For machines: more complex design, higher probability of failure. In past, when it came to choosing between self-priming and turbocharged vehicles, main reasons for recommending were consistent quality, low failure rate, and cheap maintenance of self-priming engines. Based on past experience, turbocharged cars do have more failures than self-priming cars, and compared to self-priming cars, more turbocharged car failures are due to extra turbocharger.
"Lubrication" and "cooling" are two main causes of turbocharger failure
Before talking about how to avoid turbocharger breakdown, let's first understand structure and working principle of a turbocharger.
The turbocharger consists of a centrifugal compressor, a radial turbine and an intermediate housing. The turbocharger shaft is supported in intermediate housing by two floating bearings. The intermediate housing has oil channels for lubrication and cooling of bearings. are sealing devices to prevent oil from leaking into compressor or turbine, etc.
As for how it works, it uses exhaust gases emitted by engine itself to push turbine blades, and then drives suction blades on coaxial shaft, compressing air and forcing it into engine cylinder. to increase engine air intake, and then increase amount of fuel injection accordingly, thereby generating more power and greatly improving engine power and torque.
The operating temperature of turbocharger is between 900 and 1000°C, and speed reaches hundreds of thousands and even hundreds of thousands of revolutions per minute. Extremely high demands are placed on lubrication and dynamic balancing.
What conditions can lead to failure of "lubrication" and "cooling" of a turbocharger?
While blower has oil to lubricate and cool blower shaft and bearings, misuse will still cause blower to "lubricate" and "cool".
Intense driving after a cold start
The current car does not need to be warmed up on spot. After starting engine, car can run stably immediately, but it is strictly forbidden to drive a cold car vigorously. Because when engine is just started, if you immediately step on accelerator pedal to make engine run at high speed, turbocharger turbine will also run at high speed, and speed can reach more than 100,000 rpm. tear.
Shut down engine immediately after engine has been running at high rpm for a long time with a heavy load
The engine stops and turns off immediately after engine suddenly stops or at high speed. Due to inertia, turbine shaft still has to run at high speed (above 100,000 rpm) for a certain period of time. At this time, engine lubrication system has stopped working and no longer supplies power to supercharger. The oil supply, turbocharger shaft and floating bearings overheat due to lack of oil lubrication, resulting in combustion or premature wear of supercharger.
However, this applies to older turbocharged cars. The current turbocharged engine has a lag-cooling design and a separate cooling system is installed. After turning off engine, electronic water pump may continue to operate for some time. period of time. It will not stop until temperature of supercharger drops, which can effectively prevent high temperature of supercharger, such as turbo timer and other technologies. So for new cars purchased in recent years, this item can be ignored.
Press gas pedal before engine stops
Technology is ahead of experience, and experience must keep pace with times. Many older drivers find that depressing accelerator pedal before turning off engine is beneficial for next engine start. This method may be correct in age of carburetors, but for today's cars it is completely unnecessary, not only for fuel consumption, but also for old turbines. For models supercharged, this will cause premature wear of supercharger. As for reason, refer to previous article.
Using poor quality or poor quality oil
Because a turbocharged engine can reach a high temperature of almost 400°C in one minute at 2000rpm, which exceeds limit of mineral engine oil, so it has very high requirements for engine oil that ordinary oil cannot meet. mineral motor oil Use requirements, not to mention poor quality motor oil, it is easy to cause severe coking due to overheating, insufficient lubrication strength, and then cause abnormal wear of turbine bearing, resulting in damage to supercharger. If conditions permit, an engine oil with high shear and high temperature stability can be used.
Leak in intake pipe or damaged air filter
If intake piping is leaking or air filter is damaged, a lot of unfiltered air will pass through turbocharger. Such air contains a lot of dust and particles, which damage and wear blower intake wheel, thereby disturbing dynamic balance of impeller, resulting in abnormal blower noise or abnormal bearing wear; Also, if air filter blockage can also cause a power surge in supercharger.
Engine idling for a long time
The biggest problem with an engine idling for long periods of time is that it will result in poor heat dissipation from turbocharger, causing premature wear of turbocharger shaft and floating bearing due to overheating. The presence of water cooling, this problem mainly affects not very big. In principle, no one will let engine idle for a long time except for police cars and other working and special vehicles.