ASE T1 Gasoline Engines (Medium/Heavy Truck) study guide
ASE T1 Gasoline Engines (Medium/Heavy Truck) · Work through your exam, one topic at a time.
ASE T1, Gasoline Engines (Medium/Heavy Truck), is one of the specialty credentials in the ASE Medium/Heavy Truck technician certification series. It is aimed at technicians who diagnose, service, and overhaul gasoline engines in trucks, buses, and commercial chassis rather than light-duty pickups. The ASE T1 Gasoline Engines (Medium/Heavy Truck) study guide has 10 sections and about 3,837 words.
01General Engine Diagnosis
General diagnosis is the umbrella skill: separating mechanical faults from fuel, ignition, air, and electronic faults before tearing anything apart. Know the three essentials for combustion (adequate compression, correct air/fuel mixture, properly timed ignition), the difference between a mechanical complaint (low compression, noise, blowby, vibration) and a performance complaint (misfire, low power, hard start, poor economy), and how to use a road test, a cylinder balance or power contribution test, a compression test (wet and dry), a cylinder leakage test, and a vacuum gauge reading to localize a fault.
423 words, about 2 min02Cylinder Head, Valve Train, and Camshaft Diagnosis and Repair
This domain covers the head casting, valves, springs, guides, seats, rocker arms, pushrods, lifters, and the camshaft. Know how to evaluate valve recession, valve stem-to-guide clearance, seat concentricity, spring free length and installed height, and camshaft lobe lift and base circle.
398 words, about 2 min03Cylinder Block, Crankshaft, and Bearings Diagnosis and Repair
This domain covers the block, cylinder bores, pistons, rings, crankshaft, main and rod bearings, and thrust bearing. Know how to measure cylinder taper, out-of-round, and ridge; how to check crankshaft journal size, taper, and out-of-round; how to read bearing wear patterns (fatigue, scoring, wiping, misassembly); and how to verify bearing clearance with plastigauge or micrometers.
389 words, about 2 min04Lubrication System Diagnosis and Repair
The lubrication system includes the oil pan, pickup, pump, relief valve, filter, galleries, and cooler. Know the difference between pressure and flow , how the relief valve regulates maximum pressure, how a bypass valve in the filter works, and how oil pressure behaves cold vs.
389 words, about 2 min05Cooling System Diagnosis and Repair
The cooling system includes the radiator, water pump, thermostat, fan and fan clutch, hoses, coolant, pressure cap, and the engine's coolant passages. Know how a pressure cap raises boiling point, how a thermostat regulates temperature, how a fan clutch engages, and how to test for combustion gases in coolant (block tester), pressure-test the system, and check for a restricted radiator or heater core.
353 words, about 2 min06Air Induction and Exhaust System Diagnosis and Repair
This domain covers the air cleaner, intake piping, turbocharger, charge-air cooler, intake and exhaust manifolds, EGR, and the exhaust system including the aftertreatment components on modern trucks. Know how to diagnose intake restrictions (air filter minder, vacuum gauge), boost leaks (low power, black smoke, hissing), turbo faults (shaft play, oil seals, wastegate or VGT actuator), exhaust restrictions (backpressure), and exhaust leaks (noise, soot tracking).
378 words, about 2 min07Fuel System Diagnosis and Repair
Gasoline fuel system diagnosis covers the tank, pump, filter, lines, pressure regulator, injectors, throttle body, and the electronic controls that meter fuel. Know how to test fuel pressure and volume, how to check for pressure drop (leaks, regulator), how to evaluate injector balance and spray pattern, and how to interpret fuel trims (short and long term) to separate vacuum leaks, fuel delivery faults, and sensor errors.
393 words, about 2 min08Ignition System Diagnosis and Repair
Gasoline ignition systems include the coil(s), distributor or coil-on-plug, spark plugs, wires, and the crank/cam sensors that trigger them. Know how to test for spark, how to read spark plug condition (fouling, gap, electrode wear, insulator color), how to evaluate coil and wire resistance, and how ignition timing is controlled.
382 words, about 2 min09Engine Electrical and Electronic Systems Diagnosis and Repair
This domain covers the battery, starting system, charging system, sensors, actuators, wiring, grounds, and the ECM/PCM that manages the engine. Know how to perform a voltage drop test, how to check battery state of charge and load, how to test the starter circuit, how to evaluate charging output, and how to use scan data and codes to guide diagnosis.
382 words, about 2 min10Engine Removal, Installation, and Rebuilding Procedures
This domain covers the procedures and precautions for removing, installing, and rebuilding an engine: labeling and organizing components, documenting timing marks, supporting the engine safely, disconnecting battery and fuel, capping lines, cleaning and inspecting parts, measuring wear, torque sequences and torque-to-yield fasteners, and proper break-in. Know the importance of cleanliness, correct fastener reuse, and verifying clearances during assembly.
350 words, about 2 min