Effects of foreign object damage on turbochargers laid bare

If a vehicle is suffering from rattling or grinding noises during operation and drivers experience loss of engine power, this could be due to foreign object damage on the turbocharger.

A foreign object refers to anything that enters the turbocharger through the air or exhaust inlets. When a foreign object enters the turbocharger, its performance will be affected, potentially resulting in considerable damage. Tom Wright, our Product Manager, explains various reasons why this can happen, as well as offering signs to look out for and ways to prevent it.

“It’s critical that technicians pay special attention to the condition of other components within the vehicle to mitigate the risks posed to the turbocharger,” says Wright.

“There are various scenarios that can result in contaminants in the turbocharger air supply, all of which can have devastating effects on the system’s longevity. This includes previous turbocharger failures leaving remnants in the system, debris from engine components or objects left within intakes during regular servicing.”

Causes of foreign object intake can also include faulty or damaged turbo hoses, which inadvertently cause small particles to enter through any gaps in the system.

A turbocharger repair specialist will be able to diagnose foreign object damage if there are visible marks on the compressor or turbine blade, or pitting marks around the compressor inlet and nozzle ring assembly vanes.

If the turbine or compressor blade is found to be damaged, the turbocharger should stop being used immediately, as the rotor balance will be affected, and this could impact its service life.

“To prevent turbo failure from foreign object damage, we recommend that technicians always replace or fully clean intake pipes and check for debris before fitting a replacement turbo,” says Tom Wright. All air hoses should be free from contaminants and blockages. Hoses should also be checked regularly as part of routine turbocharger servicing.

“Technicians should always use the correct air filter suitable for the specific vehicle model, and regularly replace it according to the manufacturer’s recommendations. As with intake pipes and air hoses, following a turbocharger failure, the filter and surrounding intakes should be cleaned to eliminate any debris or fragments that could harm the new turbocharger,” Wright says.

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Expert advice on turbocharger overheating

If a vehicle is suffering from lack of power, the exhaust is smoking excessively, or there are abnormal whirring noises, it could be because the turbocharger is overheating.

Product Manager, Tom Wright, explains the symptoms, causes, and the steps that vehicle technicians can undertake to prevent an untimely turbocharger failure.

“If a turbocharger is suspected of overheating, it’s critical to undertake a thorough inspection, as it can cause serious issues in the long term,” says Wright. “While it’s not a reversible process, complete failure can be prevented if problems are diagnosed and resolved quickly.”

Turbocharger specialists can establish if a turbocharger has been affected by overheating by conducting a thorough examination of the internal components.

“The heat-soak effect sustained during periods of overheating will cause discolouration to the turbine shaft and bearing housing, as well as internal components, such as the thrust washer and flinger, without necessarily displaying other symptoms of excess wear,” comments Wright.

If the issue is not addressed, this can lead to sections of the turbocharger turbine blades displaying becoming fractured, bent, or damaged. Furthermore, excessive heat can cause carbonisation of the lubricating oil, leading to catastrophic turbocharger failure.

Thankfully, preventing overheating conditions and the resultant strain on a turbocharger is relatively straightforward.

“Vehicle technicians should check that there are no leaks in the cooling lines, and that on diesel-powered vehicles, the DPF is not blocked. Drivers can also take steps to ensure longevity of their car’s turbocharger by giving it time to cool after long journeys,” says Wright.

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How a blocked diesel particulate filter can damage a turbocharger

Not enough attention is being paid to the impact of blocked diesel particulate filters (DPFs) on turbochargers, says Tom Wright, product manager at precision-engineered turbocharger specialist Melett.

If technicians don’t check for a DPF issue when installing a replacement turbo, it could lead to the untimely failure of the new turbo, Wright warns. All diesel-powered vehicles manufactured since late 2009 feature a DPF, which is designed to capture soot and remove it from the exhaust gas as the vehicle is driven. To keep the DPF working efficiently, regeneration processes are employed to burn off any excess soot.

However, there are many factors that can stop these regeneration processes from working effectively, such as the type of fuel and oil used, driving style, vehicle age and mileage. Vehicles that are regularly driven on short or low-speed journeys often don’t reach the required temperatures to activate the regeneration process.

“Blockages prevent exhaust gasses passing through the exhaust system at the required rate, which can cause increased exhaust gas temperature and back pressure,” Wright says. “This can affect the turbocharger in a number of ways, ranging from oil leaks and performance degradation to component failure.”

Increased back pressure forces the exhaust gas through the piston ring seals and into the turbo core assembly (CHRA), leading to excessive temperatures, within the CHRA. This prevents efficient oil cooling within the CHRA, and can even carbonise the oil, restricting oil feeds and causing wear to the bearing systems particularly on the hot side of the turbo. These high temperatures can also lead to failure of the turbine wheel through high cycle fatigue.

A blocked DPF can force exhaust gas through the smallest of gaps, including the clearances in the bearing housing variable nozzle turbine (VNT) lever arm and turbine housing wastegate mechanisms. If this happens, carbon build up can restrict movement of the levers, affecting performance of the turbo. Oil leaks into the compressor housing may also occur as a consequence of exhaust gas forcing its way into the CHRA from the turbine side and forcing oil through the oil seal on the compressor side.

