Common Turbo Faults

Problem with your turbocharger?

 

If you’re concerned about a problem with your turbocharger it is important to get it checked out. Driving with a damaged turbo can destroy your engine and be dangerous.

 

How to recognise turbo failure

 

Before replacing your turbo, a diagnostic check can determine the issue with your turbo and eliminate other causes of engine problems. A diagnostic check will also find the reason for the damage to your existing turbo before fixing or replacing it so that the problem can be avoided in the future. Below lists some common warning signs that can let you know whether your turbo needs maintenance or repair.

 

Engine power/boost loss:

If your vehicle is displaying a lack of power; accelerating more slowly than usual or isn’t capable of reaching the speeds it once could, it is worth checking the condition and cleanliness of your filter, hoses and pipes. Most boost issues will immediately make an engine management light come on and may produce a code (the vehicle may also enter limp mode). It is advised to check movement in the wastegate/VNT to assess for carbon build up and impaired movement in the VNT; this is especially important on vehicles such as the Ford Transit. The fuel injection system should also be correctly adjusted and in good condition, and your exhaust system should be checked for signs of damage or blockages.

 

Engine noise:

Failing turbochargers often make loud whining or whistling noises when under boost. Therefore, noise that appears after the turbo had previously been running well could be a cause for concern. Excess noise from your engine may be caused by loose or damaged pipework and support brackets, or by a damaged compressor wheel. It is also important to check for cracks or leaks in the intercooler. If the noise appears directly after fitting a new/remanufactured unit, the problem is most likely to be a leaking gasket. 

 

A smoking exhaust and/or increased oil consumption:

If your vehicle is emitting excessive exhaust smoke, blue, grey or black exhaust smoke, or is consuming more oil, it is important to check that the air filters are not blocked or restricted. A distinctive smoke from the exhaust could be caused by oil leaking into the exhaust system, for example, due to a cracked turbo housing or damaged internal seals. As the oil burns off the smoke will develop, which may be more noticeable when the engine revs are increased following the vehicle standing idle. It is also worth checking that the correct oil has been used and that the oil drainpipe is clean and unrestricted. Hoses and joints should be in good condition and the engine should be checked for excessive pressure in the engine crankcase. The engine breather system should also be working correctly and, if there are oil or carbon deposits on the exhaust manifolds or in the turbine, the engine block should be checked for lubrication problems.

 

Check engine warning lights:

The computer diagnostics on the majority of modern cars will recognise turbo faults, causing the check engine light to become illuminated. However, given that the check engine light could be caused by a range of faults, you will need to inspect your engine to identify the type of problem you have.

 

The boost gauge:

A number of turbocharged vehicles have boost gauges that measure the amount of boost produced by your turbo. If this gauge is not going up as normal then there may be a problem with your turbo.

 

Inspecting your turbo

 

In order to identify the type of problem you have, you could conduct a visual and/or benchtop inspection of your turbo.

 

Visual Inspection:

You could conduct an initial visual inspection yourself at home. To start with, you should look for signs of oil, impact damage and contact between the compressor wheel and housing, as well as excessive movement. The symptoms of turbo failure are similar to other problems in the engine, and so it is worth checking the correct functioning of the exhaust and breather systems as well as the air filter. Assuming these look OK, you can access the turbo by removing the air filter.

Begin by examining the turbo’s exterior for loose connections or signs of oil. Then, the compressor wheel should be checked to ensure it is clean with no signs of damage. You could also check that the wheel is not touching the housing.

In addition, you could check the exhaust side of the turbo by removing the exhaust pipe until you can see the turbine wheel. The wheel should look clean and the blades should look undamaged. The turbo housing can likewise be checked for cracks and leaks.

This inspection could reveal numerous problems:

  • Excessive heating

  • Loose mounting

  • Compromised air hoses

  • Burnt compounds and odour

  • Blocked filters

  • Turbo fractures

 

Benchtop Inspection:

Following an initial visual inspection, you could perform a more detailed benchtop inspection of your dismounted turbo. Alternatively, Recoturbo could assess your turbo for you using our diagnosis and inspection service. A benchtop inspection can reveal problems that are difficult to spot based on an initial visual inspection, such as:

  • Broken compressor vanes

  • Blocked valves and/or actuators

  • Damaged hoses

  • Leaking/blown seals

  • Damaged circuitry

  • Clogged air filter

 

The causes of turbocharger damage

 

It is important to understand what caused the fault to occur before repairing or replacing your turbo as a damaged turbo may be a symptom of an underlying problem. There are several common causes of turbocharger damage:

 

Oil starvation/lack of lubrication:

To work effectively, a turbo needs a regular flow of clean oil. Oil starvation is a common cause of turbo faults, which is caused by either a drop in oil pressure or a delay between the oil reaching the turbo. Given the speeds of which turbo shafts can rotate, it is vital that the shaft and bearings are lubricated with oil. There are various tell-tale signs of turbos that have failed due to old starvation, including broken shafts, failed bearings, turned-up blades, missing turbine nuts, heat discolouration, and/or bearing pick up material on the shaft. The friction between metals caused by material transfer and high temperatures can be caused by a restricted oil inlet supply. A more general lack of lubrication can be caused by poor quality lubricants, the use of liquid gaskets or incorrect gasket placement. A vehicle’s oil and oil filter should frequently be changed to prevent excess carbon deposits and contaminants from building up and causing abrasive damage to your turbo.

