Week #2 Batteries and Starter Circuits

Question 1

Which of the following engine conditions would be the likely cause of a tensile failure of a connecting rod?

a. Prolonged lug down
b. Prolonged engine idling
c. Engine overspeed
d. High cylinder pressures

Answer 1

Engine overspeed

Question 2

Which of the following is a disadvantage of an articulating piston assembly when compared to an aluminum alloy trunk piston?

a. Piston slap control
b. Highest possible location of an upper ring groove
c. Service life
d. Increased tensile loading on the connecting rods

Answer 2

Increased tensile loading on the connecting rods

Question 3

Where would a Ni-Resist insert be located?

Answer 3

Upper ring belt, aluminum trunk position

Question 4

Under which of the following conditions would a piston ring seal more effectively?

a. High cylinder pressures
b. Low cylinder pressures
c. High engine temperatures
d. Low engine temperatures

Answer 4

High cylinder pressures

Question 5

A crankshaft has a fracture failure that appears to have initiated at a throw journal oil hole. Which of the following would be the most likely cause?

a. A failed vibration damper
b. A spun rod bearing
c. A broken main cap
d. Excessive cylinder pressure

Answer 5

A failed vibration damper

Question 6

Which of the following journal surface hardening methods would provide the highest machinability margin?

a. Induction hardening
b. Flame hardening
c. Nitriding
d. Shot peening

Answer 6

Induction hardening

Question 7

Rod and main journal bearing clearances are properly measured with what?

Answer 7

Plastigage

Question 8

What type of piston is favored by diesel engine OEMs in post-2007 products?

Answer 8

Forged steel trunk

Question 9

When observing a disassembled engine, the outer crown edges of all six pistons show signs of melting and erosion. This could be cause by what?

a. Fuel with high sulfur content
b. Advanced timing
c. retarded timing
d. a dribbling injector

Answer 9

Advanced timing

Question 10

Which of the following types of pistons use brushingless pin bosses?

a. Aluminum alloy
b. Crosshead
c. Monotherm
d. Ferrotherm

Answer 10

Monotherm

Question 11

What would be the consequence of a misdirected piston oil cooling jet?

a. Overheated engine lube
b. Fuel in the lube
c. Low oil pressure
d. Torched piston

Answer 11

Torched piston

Question 12

Technician A states that keystone rings are most common in current diesel engines. Technician B states that keystone connecting rods have a wedge-shaped big end. Who is correct?
a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B

Answer 12

Technician A only

Question 13

What should be used to install piston rings onto a piston?

Answer 13

A ring expander

Question 14

Which of the following operating modes would be more likely to result in a compressional failure of a connecting rod?

a. Prolonged low idle running
b. Prolonged high idle running
c. Hydraulic lock caused by head gasket failure
d. Overspeeding engine

Answer 14

Hydraulic lock caused by head gasket failure

Question 15

Which of the following would be the more likely outcome of running an engine with a failed vibration damper?

a. Crankshaft failure
b. Camshaft failure
c. Increased fuel consumption
d. Increased cylinder blowby

Answer 15

Crankshaft failure

Question 16

Into what area of a Mexican hat combustion chamber are the injected droplets of fuel directed?

Answer 16

Crater

Question 17

The upper face of a piston assembly is called what?

Answer 17

Crown

Question 18

Technician A states that a cam ground piston is circular when cold and expands to an elliptical shape at operating temperature. Technician B states that the reason the cam ground piston is elliptical when cold is to accommodate the thermal expansion of the greater mass of material at the piston boss as it is raised to operating temperature. Who is correct?
a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B

Answer 18

Technician B only

Question 19

The piston crown design most commonly used by OEMs in today’s highway diesel engines is the:

a. Barrel face
b. Mexican hat
c. Mann type
d. Dished

Answer 19

Mexican hat

Question 20

What term is used to describe the cylinder volume between the piston upper compression ring and its leading edge?

Answer 20

Headland volume

Question 21

Which of the following is true of a CFA piston?

a. The ring belt operates at higher temperatures
b. It is used only on articulating pistons
c. It is type of Ni-Resist insert
d. The ring belt reinforcement insert extends up into the leading edge of the piston

Answer 21

The ring belt reinforcement insert extends up into the leading edge of the piston

Question 22

When crankshaft thrust surfaces are reground, which of the following would be true?

a. The thrust washers must be shimmed.
b. The thrust washers must be machined to smaller dimension
c. Undersize thrust bearings are required
d. Oversize thrust bearings are required

Answer 22

Oversize thrust bearings are required

Question 23

Technician A states that main bearing shells are usually interchangeable and may be installed in either the upper or lower position. Technician B states that the main bearing shell with an oil hole must always be installed in the main bearing cap. Who is correct?
a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B

Answer 23

Neither A nor B

Question 24

Excessive clearance at the crankshaft main bearings could result in which of the following conditions?

a. High oil pressure
b. Low oil pressure
c. Aerated oil
d. Fluctuating oil pressures

Answer 24

Low oil pressure

Question 25

Technician A states that the type of vibration damper most commonly used on truck diesel engines is the viscous type. Technician B states that the inertia ring drive medium on a viscous-type vibration damper is a rubber compound. Who is correct?
a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B

Answer 25

Technician A only