it’s important for drivers to perform regular longer journeys to allow DPF regeneration to occur successfully. This can be done via a 10-15 minute journey on a motorway at mid-high revs.

A blocked DPF prevents exhaust gas passing through the exhaust system at the required rate. As a result, back pressure and exhaust gas temperatures increase within the turbine housing of the turbocharger.

“Increased exhaust gas temperature and back pressure can affect the turbocharger in a number of ways, including problems with efficiencies, boost levels, oil leaks, carbonisation of oil within the turbo and exhaust gas leaks from the turbo,” Tom Wright explains.

“It’s therefore important that technicians maintaining, and servicing diesel-engine cars pay attention to the condition of the DPF in the event of turbo failure to prevent premature failure of the new turbocharger.”

Just as with the exhaust system, any blockages, restrictions, leaks or contaminants in the air intake system will impact the turbochargers performance and could lead to failure.

“It’s recommended that the air filter is replaced annually to ensure that dirty air passing through the turbo is minimised. Contaminated air with pollutants, dust and debris can lead to poor performance and foreign object damage to the compressor. Blocked or restricted filters can lead to incorrect pressures in the compressor housing and therefore oil leaks, which can lead to failure,” Wright concludes.