With regards to oil leaks, anything that causes excess crankcase pressure can cause issues. Leaking injector seals or cracked injectors have been known to cause heavy oil leaks. Generally, the seals or piston rings will only leak if there is a pressure imbalance. In the majority of cases, the piston rings are only affected by DPF issues (overheating of the turbine wheel causing the piston rings to overheat, leading exhaust gases to back-up and force their way back into the turbine housing). These sometimes cause contamination whereby the journal bearings have failed and allowed excess play of the shaft to wear the piston ring grooves and piston rings.

 

Oil contamination:

Contaminated oil, such as particles or debris in the oil supply, could cause your turbo to fail. As the oil passes between them, particles score the shaft and bearings as well as affecting the seals (and causing potential oil leaks). In turn, this wears away at these components causing their failure. A high concentration of carbon in the oil can be caused by irregular oil changes or poor maintenance, whereas major work to the engine could cause steel shot in the oil, resulting in bearing damage.

 

Overspeeding and excessive temperature:

A turbocharger works based on increased air pressure in the engine. If there are damaged seals, leaks or cracks between the compressor and engine the turbo must work harder to function correctly. Overspeeding may cause the almost instant failure of your turbo or it may slowly damage your turbo over time, thus causing it to fail in the future. Overspeeding occurs when the turbo is pushed beyond its designed parameters or outside the manufacturer’s specification, for instance, by a split boost pipe or sticking EGR/boost control valve, causing the blades to become chipped or fractured. Other causes of overspeeding and the failure of the compressor of turbine wheels include engine malfunction, poor maintenance and unauthorised performance upgrades.

 

Foreign objects:

Sometimes, small objects such as broken engine components, stones, dirt or dust can enter the turbine or compressor housing of a turbocharger via the compressor inlet or turbine inlet. At high speeds, these objects can lead to imbalances and cause impact damage and abrasion to the compressor wheels and turbine blades. Over time, this damage will reduce the turbo’s performance. This problem can help to be prevented by regularly servicing your air filter and by checking your turbo for debris or loose connections.

 

Sticking VNT:

A sticking VNT (Variable Nozzle Turbine) is a common problem that can cause the failure of turbos. Carbon deposits can cling to the turbo’s exhaust housing, including the nozzle ring and, as these deposits build, the variable ‘vanes’ (the flaps inside a turbocharger that are operated by the actuator and regulate exhaust gases in the turbine housing) begin to jam and become locked in position. As a result, an insufficient amount of air will enter the engine causing issues with over fuelling and even more carbon build up. When the Nozzle Assembly sticks, the driver may experience a lack of power (boost faults), vehicle smoking and potentially complete turbo failure. Fortunately, in many cases this issue can be easily resolved by cleaning the VNT.

 

Passing oil:

Heavy carbon build up could cause turbos to pass oil; a turbo may stop functioning correctly when oil is unable to properly drain away or when part of the shaft has excessive carbon deposits, meaning the oil that lubricates the shaft is prevented from entering the drainage area. When a vehicle’s oil drain is blocked or the engine is breathing heavily, the oil passed into the exhaust can cause greyish smoke. Before refitting your new or repaired turbo, it is advisable to also replace the engine breathers and to ensure the drain is clear in order to prevent the same issue from reoccurring.

 

Other:

Occasionally, some causes of turbo failure can be difficult to see with the human eye. For instance, heat stress, cracks, moisture ingress, wear and tear or too much exhaust gas temps (EGTs) can cause the failure of turbos. When the cause of your damaged turbo is unclear, it is best to allow a specialist such as Recoturbo to undertake a diagnosis and inspection of your turbo.

 

Recommendations for servicing

A turbocharger should last as long as the engine and does not require special maintenance. Though, there are steps you can take to reduce the chance of turbo failure. For example, the following should be undertaken in accordance with the manufacturer’s service instructions:

  • Regular oil changes

  • Maintenance of the oil and air filter systems

  • Oil pressure control

 

Regular maintenance can help prevent damage to your turbo caused by things such as foreign bodies, contaminated oil, lack of lubrication or excessive temperatures.

 

How we can help

If you suspect a fault with your turbo or notice any of the warning signs, it is important to get your turbo checked as quickly as possible to prevent further damage. At Recoturbo, we provide high-quality repairs to turbochargers on a wide range of vehicles.

For those of you who are mechanically minded, you could inspect your turbo yourself to diagnose the problem. Then, you could either send your turbo to us to be repaired or rebuilt, or you could order a new or remanufactured turbo from us.

 

For more information, call our expert sales team on 01302 595 123

Given that turbocharger components are high-precision machines built to close tolerances, it is usually best to allow a specialist to inspect your turbo. Recoturbo can inspect and diagnose the fault with your turbo and will provide you with a report that details your fault, as well as the range of servicing options available to you. Not only will this provide you with peace of mind, but it ensures that your turbo will only be replaced if necessary.

 

For more information, call our friendly technical team on 01302 896 460

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