Labyrinth: the basic idea behind the new three-section crankcase designed for the Audi A4.
Here is a cross section of an oil cooler (2), in which engine oil is cooled, in an engine with a displacement of 1.6 liters. All Audi engines are equipped with such an oil cooler. The cooled oil is supplied through the connection unit «1» - and the next node - along the oil cooler and cools the engine oil due to the radiator plates visible in this photo. Oil is pumped through the oil filter (3).
Oil pump
At full throttle, the oil pump pumps about 30 liters of oil per minute through the engine:
- In a four-cylinder engine, the intermediate shaft drives the shaft, the bottom of which drives the oil pump.
- In a 16-cylinder engine, the oil pump is mounted on the crankshaft forward in the direction of travel.
- The way the pumps work in our Audi engines is also different.
- The four-cylinder engine has a gear oil pump. Two gears of the same size meshing with each other simply scoop oil from the suction side to the pressure side.
- The six-cylinder engine is lubricated by an Eaton rotary oil pump. In this case, the gear with external teeth is placed in the gear with internal teeth (these are both rotors). By shaping and eccentrically arranging the inner rotor, an effect is achieved in which, when both gears rotate together, new spaces of reduced pressure are constantly created. Thus, the engine oil is sucked in. From the rotating gears, the oil is squeezed out to the outlet side of the pump and from there into the lubrication channels.
Oil temperature
For good «well-being» engine oil temperature is critical. This information can only be obtained by the Audi driver from the built-in additional devices. Let's compare for interest the engine temperature at the oil filter flange or at the oil pump; where the temperature is the lowest. On the contrary, the oil temperature reaches 300°C on the piston rings.
If you drive a car with an oil thermometer: Audi considers 145°C in the crankcase to be the maximum allowable temperature. Although the condition for this is the presence of high-quality oil in accordance with the instructions.
Too low oil temperature is also harmful for the engine. In this case, the oil has not yet reached its full lubricity. If possible, after starting a cold engine, do not increase the speed above 3500 rpm until the oil has warmed up to about 60°C. The starting point is that oil takes twice as long as coolant to reach its operating temperature.
Oil pressure
If your Audi A4 has an oil pressure sensor built into it, or if you can connect an oil pressure sensor to the engine in the workshop instead of an oil pressure switch, then you can control its pressure yourself within the accuracy of the gauge. Test condition: oil temperature 80°C. The following indicators should be obtained:
- Oil pressure at idle: 1–2.5 bar.
- Oil pressure at 3000 rpm: 3-5 bar.
Oil pressure is also well controlled without a gauge in Audi. You will learn more about this in the chapter Tools and devices.
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