“It is critical that any DPF issues are identified and rectified prior to installing a replacement turbocharger,” says Wright. “Failure to address the original problem means the replacement turbo will be subjected to the same operating environment as the previous unit, and will ultimately suffer the same failure in a significantly shorter amount of time.”


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Remanufactured turbochargers offering cost savings as inflationary pressures bite

There is no better time to offer a remanufactured turbocharger to customers as the current economic climate has led to a perfect storm for vehicle owners.

From a customer viewpoint, remanufactured products using high-quality components can be considered the same as a new product, providing a more attractively priced alternative to the original.

Turbocharger remanufacturing is increasing in popularity within the aftermarket, as an original equipment turbo can often be very expensive to replace. Remanufacturing preserves as much of the material in the original product as possible, therefore using less raw materials than in the manufacture of new products.

Remanufacturing involves vehicle parts being rebuilt to a standard equal to, or greater than, the original manufacturer specification. At times, aftermarket design improvements mean that remanufactured parts often outperform the original equipment (OE) originals, as any design defects can be engineered out.

The process ensures that the original design and quality specifications are all met, so technicians and end users can be confident in the quality of the remanufactured vehicle part they receive.

In the past, low-quality components from unreputable suppliers have been used in the remanufacture of turbochargers, which has created preconceptions about the reliability of remanufactured parts. However, this opinion about remanufacturing has changed significantly in recent years.

A professional turbo repairer will carry out pre-production checks of all old units to ensure that only the best quality turbo core is selected for remanufacturing. All parts are inspected for damage and wear. Any worn or damaged parts will be replaced. The core assembly is balanced and only when a unit passes the final balancing tests is it deemed ready for final assembly.

Tom Wright, product manager said: “The entire UK economy is being gripped by the cost-of-living crisis, and the garage and automotive sector is no exception.”

“With service providers and customers concerned about spending, it’s important to consider the benefits in cost offered by remanufactured components, with significant reductions in price when compared to original equipment (OE) products.

“Cost savings aside, we’re reminding the industry that there’s no compromise on safety and part quality. The use of high-quality components in remanufacture ensures a long-term, sustainable approach on vehicle repair and servicing.”

Automotive Parts Remanufacturers Association (APRA) Europe recently reported that1 remanufacturing saves millions of tons of carbon equivalent emissions, 85 percent of raw materials and 55 percent of energy compared with new production, meaning remanufacturing is sustainable and resource friendly.

“Remanufacturing provides additional benefits on a wider scale, with the environment benefitting from carbon savings and reduced emissions from not having to extract raw materials in the manufacturing process of a new turbocharger,” Wright says.

Here at Melett, we understand the importance of using the correct materials and are committed to supporting the turbocharger repair market with the highest quality parts and service.

For more information about us, including technical resources or how to find your nearest turbo specialist, click here.

1: APRA Europe, https://apraeurope.org/?method=ical&id=1920

Why turbocharger removal is unnecessary to diagnose an oil leak

Oil leaks can be caused by several factors, but technicians shouldn’t rush to remove the turbocharger in the event of a leak to diagnose a fault, says Product Manager, Tom Wright.

There can be a variety of reasons why a turbocharger may leak oil with the main factor being incorrect pressure within the compressor and turbine housings. “Before removing the turbo, technicians should check the location of the oil leak as different diagnoses can be given depending on which end the leak is located. Over 90 percent of turbocharger failures are consequential of other issues, so identifying the root cause before replacing a turbo is key.” says Wright.

When looking for causes of oil leaks at the compressor end of the turbocharger, a good place to start would be to inspect the air intake hose for damage, splits, leaks and incorrect fitment. At the turbine end, oil leaks can be caused by warped exhaust flanges, incorrect gaskets, or cracks in the turbine housing – something that is sometimes only visible when the turbo is hot.

If there is a kink, bend, or partial blockage in the oil return pipe, this will cause the oil pressure to build up in the bearing housing, resulting in leaks from both turbine and compressor ends.

It is worth noting that removal of intake or exhaust pipes to inspect the turbocharger for oil leaks will cause leaks to occur. In doing so, you inherently cause a pressure drop which allows oil to leak from the turbocharger.

To prevent oil leaks when fitting a turbocharger, technicians should ensure that the air systems and oil drain systems are clear from any blockages. They should always fit the correct oil gaskets for the turbocharger. They are also advised to not use silicone in an attempt to seal oil inlet and oil outlets. Silicone can become easily dislodged and can restrict or block oil passages as a result.

Technicians working on turbochargers should also check the vehicle’s exhaust system, including the diesel particulate filter and catalytic converter, to make sure no leaks or blockages are present.

Using the correct parts and high-quality equipment is crucial to successful turbocharger maintenance.

Melett is renowned for producing OE quality products to help the turbo aftermarket produce the highest quality repairs. All Melett turbochargers are built, balanced and flow tested in the UK to the strictest quality standards to ensure OE performance during operation.

To help identify common failures in warranty situations and to provide advice on how to prevent future failures occurring, check out our series of educational technical videos.