What is the negative pressure of an Audi engine in bar?
2 Answers
The normal value for crankcase negative pressure is -350mbar. Ventilation methods: Crankcase ventilation methods include natural ventilation and forced ventilation. To prevent excessive crankcase pressure, extend the service life of engine oil, reduce component wear and corrosion, and prevent engine oil leakage, crankcase ventilation must be implemented. Modern gasoline engines commonly use forced crankcase ventilation, also known as the PCV system. Characteristics of automotive crankcases: The upper crankcase is cast integrally with the cylinder block, while the lower crankcase is used to store lubricating oil and seal the upper crankcase, hence it is also called the oil pan. The oil pan bears minimal stress and is generally made of stamped thin steel plate, with its shape determined by the engine's overall layout and oil capacity. The oil pan is equipped with an oil stabilizing baffle to prevent excessive oil surface fluctuations when the vehicle is jolted.
The negative pressure value of an Audi engine at idle generally ranges between 0.25 and 0.35 bar, indicating the level of vacuum in the intake manifold. Negative pressure is a critical indicator of normal engine operation, affecting multiple systems such as the vacuum-assisted braking. If the value is too low, it may cause the brake pedal to become stiff, increasing safety risks. Common causes include leaks in the intake system, such as aging hoses or damaged gaskets, or wear and tear of engine components. During inspections, a vacuum gauge can be connected to the manifold port for direct measurement. While driving, if you notice engine shaking or sluggish acceleration, it might be related to abnormal negative pressure. Regular maintenance, such as replacing the air filter or checking seals, is recommended to maintain stable values around 0.3 bar and prevent sudden failures. Audi engines are typically designed with precision, resulting in minimal negative pressure fluctuations, but it's still important to watch for warning signs to prevent minor issues from escalating.
