The crankcases of many diesel engines are...

Question 1 / 270705eccefa1bacbc34ba4d47442

Question 1 of 270705eccefa1bacbc34ba4d47442

The crankcases of many diesel engines are kept under a slight vacuum to __________.

Question 1 of 27070

The crankcases of many diesel engines are kept under a slight vacuum to __________.

🔍 Key Concepts

• Diesel engine crankcase purpose and what is inside it (lubricating oil, vapors, blow‑by gases) • What conditions are needed for a crankcase explosion (fuel/oil mist + air + ignition source) • Effect of keeping a slight vacuum versus pressure inside a closed space containing oil mist

💭 Think About

• Think about which choice directly relates to safety inside an enclosed space containing oil vapor and hot parts. • Ask yourself: does a small vacuum significantly change fuel economy or air charge velocity, or is it mainly about controlling vapors and leakage? • Consider what might happen if pressure built up in the crankcase instead of being held slightly below atmospheric pressure.

✅ Before You Answer

• Identify which option is most clearly related to preventing accumulation of flammable vapors. • Consider whether air charge velocity is controlled by crankcase conditions or by the intake/compressor side of the engine. • Check which benefits are primary design reasons for crankcase vacuum systems, and which sound more like secondary or unlikely side effects.

Question 1 of 27070

The crankcases of many diesel engines are kept under a slight vacuum to __________.

improve fuel economy

increase the air charge velocity

reduce the risk of explosion

all of the above