Ase practice test (diesel engine) T2 (Answered)

A diesel engine has excessive oil consumption with no visible oil leaks. Which of these could be the cause? - ANSWER (D) A leaking turbocharger impeller shaft seal Which of these could be the cause of blue smoke from the exhaust on a vehicle that is not equipped with an exhaust aftertreatment system? - ANSWER (C) Worn piston rings During long uphill pulls, a delivery truck equipped with an engine protection system activates a warning light and buzzer, and the engine derates power. Which of these could be the cause? - ANSWER (C) A partially restricted radiator core Which of these could be the cause of a loud ticking noise on a diesel engine? - ANSWER (A) Excessive valve lash Excessive white smoke is observed coming from the exhaust. Which of these could be the cause? - ANSWER (A) A leaking fuel injector cup A diesel engine has excessive vibration. Technician A says that binding variable geometry turbocharger (VGT) vanes could be the cause. Technician B says that a broken flywheel/flexplate could be the cause. - ANSWER (B) B only The measurement in the setup shown indicates that a new valve is too high. Which of these steps will correct the problem? - ANSWER (D) Remove material from the valve seat. Technician A says that debris in the cylinder head bolt holes can affect head bolt clamping force. Technician B says that using over-stretched cylinder head bolts can affect head bolt clamping force. Who is right? - ANSWER (C) Both A and B Cylinder liner protrusion (height) that is too low can be adjusted by: - ANSWER (C) adding cylinder liner shims. A truck engine has excessive crankcase pressure. During disassembly, the technician notices excessive wear on the cylinder walls and upper piston rings. Which of these could be the cause? - ANSWER (B) A missing engine air filter seal While servicing an engine, the technician finds a slight amount of scoring on the engine side of the flywheel. Technician A says that excessive crankshaft endplay could be the cause. Technician B says that missing bell housing locating pins could be the cause. Who is right? - ANSWER (A) A only The oil pressure gauge indicates low engine oil pressure at higher engine rpm only. Which of these could be the cause? - ANSWER (A) A restricted oil pump pickup screen During inspection, the technician observes engine oil in the coolant expansion tank. This could be caused by a leaking: - ANSWER (D) oil cooler heat exchanger. A diesel engine is being diagnosed for overheating. Once the engine reaches operating temperature, coolant leaks out of the overflow. Which of these could be the cause? - ANSWER (B) A leaking cylinder head gasket While performing a stationary regeneration, the technician notices no significant rise in the diesel oxidation catalyst (DOC) temperature. Which of these could be the cause? - ANSWER (C) An exhaust leak in front of the DOC A diesel engine is being diagnosed for coolant consumption. There are no external leaks and the engine oil does not show coolant contamination. Which of these could be the cause? - ANSWER (D) A failed EGR cooler A diesel engine equipped with an exhaust aftertreatment system emits black smoke from the exhaust. Which of these could be the cause? - ANSWER (C) An internally failed diesel particulate filter (DPF) A diesel engine equipped with a high-pressure common rail (HPCR) fuel system cranks normally, but will not start. Which of these could be the cause? - ANSWER (A) An internally leaking fuel pressure limiting valve An electronic diesel engine has low power only while under load. This could be caused by a: - ANSWER (A) restricted intake manifold pressure sensor port. A diesel engine with a hydraulic electronic unit injector (HEUI) fuel system will not start. During diagnosis, there is no injection control pressure (ICP). Which of these could be the cause? - ANSWER (D) A low engine oil level An electronic diesel engine stalls while driving. After stalling, the engine cranks but will not restart. Technician A says that a failed engine position sensor could be the cause. Technician B says that a failed throttle position sensor could be the cause. - ANSWER (A) A only An electronic diesel engine has low power. No diagnostic trouble codes (DTCs) are stored and the check engine light is not illuminated. Which of these could be the cause? - ANSWER (B) A partially restricted fuel filter An electronic unit injector (EUI) is being replaced. Technician A says that the oil may need to be bled from the gallery before removing the injector. Technician B says that injector calibration codes may need to be programmed in the ECM after installing the new injector. Who is right? - ANSWER (B) B only After connecting to the truck with a laptop that has the correct software application, the technician observes a failure to communicate message. The truck runs normally and no warning lights are displayed on the dash. Which of these could be the cause? - ANSWER (D) A poor connection at the 9-pin diagnostic connector A truck has an "Engine Coolant Temperature (ECT) Sensor Signal Circuit High" DTC. During diagnosis with the key ON/engine OFF, the technician observes the digital multimeter (DMM) measurement shown. Which of these could be the cause? - ANSWER (B) An open circuit at X A truck has an overcharging condition. Technician A says that high resistance in the alternator case ground could be the cause. Technician B says that high resistance in the alternator remote sensing circuit could be the cause. Who is right? - ANSWER (B) B only A truck has a no-crank condition. With the ignition switch in the START position, the technician observes the digital multimeter (DMM) measurement shown. The cause could be an open circuit at: - ANSWER (C) Y. The compression brake functions but performance is weak on a truck equipped with an electronic diesel engine. Which of these could be the cause? - ANSWER (D) Misadjusted slave pistons