Diesel Technician Practice Test

These questions are part of the practice quiz. Start practicing

• What is the most likely cause of excessively high oil pressure?
• What is an advantage of pneumatic tools over electric tools in a truck service shop?
• What is the maximum lubrication oil temperature that should not exceed?
• What is the most likely cause of excessively low oil pressure?
• Who is correct regarding the slow warm-up of a late-model diesel engine?
• What is true about coolant flowing from a low-flow radiator?
• What is the primary goal of using low ash content oil for catalyzed DPFs?
• When a cylinder head bolt torque specification requires that the fastener is first torqued, then turned through a further set number of degrees, what is this method known as?
• Which component turns at the same speed as the crankshaft in a two-cycle engine?
• What is the primary purpose of a heavy, flat steel plate bolted to the oil pan rails?
• Which method is primarily used to clean ash from a DPF?
• Regarding a coolant leak from a Detroit S60 engine, who is correct about the source of the leak?
• Regarding rear gear trains, which technician is correct?
• Who is correct concerning the type of oil needed to prevent damage to exhaust aftertreatment systems?
• What does Technician A say about the function of the waste gate or turbine bypass valve?
• What is the preferred tool to check the inlet restriction of a dry air filter?
• What is the purpose of a diesel particulate filter (DPF)?
• Who believes that tracking oil consumption is the best diagnostic approach for high oil consumption complaints?
• Which part of the engine is primarily affected when discussing coolant leaks from the cylinder block?
• How can insufficient liner protrusion be corrected?
• What type of combustion chamber is predominantly used in medium- and heavy-duty diesel engines?
• What stores kinetic energy during the power strokes in an engine?
• What is the correct method for measuring liner protrusion according to Technician B?
• Air to Air chargers provide all of the following, EXCEPT:
• What could be a consequence of a defective vibration dampener?
• When checking the engine oil on a cold engine, what should you do?
• Which component is primarily responsible for preventing cooling system boil over?
• What is the consequence of silicate drop-out in cooling systems?
• Who is correct regarding the effects of a defective vibration dampener?
• What is a typical maximum specified inlet restriction for a turbocharged diesel air filter?
• Which engine component assists in the expulsion of end gas during valve overlap?
• Who is correct about the role of turbochargers in commercial diesel engines?
• After the oil and filter change on a diesel engine, the oil warning light remains on. Who is correct in diagnosing the issue, Technician A or Technician B?
• What is the role of main bearing caps in an engine?
• Does the water manifold collect coolant from the engine block and direct it to the cylinder head?
• How should a coolant recovery tank be mounted for effective operation?
• Who accurately describes the effect of oil type on ash plugging in a diesel particulate filter?
• Who suggests that an abnormal amount of ash plugging in a diesel particulate filter could be due to oil incompatibility with a DPF?
• What does Technician B claim about anti-freeze?
• What is wet liner cavitation caused by?
• According to Technician A, what is the effect of pressurizing the cooling system?
• In a naturally aspirated engine, which technician is right: Technician A claims a pressure difference forces air into the cylinder, while Technician B says piston movement creates this pressure difference?
• Studs are commonly used to attach a throttle body to which manifold?
• When is it necessary to re-torque the exhaust manifold bolts according to Technician B?
• What is one key maintenance step for rubber hoses in the intake system?
• If an upper radiator hose collapses after an engine cools, what is the likely cause?
• Why are split pins used in conjunction with castellated nuts?
• What is the primary function of blowers?
• Why are cartridge filters preferred over spin-on filters?
• During which part of the cycle does cylinder scavenging occur, according to Technician B?
• Which technician is correct about torque specifications for vehicle bolts?
• What is one method not used to clean a DPF?
• Which strategy is most likely to be used for the passive regeneration of a catalyzed DPF?
• What should be checked when there is a concern about the oil clearance of a crankshaft and main bearing?
• Which technician recommends backward flushing an oil cooler after repairing an engine with damaged bearings?
• What does Technician A assert about the time it takes for diesel engine oil to blacken?
• What material is noted for making the lightest, strongest, and quietest engine blocks?
• Should you prime the oil filter before installation when changing the engine oil filter?
• If engine oil appears milky white, what could be the potential issue?
• When checking engine oil pressure on a cold engine, what can you expect regarding the oil pressure values?
• What does the prefix "milli" signify in measurements?
