Turbochargers are built to last the lifetime of a vehicle. Car manufacturers extensively test the uniquely matched turbocharger and engine together, to avoid any unexpected failures. However, lack of maintenance, hazardous driving or a single component failure, could have a harmful influence on your turbocharger.
1. FOREIGN OBJECT DAMAGE
Turbochargers move at rotational speeds higher than 200,000 RPM (over 3300 rotations per second!). You can imagine that at those speeds, damage accumulates incredibly quickly. Since the tips of the blades move at a speed of around 2000 km/h, any object that enters the turbocharger, even as small as grains of sand, can partially or completely damage it.
TIP! Regularly check the condition of your air filter!
This is caused from the exhaust gasses being bypassed in a W/G (wastegate) turbo or not enough pressure build up in a VG (variable geometry) turbo and therefore not being able to deliver the desired boost to the engine. In this case the car will not accelerate as quickly as you are used to. W/G or VG systems in a turbocharger are there to control the amount of boost delivered to the engine. If this system fails, the engine will detect it is getting too much boost. To protect itself, the engine will turn on the light on the dashboard and might also go into limp mode. An important thing to note is that a W/G system has a tendency to get stuck due to corrosion and a VG system has a tendency to get stuck due to contamination.
TIP! Use the car regularly. This will not give corrosion or contamination a chance to settle and increase the friction in the system or get it stuck completely.
Use complete engine range. This has two benefits: Firstly, if you use the full range of the engine's RPM and power you also use the full range of the W/G or VG system as well. Secondly, the heat generated at higher engine loads can help to burn away part of the contamination that might have built up on the system.
Of course, if you do these things make sure that the engine is on operating temperature and make sure that you don’t give the car a hot shutdown (see Heat Soak below for more information).
3. BEARING WEAR
The most sensitive components of a turbocharger are its bearings. With tolerances smaller than the thickness of your hair, even the slightest imperfection can cause it to fail over lifetime. There are 2 types of bearings in a turbocharger: a radial bearing (left) and an axial bearing (right). The radial bearing supports the side-to-side movement of the shaft of the turbocharger. The axial bearing supports the axial movement of the shaft. Both bearings are very dependent of the oil supplied to them. If the oil quality (particles in the oil) is bad or not enough oil is supplied, failure of the turbocharger can happen within seconds.
TIP! Always stick to the prescribed oil change intervals.
A turbocharger forces extra air into the engine to be able to burn more fuel. In the industry, the compressed air is called boost. If you want to accelerate, boost is necessary. There are also scenarios when the turbocharger is still providing boost, but the engine does not need it. For example, when you shift gears. At this point the throttle valve closes. The turbocharger is however still rotating very quickly and is still building up boost. Due to the closed throttle valve this boost cannot be delivered to the engine anymore and the boosted air accumulates in the inlet manifold. When the amount of accumulated air becomes too much, it will start flowing backwards into the wrong direction over the compressor wheel. After this “release” the compressor wheel will again build up boost and the cycle repeats. This pulsating air flow is called surge and can be quite violent and puts a lot of stress on the bearing system, the shaft and the compressor wheel. Prolonged exposure to surge can lead to catastrophic failure of the turbocharger.
TIP! There is unfortunately not much you can do to prevent surge. If you believe that your engine is running irregularly, please take it to a specialist.
5. HEAT SOAK
The fact that a turbocharger works in a very hot environment already poses challenges of its own during operation. Sufficient cooling is needed to keep everything (primarily the bearings) functioning correctly. Something inevitable during driving is eventually turning off the engine. Sometimes this occurs after the engine has been working hard with all the components being very hot. These so called “hot shutdowns” (sudden engine shutdown after period of high engine load) pose another potential risk for failure of the turbocharger. During operation there will be plenty of oil and coolant going through the turbocharger to keep all temperatures within the designed limits. However, when the engine is shut off quickly after a high engine load situation the flow of cool oil and coolant stops. This will cause the remaining oil in the turbocharger to “soak” the heat increasing the likelihood of oil coking which means that the oil will burn and leave particles in the bearing system and on the shaft. This will damage the bearings, and the cartridge could become noisy due to this.
TIP! If you have an older car with a turbocharger, it will help as a driver to drive less aggressively (no high loads on the engine) for the last few minutes before shutting down the engine to lower the risk of oil coking due to heat soak.