Deck 52: Troubleshooting and Diagnostics

Question 1

If an engine is leaking coolant into its cylinders, which of the following would most likely result?

A) black smoke emission
B) green smoke emission
C) red smoke emission
D) white smoke emission

Answer 1

white smoke emission

Question 2

Blue smoke emission from a truck diesel engine is usually caused by:

A) an oil leak
B) semi-combusted oil in the exhaust gas
C) over-fueling
D) air starvation

Answer 2

semi-combusted oil in the exhaust gas

Question 3

If an engine is tested and found to be emitting high NOx, what color would the exhaust gas emission be?

A) blue
B) white
C) black
D) clear

Answer 3

clear

Question 4

A diesel engine is emitting black smoke, especially under load. Which of the following should be performed first?

A) check inlet restriction on fuel suction side
B) check air filter inlet restriction
C) check for high exhaust back pressure
D) perform an engine overhead adjustment

Question 5

How should a cylinder misfire be checked out on an electronically-controlled fueled diesel engine?

A) sequentially short out each injector by cracking each high pressure pipe
B) remove the exhaust manifold and check for smoke
C) mechanically hold the EUI rocker in its down position
D) use an EST to perform an electronic cylinder cutout test

Question 6

What color smoke is associated with diesel engine start-up in extreme cold weather conditions?

A) gray
B) black
C) blue
D) white

Question 7

When troubleshooting the cause of low oil pressure readings on a dash gauge, which of the following should be done first?

A) rebuild the oil pump
B) replace the piston oil control rings
C) check with a master gauge
D) reset the pressure relief valve

Question 8

What is the most likely result of a diesel engine with too much oil in the sump?

A) blue smoke emission
B) aerated engine oil
C) engine runaway
D) hard cranking

Question 9

Which of the following instruments is designed for testing the exhaust gas temperature in a diesel engine?

A) digital multimeter (DMM)
B) scan tool
C) pyrometer
D) thermistor

Question 10

If the aneroid device on a hydromechanical diesel engine has been tampered with, which of the following is more likely?

A) increase in black smoke emission
B) increase in white smoke emission
C) reduction in engine power
D) increased engine power

Question 11

Which of the following can restrict a secondary fuel filter sufficiently to shut down diesel engine?

A) diesel fuel conditioner
B) Water
C) alcohol
D) kerosene

Question 12

Which of the following is the more likely cause of an engine hunting condition?

A) unbalanced fuel delivery by injectors
B) damaged aneroid device
C) low CN value of fuel
D) plugged air filter

Question 13

Which of the following can cause abnormally high DPF intake temperatures?

A) restricted boost air heat exchanger
B) high air filter inlet restriction
C) high altitude operation
D) any of the above

Question 14

What is a common cause of injector scuffing?

A) use of 1D diesel fuel
B) adding methyl hydrate to fuel tank
C) prolonged periods of high engine loading
D) running at excessive road speeds

Question 15

Which of the following conditions could result in high engine exhaust temperature?

A) Advanced injection timing
B) Leak in the air intake circuit
C) Restricted air intake system
D) All of the above

Question 16

All of the following can cause a low oil pressure condition EXCEPT:

A) fuel in lube
B) excessive main bearing clearance
C) oil pump relief valve stuck closed
D) excessive rocker shaft bushing clearance

Question 17

Which of the following could result in abnormally high manifold boost on an engine with a VGT turbocharger?

A) sticking VGT vane ring
B) retarded injection timing
C) plugged charge air cooler
D) restricted DPF

Question 18

When inspecting a cracked DPF core, there is evidence of scorched fuel in the substrate. What should be done after replacing the DPF?

A) send a fuel sample off for testing
B) change the fuel filters
C) replace all the injectors
D) perform a cylinder balance test

Question 19

A diesel engine produces a vibration complaint. Which of the following would be the more likely cause?

A) oil level in pan at low mark on dipstick
B) dent in the viscous vibration damper
C) broken cylinder head bolt
D) advanced injection timing

Question 20

Technician A says that a low oil pressure reading can be caused by insufficient oil in the crankcase. Technician B says that a low oil pressure reading can be caused by excessive oil in the crankcase. Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 21

You are checking a boosted diesel air intake system for inlet restriction using a negative pressure gauge. Which of the following would be the typical maximum acceptable spec reading on the gauge?

A) 10 inches Hg restriction
B) 25 inches Hg restriction
C) 10 inches H₂O restriction
D) 25 inches H₂O restriction

Question 22

When troubleshooting an electronic problem on a current diesel engine, which of the following should be the most reliable source of OEM information?

A) CD-ROM
B) DSM
C) DVD-ROM
D) SIS

Question 23

Which of the following conditions would be the more likely source of a coolant in oil condition?

A) Prolonged high load operation
B) Prolonged low load operation
C) Failure of coolant filter pad lock-off ball
D) Leaking fuel injector cup seal

Question 24

Technician A says that when EGR flow rates are high, the result may be excessively high exhaust temperatures. Technician B says that any time exhaust temperatures are excessively high, the cause must relate the breathing circuit downstream from the engine cylinder. Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 25

What does HD-OBD specifically mandate?

A) Enabling J1939 bus access
B) Enabling bus access to emissions-related fault repairs
C) Improving diesel engine fuel economy
D) All of the above

Question 26

Technician A says that an engine malfunction on a Mack electronic engine manufactured between 2002 and 2010 can have up to 10 possible causes. Technician B says that an electronic engine malfunction on a post-2010 Mack engine can have up to 25 possible causes. Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 27

Technician A says that frequent DPF regeneration cycles can be an indication of a serious internal engine problem. Technician B says in the event of a DPF malfunction, a DTC will be logged before any damage can occur to the DPF. Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 28

What is the function of the OEM district service manager (DSM) in the repair cycle??

A) ?Denial of all warranty claims
B) ?Manage day to day troubleshooting
C) ?Train dealership techs
D) ?Advise dealer techs on advanced level troubleshooting