• Which strategy is commonly used to actively regenerate a catalyzed DPF?
• Which tool does Technician B say can cut thin sheet metal?
• What is the recommended grit stone rating for glazing-busting a liner with a hone?
• Who is correct regarding the longevity of synthetic oils compared to conventional oil?
• What result occurs when intake valve adjustments are set too tight?
• Can a restrictions gauge effectively monitor air filter blockage?
• Which instrument is utilized to accurately check antifreeze protection in a heavy-duty diesel engine?
• What should be concluded if rod bearing inserts protrude slightly above the margin of the bearing cap?
• Who is correct regarding the function of mid-stop liners and half-stop liners?
• What should be checked for looseness and damage in the intake system?
• How many times does any one piston change direction during one complete diesel cycle?
• What component in a diesel engine contributes significantly to the compression ignition process?
• Why might technicians discuss the type of liner used in engine manufacturing?
• What could be possible causes of high oil pressure?
• What role does an intensifier play in the coolant system of a diesel engine?
• Can pyrometers be used to test psi in the exhaust pipe or turbocharger?
• Why is the fan clutch popular on diesel engines?
• Which tool should be used to torque line nuts?
• Which crankshaft hardening technique achieves the deepest hardening effect?
• Which of the following components can be affected by cavitation erosion?
• How does a clean air cleaner affect engine performance?
• What is the position of the engine valves during the compression stroke?
• Which type of air filter is most commonly used in on-highway diesel engines?
• Which type of engine block is most likely to have coolant contamination of the crankcase due to a leaking liner O-ring?
• What is used to raise coolant circuit pressure in a diesel engine?
• To convert pound/feet to pound/inch, what multiplier is used?
• Which components are found in the exhaust of diesel engines?
• Which statement is true about particulate matter?
• The "15W" in 15W-40 engine oil stands for which of the following?
• What characterizes a naturally aspirated engine?
• Which storage medium holds the most repair information in the least amount of space?
• During which stroke of a four-stroke internal combustion engine does air charge the cylinder?
• Who is correct regarding the reuse of an exhaust manifold gasket?
• During the filling of a coolant system, who is correct regarding the handling of the engine venting petcock and the after-cooler petcock?
• What tool is specifically required to cut internal threads in a hole?
• Who is correct regarding viscosity index improvers?
• In terms of air-fuel mixture, what can result from a malfunctioning fuel injector?
• When does scavenging occur in the four-stroke diesel cycle?
• Which of the following is NOT found in heavy duty diesel engines?
• Which of the following best describes a consequence of a lower cooling efficiency?
• What does Technician A say is indicated by oil leaking out of the exhaust ports?
• What is a function of the air to air charger in an intake system?
• Which type of pliers is most suitable for intricate electrical work?
• What does a dial indicator measure in engine components?
• What is the minimum efficiency rating for heavy-duty diesel air filters?
• What is the purpose of bolster bolts or tie bolts in an engine block?
• Chromates, borates, and nitrites are types of what?
• What part of the exhaust system is necessary for turbocharger functionality?
• Which feature is characteristic of a ladder-frame engine block?
• Who is correct regarding the effects of long valve overlap periods?
• When checking a cylinder block deck for warpage with a thickness gauge and straight edge, what would be a typical maximum specification?
• What happens to engine oil when it becomes hotter?
• What type of socket must be used when utilizing an air gun to drive a socket?
• Who is correct about checking lifting equipment before use?
• When reverse flushing a cooling system, which technician is correct about the removal of components?
• What is the purpose of frost plugs or core plugs in engine blocks?
• What process delivers improved fuel economy in modern diesel engines?
• What type of oil is required for catalyzed DPFs?
• Which type of oil cooler is usually located within the engine or crankcase?
• In a cylinder head bolt torque sequence, which bolts should be torqued last?
• The presence of cavitation on a replaceable cylinder liner is most likely caused by what?
• If the DPF warning light is flashing along with the red shut-down lamp, what does Technician A suggest? Why does Technician B disagree?
• What should be inspected in the intake system?
• Who is correct regarding the use of seals and gaskets?
• How often should the fuel filter be replaced in diesel engines under normal operation conditions?
• What is the most recent diesel engine oil classification?
• What does cooling system pressurization enable according to Technician A?
• An engine that operates at too low a temperature tends to do what?
• What is the reason for using template torque when fastening cylinder head bolts?
