🔍 Key Concepts

• Blow-by in diesel engines refers to combustion gases escaping from the combustion chamber into the crankcase. • The path of these gases is usually between the piston and the cylinder wall, where the piston rings are located. • Different rings (compression, oil control/scraper) have different primary purposes in sealing and oil control.

💭 Think About

• Think about which components are directly responsible for sealing the high-pressure combustion gases at the top of the piston stroke. • Ask yourself: which rings are designed mainly to keep compression in the cylinder, and which are mainly for controlling lubricating oil on the cylinder walls? • Consider which answer choice best describes the complete path through which combustion gases can leak down into the crankcase.

✅ Before You Answer

• Identify the ring(s) whose main job is to hold back combustion pressure at the top of the cylinder. • Confirm which ring(s) are primarily oil control/scraper rings, not compression sealing rings. • Make sure the option you select represents all the ring types involved in sealing combustion gases, not just oil control or just mechanical support.