Which statement is correct about excessive idling of a diesel engine?

• A. Excessive idling will cause cylinder walls to glaze and piston rings to stick
• B. Idling regularly for long periods causes piston rings to break
• C. Both statements are correct
• D. Neither statement is correct

Answer: (A)

Excessive idling affects lubrication and heat in a diesel engine. When the engine runs at idle for long periods, it operates at low load and-low temperature, so fuel may not burn completely and the lubricating oil film on the cylinder walls can be compromised. Diesel fuel can wash away some of that oil, leading to a glazed, hard, smooth surface on the cylinder walls. That glazing reduces the grip of the piston rings, causing them to stick or seize slightly and lose a good seal, which hurts compression and can raise oil consumption. Long idle is not typically the cause of piston rings breaking; ring breakage usually comes from severe overload, overheating, or persistent lubrication failure, not simply from idling. So the statement about glazing and ring sticking is the accurate one.