• At what coolant temperature do most typical thermostat valves remain closed?
• Which component is primarily at risk in Class C fires?
• Who is correct regarding the cause of damage to a disintegrated DPF filter?
• What is a negative aspect of aftercoolers compared to intercoolers?
• What factors determine the replacement or service interval for an air filter?
• Who is correct regarding the source of a diesel engine's high torque output?
• What is considered a sign of improper antifreeze concentration?
• Which technician is correct regarding the problems with long-life anti-freeze?
• Which of the following is crucial to prevent overheating in diesel engines?
• Through how many thimble rotations must a standard micrometer be turned to make the spindle move exactly 1/4 inch?
• What is NOT commonly a cause of low engine oil pressure?
• Does the impeller of a diesel engine react to engine heat?
• Which of the following oil filter designs is used in modern diesel engines?
• Which ignition method promotes efficient fuel combustion in a diesel engine?
• What can excessive engine idle time cause?
• Technician A says that cylinder block torque twist can be the result of high cylinder pressures. Technician B says that cylinder block torque twist can be the result of drivetrain forces outside of the engine. Who is correct?
• Who is correct about the cooling of diesel engine exhaust manifolds in highway applications?
• Which technician indicates that the engine oil cooling system needs to be checked after bearing damage?
• What can excessive pressure testing of the cooling system lead to?
• Class C fires involve which type of materials?
• What is a primary consequence of not removing contaminants from air in diesel engines?
• Which technician states that engine oil can warm up faster than engine coolant?
• Which series of engine oils is specifically used in diesel engines?
• Who accurately describes pressurization's role in the coolant system?
• What happens when using incompatible long-life anti-freeze?
• In troubleshooting engine overheating conditions, which technician is correct regarding the radiator shroud?
• When testing for leaks in a cooling system, what is the maximum pressure that should be applied according to Technician A?
• Who is correct about the impact of air contaminants?
• What should be checked first if truck radiator hoses collapse internally as the engine cools?
• Which measuring tool is most accurate for measuring a component thickness of around .0015 inches?
• Who is correct regarding the revolutions of the crankshaft and camshaft in a two-cycle engine?
• Who states that there is no difference between diesel engine oil and spark-ignition engine oil?
• Up to which temperature can an engine with a 10 psi pressure cap prevent cooling system boil over?
• Technician A says to replace all original Grade 5 fasteners with Grade 8 when performing suspension repairs. Technician B says that a Grade 8 rated Huck fastener may be replaced with a Grade 8 nut and bolt. Who is right?
• The water pumps in diesel engines can be driven by which of the following?
• What key factor does Technician B mention about anti-freeze effects?
• Who is correct regarding the use of helical inserts for repairing damaged bolt holes?
• Newer formulations of premium long-life antifreeze using organic acids require what level of nitrite compared to older formulations?
• At what temperature can Diesel Particulate Filters regenerate?
• Who is correct about exhaust ports and passages: Technician A says they are large for free flow, while Technician B claims they are narrow for fast movement of gases?
• Technician A states that diesel exhaust oxidation catalysts function similarly to those used in automobiles. Technician B says that they must store noxious emissions when exhaust temperatures are low. Who is correct?
• In the use of Plastigauge, what does a wider gauge indicate?
• What type of clothing is recommended for safety when working in a shop?
• What occurs as the piston completes its compression stroke, according to Technician A?
• How does compression in a diesel engine affect fuel combustion?
• What does Technician A claim about the distance from the crankshaft to the connecting rod journal?
• What is usually the reason for a "knocking" sound in a diesel engine?
• Who is accurate about the operation of the crankshaft and camshaft in a two-cycle engine?
• What is a primary function of an oil cooler within an engine?
• What can pressure testing a cooling system identify?
• What do some head gaskets incorporate to help contain heat and pressure?
• A plugged or dirty filter can cause what effect in terms of combustion?
• What does the acronym BDC stand for in relation to an engine piston?
• Who is correct regarding the engine oil specifications used in the summer?
• Why might turbochargers be considered less advantageous than superchargers?
• Where does cavitation erosion normally occur on a wet liner?
• How many flats does a hex nut have?
• Which instrument is specifically designed to measure rotational speed?
• What is the purpose of using a thickness gauge and straight edge on a cylinder block?
• What is suggested as a possible cause for a high amount of oil consumption in a diesel engine?
