A turbocharger makes use of the used exhaust gases and forces it through the turbo that acts as an air compressor. The additional air produced from the turbo gets pushed into the cylinder that allows for more fuel to be burnt.
A turbo in a car is one method to increase car horsepower and overall efficiency. Due to environmental issues, large engine cars are being replaced with smaller engine turbocharged cars that are able to match the performance.
You don’t have to stop at one turbocharger, many performance cars are twin-turbocharged and better yet, the Bugatti Veyron has 4 turbos! However, does this mean more trouble?
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Bad Turbo Symptoms
Turbos are a great way to improve the performance of yours car, however there are many common turbo problems that you should be wary off before buying a turbocharged car.
- Loud Siren Noise. Turbocharged cars do make good noises such as spooling or a blow off valve noise but there are also bad noises. If you here a “police siren” type of noise that is gradually getting louder, this is a bad sign. It may be a loose pipe or the blades failing within the turbo.
- Poor Acceleration. If you are not feeling the usual power when accelerating, the first thing to check would be the turbo.
- Excessive Exhaust Smoke. You can tell a lot from exhaust smoke and a faulty turbo will cause excessive exhaust smoke of a range of colors.
- Increased Oil Consumption. If you are noticing your car using more oil, this could be a sign that your turbo is leaking oil and leaking into the manifold.
- Engine Management Light. The majority of modern cars with a trip computer will trigger the engine management light, which will usually be matched with another symptom above.
Before you point all fingers at your turbocharger, you will want to ensure that the car has good all round health. For example, a faulty EGR can cause excessive exhaust smoke and poor acceleration if blocked. Likewise when you have a blocked DPF, it will often cause the car to go into limp mode or whilst going through regeneration of the DPF, there could be excessive smoke.
Causes of Turbo Failure
Its important to know the reason why the turbo failed because you may fit a new or refurbished turbo that could fail through an underlying fault. Below are some of the main reasons for turbos to fail:
- Cracks and Poor Seals. A turbo uses forced gases to push back into the cylinders and if there is a crack or faulty seal, some of that gas will be lost. Pipes leading to the turbo often crack overtime and is fairly common (see below photo).
- Old Age or Heavy Use. As with any other car component, everything has a life span and the turbocharger is no exception. If you have driven over 100,000 miles on the factory turbo and suffering turbo problems, it probably needs replacing.
- Poor Oil Quality Forming Carbon Deposits. The oil should be changed at every service and as regularly as possible using the best synthetic motor oil where possible. Lack of oil changes can result in a build up of carbon deposits entering the turbocharger.
- Objects Entering the Turbo. Dust, stones, leaves and other small objects can enter into the turbo via the compressor or turbine inlets. This will cause damage to the blades inside the turbo and eventually wear down the turbo until it breaks.
- Not Letting the Turbo Cool Down. After a long drive or aggressive driving, you should never switch the engine straight off. Always let the engine idle for a minute or so. Otherwise the turbo will be deprived of fresh oil as its spooling down. Overtime this will cause unwanted stress to the turbocharger.
Even the smallest cracks in one of the pipes coming too and from the turbo can cause issues. Below is an intercooler pipe that was cracked (bottom pipe) on one of my cars, which caused very poor performance from the turbocharger.
Reconditioned or New Turbocharger
If you have diagnosed that your turbo has broken, you will be thrown into the whether you should invest in a new or reconditioned turbo. Both will fix the car and be backed up with warranties in case the turbo breaks again, but whats the best solution?
A brand new turbocharger can be bought fairly cheaply and fitted by yourself or a mechanic. As its new, you will have peace of mind that it should last another 100,000 miles, however you will be paying more than a reconditioned turbocharger.
A reconditioned turbo is where a specialist will strip the turbocharger to each individual turbo part such as the compressor housing and wheel, turbine housing and wheel, bearings and more. Worn parts will be replaced and the turbo bearings and seals will be replaced with new parts.
A rebuilt turbo can cost around 400-500$, whereas a new turbo may cost double that. Choosing between the two is dependent on your personal preference and of course your budget.
Noises from the Turbocharger
Other than a loss of power, the noise in which a turbo will make will give you a strong indication of its health. A turbocharger will make good and bad noises but with regards to the bad noise, it is best described as a police siren.
Once your turbo has reached this stage, you should really be looking for a replacement. The police siren noise is usually caused by damaged turbines or missing blades. If you are wondering what the police siren noise from a turbocharger sounds likes, view the below video.
Blow Off Valve
A blow off valve (often called dump valve) is located between the turbo compressor and the throttle. As the turbo is on boost, the intake system will become filled with pressurized air from the turbo compressor. Blow off valves will release this pressurized air and makes a desirable hissing noise.
There are various forms of blow off valves available for turbocharged vehicles. However, if you do not own a turbo car, you can achieve the blow off valve noise via an electronic system, which creates a fake turbo noise. Some car owners even opt for an exhaust turbo whistle that attaches to the end of your exhaust tips.