DTC DTC Diesel Engine Lubrication Systems

Question 1

What is the primary function of the engine oil pump in a diesel engine's lubrication system?

Accepted Answer

To circulate pressurized oil to all engine bearings, journals, and moving components

Answer

To cool the turbocharger intercooler

Answer

To filter contaminants from the fuel

Answer

To pressurize the fuel rail

Question 2

A diesel engine's oil pressure warning light illuminates at idle. What is the FIRST diagnostic step a technician should take?

Accepted Answer

Verify actual oil pressure with a mechanical gauge to confirm the reading is accurate

Answer

Immediately replace the oil pump

Answer

Add oil without checking the current level

Answer

Replace the oil pressure sending unit

Question 3

What does a diesel engine's oil cooler primarily do?

Accepted Answer

Removes excess heat from the engine oil to maintain proper viscosity and protect components

Answer

Heats engine oil for cold starts

Answer

Filters metal particles from the oil

Answer

Pressurizes the crankcase

Question 4

Which viscosity grade of engine oil is most commonly specified for heavy-duty diesel engines in warm climates?

Accepted Answer

SAE 15W-40

Answer

SAE 5W-20

Answer

SAE 0W-16

Answer

SAE 50 straight weight

Question 5

What is the purpose of the oil pressure relief valve in a diesel engine lubrication system?

Accepted Answer

To limit maximum oil pressure and protect bearings and seals from excessive pressure

Answer

To increase pressure during cold starts

Answer

To remove water from the oil

Answer

To regulate fuel pressure

Question 6

When should a diesel technician use an oil analysis service as part of a preventive maintenance program?

Accepted Answer

Regularly at defined intervals to detect internal wear metals, coolant contamination, and oil degradation before failure occurs

Answer

Only after an engine rebuild

Answer

Only when oil pressure drops below spec

Answer

Only if the driver reports a noise