Free ASE Medium-Heavy Truck Diesel Engines (T2) Certification Test Practice Questions

Sample Practice Questions

Try these 10 sample questions from the ASE Medium-Heavy Truck Diesel Engines (T2) Certification Test practice bank. Each includes the answer and explanation. Continue with the interactive practice above to review the full question set.

1. 1A driver reports an intermittent loss of engine power, but the truck is operating normally in the shop. Which information should the technician use to establish the complaint before choosing further diagnosis?

   1. A. The driver interview and available past maintenance records
   2. B. A cleared fault-code list and a new road-test result only
   3. C. The repair invoice prepared after the engine is disassembled
   4. D. The replacement-parts list for an unrelated truck

   Answer: A

   Explanation: ASE directs technicians to "Verify the complaint, and road/dyno test vehicle; review driver/customer interview and past maintenance documents (if available); determine further diagnosis." The interview and available history help characterize an intermittent complaint before selecting further tests; clearing codes at this stage would discard useful information.

   Reference: Official ASE Medium/Heavy Truck Study Guide — T2 Task List, A. General Engine Diagnosis, task 1 (page 11)

2. 2A removed diesel cylinder head may have been distorted by overheating. Which inspection directly addresses whether its deck can be reused?

   1. A. Measure head thickness and inspect mating surfaces for warpage and finish
   2. B. Measure valve-seat contact and combustion-chamber volume
   3. C. Measure deck surface texture and oil-passage diameter
   4. D. Measure head-bolt stretch and replacement-gasket thickness

   Answer: A

   Explanation: ASE specifies, "Measure cylinder head thickness and check mating surfaces and related components for warpage and surface finish." The other measurements concern related hardware but leave the suspected head deck unchecked.

   Reference: Official ASE Medium/Heavy Truck Study Guide — T2 Task List, B. Cylinder Head and Valve Train, task 3 (page 12)

3. 3During inspection of a Detroit DD crankshaft, a crack is found in one counterweight. What service decision does Detroit's procedure require?

   1. A. Replace the crankshaft
   2. B. Polish the crack and reuse the crankshaft
   3. C. Increase main-bearing clearance
   4. D. Reuse it if the journal surfaces are smooth

   Answer: A

   Explanation: Detroit directs, "Inspect the crankshaft journals, flanges and counterweights for cracks. Replace the crankshaft if cracks are found." A crack in a counterweight meets the stated replacement condition; smooth journals do not cancel it.

   Reference: Crankshaft and Main/Connecting Rod Bearing Service Procedures — Inspection of the Crankshaft, step 4 (page 8)

4. 4At normal operating temperature, what is the lowest oil pressure Detroit permits at rated speed in its DD operator manual?

   1. A. 14 psi
   2. B. 35 psi
   3. C. 55 psi
   4. D. 75 psi

   Answer: C

   Explanation: Detroit says that at normal operating temperature oil pressure must not drop below "55 psi (380 kPa) at rated speed." The 14 psi value in the same section applies at idle, so 55 psi is the rated-speed minimum.

   Reference: DD Heavy Duty Platform Operators Manual — Chapter 5, Monitoring the Oil Pressure (page 56)

5. 5In a Detroit DD engine air system, which component cools compressed intake air after the turbocharger?

   1. A. Air-to-air charge cooler
   2. B. EGR cooler
   3. C. Diesel oxidation catalyst
   4. D. Engine coolant radiator

   Answer: A

   Explanation: "Outside air enters the engine through the air filter and is drawn to the turbocharger and then is compressed, and forced through the air-to-air charge cooler (heat exchanger) and is cooled." The charge cooler handles intake air; the EGR cooler handles recirculated exhaust, the DOC treats exhaust, and the radiator cools coolant.

   Reference: DD Heavy Duty Platform Operators Manual — Chapter 8, Air System, p. 86

6. 6In the Detroit DD three-filter fuel module, which element first removes relatively coarse particles down to about 100 microns?

   1. A. Prefilter
   2. B. Water separator/coalescer
   3. C. Final filter
   4. D. Two-filter coalescer/final element

   Answer: A

   Explanation: "The engine is equipped with a prefilter that filters down to 100 microns" The prefilter is the coarse filtration stage; the final filter is finer, while the sensor and valve have different functions.

   Reference: DD Heavy Duty Platform Operators Manual — Section 15.01.06, Monitoring the Three-Filter Fuel System Filters, p. 141

7. 7Before load-testing a battery in the Delco Remy heavy-duty starting-system procedure, what minimum state of charge should its open-circuit voltage establish?

   1. A. At least 50%
   2. B. At least 65%
   3. C. At least 80%
   4. D. Exactly 100%

   Answer: C

   Explanation: "measure the Open Circuit Voltage (OCV) of each battery to assure that they are at least 80% State-of-Charge (SOC)." The guide requires at least 80% SOC before testing, since a discharged battery can yield a false result.

   Reference: Heavy Duty Troubleshooting Guide: Starting and Charging System Testing — Inspect Batteries, p. 1

8. 8What event creates retarding action in a Jacobs compression-release engine brake when the engine is not fueling?

   1. A. Exhaust valves open near the top of compression to release compressed air
   2. B. An exhaust butterfly closes to create backpressure
   3. C. A hydraulic transmission retarder absorbs shaft energy
   4. D. Wheel service brakes create friction at their rotors

   Answer: A

   Explanation: "the Compression Release Brake opens the exhaust valves near the top of the compression stroke, releasing the highly compressed air through the exhaust system." Releasing compressed air prevents its expansion energy returning to the piston; the other mechanisms do not describe this brake.

   Reference: Jacobs Compression Release Engine Brake — How It Works, p. 2

9. 9After repairing the cause of a recorded diesel-engine fault code, which action checks whether the repair worked under operating conditions?

   1. A. Clear the code without running the engine
   2. B. Road-test or retest the vehicle and evaluate the result
   3. C. Replace the control module before checking the vehicle
   4. D. Ignore operational data because the fault was recorded

   Answer: B

   Explanation: ASE specifies "road test/retest to verify the repair; determine if further diagnosis is needed." A retest checks operation after the repair; code clearing alone cannot demonstrate that the fault has been corrected.

   Reference: Official ASE Medium/Heavy Truck Study Guide — T2 Task List, A. General Engine Diagnosis, task 17 (page 12)

10. 10After replacing a diesel cylinder head's injector sleeve and seal, which verification does the ASE T2 task list call for when applicable?

    1. A. Pressure-test the repair
    2. B. Measure injector-tip protrusion after installation
    3. C. Check injector calibration codes after installation
    4. D. Inspect the sleeve seating surface visually

    Answer: A

    Explanation: The ASE task says, "Inspect and/or replace injector sleeves and seals; pressure test to verify repair (if applicable)." Pressure testing is the stated verification when the engine design permits it; the other actions do not test the sleeve seal.

    Reference: Official ASE Medium/Heavy Truck Study Guide — T2 Task List, B. Cylinder Head and Valve Train, task 5 (page 12)