Checking and diagnostics of turbines of gasoline and diesel engines
HOW TURBINE WORKS
In short, the principle of operation of the turbine is as follows: to increase the power of the engine, more fuel must be supplied to it. This is not a problem, but more oxygen will also be needed in the mixture, but the cylinders will not be able to suck it in atmospheric mode. The turbocharger compresses air and pumps it into the cylinders under pressure - for this, blades are installed inside the turbine.
The difference between a diesel turbine and a gasoline turbine
It is clear that the compressor itself also needs to take energy for rotation somewhere, and rather big -. You can spend some of the engine power on this (systems with a driven supercharger, although rare, do exist), but it is better to use exhaust gas energy to drive the compressor. So the power is consumed quite a bit, 1.5-2%, and the efficiency of the power unit increases significantly.
Structurally, the turbocharger consists of two "snail" housings: "hot" (this, in fact, is the turbine that receives the exhaust gas flows) and "cold" (the compressor that pumps air into the intake manifold). Inside them are two wheels with blades, rigidly connected to each other by an axle-rotor, which is also in its housing, where bearings are installed and a lubrication and cooling system is provided.
Both a single turbocharger and a system of two or even several turbines can be installed on engines, with different installation schemes:
parallel, when each turbine is responsible for its part of the cylinders, working either on a direct or cross principle;
sequential (sequential), when the turbines are installed one by one, the first one works at low engine speeds, the second - at high ones. In the biturbo system, these are turbines of different diameters (the second one is larger), and in the twin-turbo system they are the same.
Dual turbocharging allows you to increase power in all rev ranges, to avoid the so-called. turbo pit. In addition, turbines with variable geometry have recently appeared.
WEAK POINTS OF THE TURBOCOMPRESSOR
Engine turbine: malfunctions, check, resource and operation
The operating conditions of the turbine cannot be called sparing. The speed of rotation of the compressor shaft reaches 200,000 rpm, and the temperature of the exhaust gases reaches 1000 ° C for gasoline engines and "only" 750-850 for diesel engines. This causes high requirements for the materials from which the assembly components are made. For example, the bodies of "snails" are cast from high-strength heat-resistant cast iron. All parts of the turbocharger are manufactured and fitted with precision precision, excluding minimal backlash and gaps.
Meanwhile, only a small part of turbine breakdowns (5-10%) occurs from the natural wear of the unit, “from old age”. The cause of most malfunctions is improper operation:
Use of engine oil with unsuitable characteristics. The turbine lubrication system is also a cooling system (even if it works in parallel with liquid cooling), so the heat transfer of the oil is very important.
Neglect of oil change service intervals. In addition to deteriorating cooling properties, old oil contains a large amount of wear particles that destroy bearings and the compressor rotor.
Oil starvation, which can be caused by either a low level of lubrication or a malfunction of the oil pump or filter valve.
Ingress of foreign objects through the air channel (with a clogged or damaged filter) or from the exhaust system (damage to the catalyst, mufflers, piston group, etc.).
Illiterate chip tuning, leading to too fast rotation of the turbine.
SIGNS OF A FAILURE TURBINE
As a rule, a turbocharger rarely fails instantly. The first symptoms of malfunctions in the turbine manifest themselves even when it is almost fully operational. Signs of "dying" of the turbine will be:
extraneous noise (hum or whistle) from the turbocharger;
increased waste / oil consumption;
gray or black exhaust;
oil smudges (increased fogging) from under the seals of pipes, clamps;
reduction in engine power;
an increase in temperature (overheating).
It should be noted that in some cases the cessation of operation of the turbine is not a consequence of its malfunction - for example, if the vacuum pump fails or if there is a malfunction in the electronic control system.
HOW TO CHECK THE TURBINE YOURSELF
How to check a turbine on a diesel engine: methods for diagnosing and troubleshooting
You can check the performance and wear of the turbocharger yourself without removing the assembly from the car. This will help when diagnosing problems on your own car, and when buying a used car equipped with a turbocharger.
Inspect the turbine pipes, first of all - the one that connects the compressor to the intake manifold or intercooler, disconnect it. Only slight oil fogging is allowed, a copious amount of oil will indicate turbine or engine wear.
Inspect the turbine wheel impeller. The blades must be without damage, nicks, have the correct geometry.
Check turbine shaft play: axial (forward
ed-back) and radial (left-right). In the first case, it should not be at all (maximum 0.5 mm), in the second, a maximum of 1 mm is allowed.
Inspect the entire line: nozzles, flanges, turbine and compressor housings for cracks.
You can also check the performance of the turbine with the engine running. To do this, you need to hand over the pipe going from the supercharger to the engine or intercooler, and give it gas (press the accelerator pedal). If at the same time it is felt that the pipe is inflating, then the turbine is conditionally working.
RECOMMENDATIONS
Of course, such checks can only give a superficial idea of the performance of a turbocharger. For high-quality diagnostics, it is better to turn to professionals - for example, at the service station of the Wilgood smart car service network. Moreover, this applies to the repair of the turbine: it is impossible to sort out, adjust and balance the parts of the turbocharger in garage conditions, in the absence of experience, with high quality.
To extend the life of the turbine, follow simple rules:
use only those engine oils recommended by the car manufacturer;
change oil, filters (including air filters) on a new car in time, with an increase in mileage, reduce the service interval by at least half;
do not turn off the engine immediately after stopping, let it run for 1-1.5 minutes (you can install a turbo timer);
always warm up a turbocharged car for at least 1-2 minutes before driving;
do not exceed engine speed and do not abuse chip tuning.
And may the force and power of the turbine be with you!