• What is the typical style of most modern crankshaft seals?
• Which technician is correct about appropriate work clothes in a shop environment?
• What is the alternate name for the power stroke in the engine cycle?
• What set of variables is required to measure horsepower?
• What must be maintained to prevent corrosion in a cooling system?
• Which technician claims that diesel engine oil operates at higher temperatures?
• What is the preferred method for removing a tough to remove gasket from an oil pan flange?
• What does the use of SCR deliver?
• What is the primary purpose of adding silicate to anti-freeze?
• Which factor best accounts for a diesel engine's high thermal efficiency?
• Who is correct regarding battery discharge in vehicles?
• What is the optimum pH level for a cooling system?
• What is one cause of oil leaking from exhaust ports according to Technician B?
• Who is right about the compatibility of long-life anti-freeze?
• Each 2 psi of back pressure is estimated to cause a loss of how much engine horsepower?
• When EGR systems are added to diesel engines, what oil properties must change?
• What is a potential issue if the crankshaft or camshaft fails?
• Using an external blower to clean a cylinder of combustion gases is known as what?
• When sealing the oil pan from leaks, what tools should be used?
• Regarding connecting rods, who is correct about the distance from the crankshaft centerline?
• When selecting a hacksaw blade to cut light angle iron, what is the recommended teeth per inch (tpi)?
• What can bubble collapse lead to in a wet liner engine?
• What are modern crankshaft seals designed to prevent?
• Which tool does Technician A say can cut hardened rods?
• What component should be handled with care when rebuilding a diesel engine water pump?
• Is the manometer used for testing the coolant system psi?
• What is a key benefit of using core plugs in engine designs?
• What type of ignition system is used in diesel engines to ignite fuel?
• What is a typical component found in safety signage?
• Who is correct regarding the identification of the upper shell of a main bearing?
• If a single slab cylinder head is used on an in-line 6-cylinder diesel engine, how many engine cylinders will the cylinder head cover?
• Who is correct about the method to measure liner protrusion?
• Crankshaft counterweights are primarily used to minimize engine vibration caused by what?
• Who is correct regarding airflow impacts in the air system: Technician A states that too many bends in the piping can restrict airflow, while Technician B says leaks allow dirt into the engine?
• What is the primary objective of torquing a nut and bolt?
• In terms of efficiency, who is correct about superchargers and turbochargers?
• What is the correct order of the four piston strokes of a four-stroke engine?
• Regarding crankshaft end play, who provides the correct information?
• What should be worn when using cleaning chemicals due to their toxicity?
• Which steps should be checked when installing an intake manifold?
• What is the main role of the crankshaft in an engine cycle?
• What happens to the pistons during the exhaust and compression strokes?
• What type of coolant pump is most commonly used in highway diesel engines?
• What is a likely consequence of a damaged radiator shroud?
• What happens to diesel engine oil compared to spark-ignition engine oil in terms of color change over time?
• In a two-cycle engine, how do the camshaft and crankshaft relate in terms of speed?
• What does the outside micrometer measure?
• When using Plastigauge, what does it mean if the Plastigauge becomes wider?
• What is a primary characteristic of centrifugal coolant pumps in diesel engines?
• What is a list of steps required for consistency in task performance called?
• Who is correct about measuring the bottom of a cylinder?
• What is the result of filter restriction in diesel engine air filters?
• When should engine oil be changed in a diesel engine?
• Which technician is correct about the use of a garter spring in lip-type seals?
• What process supplements air supply to the intake system by increasing pressure?
• What is the primary function of the turbocharger in a diesel engine?
• What is a potential outcome of high cylinder pressures in an engine?
• During engine operation, what condition would typically cause low oil pressure?
• Which is a common cause for high oil consumption in engines?
• What is the function of a fire ring in a head gasket?
• Who is correct regarding safety when guiding a vehicle onto an inspection pit?
• Which of the following statements about slow charging a battery is true?
• What concern does Technician A raise regarding new long-life anti-freeze?
• When is it recommended to drain engine oil for maintenance?
• In a heavy duty diesel engine, which of the following is more likely to be described as tuned?
• What is the likely effect of using a low-grade engine oil in a diesel engine?
• What is a common issue with long-life anti-freeze according to Technician B?
• What effect does tightening the exhaust valve adjustments have?
• What is typically used in conjunction with a castellated nut?