(A9) Light Vehicle Diesel Engines

Animations by ASE Content Area. Includes Tasks and Priority levels.

A: General (click to expand)

Adjust Valve Clearance (Task 1) (Priority 3)


Task 1: Research vehicle service information, including fluid type, vehicle service history, service precautions, and technical service bulletins.

Task 2: Inspect level and condition of fuel, oil, diesel exhaust fluid (DEF), and coolant.

Task 3: Inspect engine assembly for fuel, oil, coolant, air, and other leaks.

Task 4: Check engine operation (starting and running) including: noise, vibration, smoke, etc.

Task 5: Use appropriate electronic service tool(s) and procedures to check, record, and clear diagnostic codes; check and record trip/operational data; reset maintenance monitor (if applicable); interpret digital multimeter (DMM) readings.

Task 6: Identify system components, configurations, and types of the following: cylinder head(s), valve train, engine block, engine lubrication, engine cooling, air induction, exhaust, fuel, and engine braking.

B: Cylinder Head and Valve Train (click to expand)

Adjust Valve Clearance (Task 1) (Priority 3)


Task 1: Inspect electronic wiring harness and brackets for wear, bending, cracks, and looseness.

C: Engine Block (click to expand)

Adjust Valve Clearance (Task 1) (Priority 3)


Task 1: Inspect crankshaft vibration damper; inspect engine mounts.

D: Cooling System (click to expand)

Adjust Valve Clearance (Task 1) (Priority 3)


Task 1: Check engine coolant type, level, condition, and test coolant for freeze protection and additive package concentration.

Task 2: Verify coolant temperature; check operation of temperature and level sensors, gauge, and/or sending unit.

Task 3: Inspect and reinstall/replace pulleys, tensioners and drive belts; adjust drive belts and check alignment.

Task 4: Recover coolant, flush, and refill with recommended coolant/additive package; bleed cooling system.

Task 5: Inspect coolant conditioner/filter assembly for leaks; inspect valves, lines, and fittings; replace as needed.

Task 6: Inspect water pump, hoses, and clamps.

Task 7: Inspect, and pressure test cooling system(s); pressure test cap, tank(s), and recovery systems; inspect radiator and mountings.

Task 8: Inspect thermostatic cooling fan system (hydraulic, pneumatic, and electronic) and fan shroud.

Task 9: Identify engine block heater(s).

E: Air Induction and Exhaust Systems (click to expand)

Adjust Valve Clearance (Task 1) (Priority 3)


Task 1: Inspect turbocharger(s), wastegate(s), and piping systems.

Task 2: Check air induction system including: cooler assembly, piping, hoses, clamps, and mountings; replace air filter as needed; reset restriction indicator (if applicable).

Task 3: Inspect intake manifold, gaskets, and connections.

Task 4: Inspect engine exhaust system, exhaust gas recirculation (EGR) system, and exhaust aftertreatment system for leaks, mounting, proper routing, and damaged or missing components.

Task 5: Inspect crankcase ventilation system; service as needed.

F: Fuel System (click to expand)

Adjust Valve Clearance (Task 1) (Priority 3)


Task 1: Check fuel level and condition.

Task 2: Inspect fuel tanks, vents, caps, mounts, valves, screens, crossover system, hoses, lines, and fittings. 

Task 3: Inspect low pressure fuel system components (fuel pump, pump drives, screens, fuel/water separators/indicators, hoses, lines, filters, heaters, coolers, ECM cooling plates, check valves, pressure regulator valves, restrictive fittings, and mounting hardware). 

Task 4: Replace fuel filter; prime and bleed fuel system.

Task 5: Inspect high pressure fuel system components (fuel pump, pump drives, hoses, injection lines, filters, hold-downs, fittings, seals, and mounting hardware). 

G: Engine Brakes (click to expand)

Adjust Valve Clearance (Task 1) (Priority 3)


Task 1: Inspect engine compression and/or exhaust brake housing, valves, seals, lines, and fittings.