DTC DTC Preventive Maintenance and Service Intervals 2

Question 1

What should a diesel technician check when performing a coolant service to prevent liner cavitation erosion?

Accepted Answer

Supplemental coolant additive (SCA) concentration levels

Answer

SCA concentration must be maintained within specification to protect wet cylinder liners from cavitation erosion caused by pressure wave vibration.

Question 2

A diesel truck's serpentine belt shows glazing and minor cracking. What is the correct maintenance action?

Accepted Answer

Replace the belt before it fails, per manufacturer interval

Answer

Glazing and cracking indicate belt degradation; replacement before failure is the correct preventive action to avoid roadside breakdowns.

Question 3

How often should diesel fuel filters (primary and secondary) typically be replaced on a heavy-duty truck?

Accepted Answer

According to the manufacturer's maintenance schedule, often every 15,000–25,000 miles

Answer

Diesel fuel filter replacement intervals are specified by the manufacturer and typically fall between 15,000 and 25,000 miles to protect injectors from contamination.

Question 4

When lubricating fifth-wheel assemblies during preventive maintenance, which type of lubricant is typically recommended?

Accepted Answer

Multi-purpose chassis grease or fifth-wheel grease

Answer

Fifth-wheel assemblies require heavy-duty multi-purpose grease designed to withstand high loads and resist washout from road conditions.

Question 5

What is the main purpose of checking and adjusting diesel engine drive belt tension during preventive maintenance?

Accepted Answer

To prevent slippage that causes accessory failures and charging system problems

Answer

Correct belt tension prevents slippage on alternators, water pumps, and air compressors, which would result in component failure or undercharging.

DTC - Diesel Technician Certification Practice Test

DTC - Diesel Technician Certification Practice Test

DTC DTC Preventive Maintenance and Service Intervals 2