Turbine Shaft Wheel Damage – AET Turbos
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Turbine Shaft Wheel Damage

Posted by Myles Doncaster on

Broken Turbine Wheel Base

Turbine Shaft & Wheel – Broken Turbine Wheel Base

This image shows a damaged turbine wheel base – look closely and you can see that the base has several sections cut out of it, which have been chipped off.

Damage like this is caused by excessive thrust bearing wear, which has caused the turbine wheel base to grind up against the heat shield – breaking off big pieces of the wheel base in the process.

This kind of damage will significantly affect the operation of any turbo, heavily reducing its effectiveness and efficiency, and is fairly likely to prevent the turbo from operating at all.

In cases like this, the only real solution is to replace the broken components, and to check and repair/replace the thrust bearing, as repairing the wheel base isn’t generally economical.

Corroded Piston Ring Seal Area

Turbine Shaft & Wheel – Corroded Piston Ring Seal Area

In this image, you can see some moderate corrosion to the piston ring seal area of the turbine shaft – the surface of the metal has become worn, pitted and roughened.

This kind of damage is caused by moisture (and salt) in the atmosphere, which gets into the turbo, and begins to eat away at the metal. Whilst generally, this means that it’s more commonly found in turbos used for marine applications, it can also be found on industrial turbochargers, and those used on farming equipment that is kept outside.

Surface corrosion damage only gets worse over time, affecting both the efficiency and output of the turbo. In addition, if you find corrosion damage on the piston ring seal area, that could mean that there is more corrosion damage elsewhere on the turbo, like on the bearing housing, compressor and seal plate.

If caught early enough, it’s sometimes possible to repair corrosion damage like this, but in many cases, it’s best to replace the affected components.

Engine Failure

Turbine Shaft & Wheel - Engine Failure

This image shows a turbine shaft and wheel with fairly serious impact damage. If you look at the wheel itself, you can see that the blades are uneven and chipped, and that the surface of the wheel has become severely pitted.

In this case, the damage was caused by major engine failure, which allowed foreign objects and melted deposits of aluminium to get into the turbine housing.

The turbine wheel in a turbocharger spins at high speeds, and even small foreign objects can cause serious damage. In this case, the deposits caused serious impact damage to the turbine, roughing up the surface of the metal, whilst chipping away and shearing off pieces of the wheel itself.

Any number of things can lead to engine failure, and the subsequent damage it causes to your turbocharger can be terminal! Unfortunately, this turbine wheel is well beyond repair, and the only course of action was to replace the turbine shaft and wheel with a new one.

Oil Supply Pressure Problem

Turbine Shaft & Wheel – Oil Supply Pressure Problem

Here, you can see an example of heavy wear and polishing damage caused to a turbine shaft and wheel by a lack of oil, either due to a poor supply, or low oil pressure.

The increased friction caused by a lack of oil lubrication has caused significant wear on the shaft. In turn, this has allowed excessive movement of the rotor, pushing it far beyond its tolerances. The excessive movement has then caused the turbine wheel profile to rub against the housing, damaging the wheels, and preventing the turbocharger from working efficiently.

In cases like this, where there is significant wearing damage to both the turbine shaft and wheel, the unit will need to be completely replaced.

To protect your turbo from this kind of damage, always ensure that your oil levels are topped up to ensure that your turbocharger gets the lubrication it needs to work properly.

Severe Oil Contamination

Turbine Shaft & Wheel - Severe Oil Contamination

In this example, you can see a turbine shaft and wheel that’s been damaged due to severe oil contamination – notice the built up oil coating both the wheel and the shaft, and the damaged blades on the wheel. On the shaft itself, you can also see where foreign objects in the contaminated oil have caused scoring damage.

Turbine shafts are manufactured to very precise tolerances, and heavy wear on the shaft like this has had a knock on effect on the movement of the unit. In this case, it’s allowed excessive movement of the rotor, which has caused the turbine wheel to rub against the housing, causing damage to the blades, and preventing the turbocharger from working correctly.

Whilst minor wear to the blades can be repaired, in cases like this, the best, most cost-effective course of action is to replace the whole unit.

Oil problems are the leading cause of turbocharger damage, which is why it’s so important to check your oil levels, change your oil frequently, and have your vehicle serviced regularly.

Worn Piston Ring Seal Groove

Turbine Shaft & Wheel – Worn Piston Ring Seal Groove (a)

This example shows a worn piston ring seal groove – in the image, you can see that the outer edge of the piston ring seal groove is sloping outwards, when it should be straight.

This is fairly common, and has a number of causes. Sometimes, it’s a simple case of wear and tear caused over the lifetime of the turbo, but it can also be caused by excessive wear in the thrust or journal bearings.

In addition, this kind of wear can also happen when carbonised oil builds up in the seal area, which then rubs at the groove during operation, wearing it away. Good oil management (checking and changing it regularly), using the right specification oil, and regularly changing your oil filter will help to prevent this.

Once a piston ring seal has become worn in this way, the best course of action is to replace it.

Turbine Shaft & Wheel – Worn Piston Ring Seal Groove (b)

Here, you can see a different example of wearing damage to a piston ring seal groove – in this case, the face on the inside of the groove has been worn away, so that it now has a lipped edge.

As in example (a), this kind of damage has a number of different causes, from general wear and tear, and excessive play/wearing in the journal and thrust bearings, to contaminated or carbonised oil getting into the piston ring seal area.

Over time, this wearing will become gradually worse, affecting both the efficiency and output of the turbocharger. Generally, it isn’t economically viable to repair wearing damage like this, and it’s much more cost effective to replace the affected piston ring seal.

In addition, it’s also important to identify the cause of the damage, so that it doesn’t happen again, which may mean making repairs or replacing the thrust and journal bearings.

 


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