Page 89 - Apprentice Manual_Neat

S4-Q88.) Why should fault indicators never be combined?

a.) For quick isolation of a problem
Yes, individual sensor will aid in determining the problem.
b.) Major problems may be masked by minor faults
Yes, if an indicator continuously is activated by minor faults, it may be ignored during a catastrophic
fault.
c.) Small problems may shut down the entire system
Yes, if the controller shuts down when an indicator is activated and minor faults are tied to major, it
could shut down for something that would otherwise be routine.
d.) *All of the above
Correct. Each of the above answers is valid.

S4-Q89.) The term “overcrank” refers to?

a.) Out of limits on crankshaft bending
Is wrong because crankshaft bending relates to web deflection, not overcranking.
b.) *Engine failure to start
Is correct because the starter keeps turning until the engine starts. It “overcranks” when the
engine does not start.
c.) Starter failure to terminate when engine starts
Is wrong because the overcrank relates to the starter continuing to crank the engine only when the
engine does not start. Failure to terminate relates to the starter itself failing to return to the “non
engaged” position whether the engine starts or not.
d.) Starter failure to disengage
Is wrong because the term for starter disengage is “crank termination” not overcrank.

S4-Q90.) What is the primary purpose of heating the engine coolant before start up?

a.) It heats the fuel for better combustion
Is wrong because engine coolant is not tied in with the fuel tank. Other types of fuel heaters are used.
b.) It keeps the intake air system at a constant temperature.
Is wrong. Even though some intake air in a non running engine is heated, the primary purpose of a
preheater is maintaining increased engine block temperature.
c.) It keeps the thermostat open for quick starting efficiency
Is wrong because preheaters are unrelated to the engine thermostat open or closed. They are made to
circulate through the engine only with their own coolant pump.
d.) *It keeps the engine warmed up for quick starting efficiency
Is correct because a preheater keeps the block temperature increased to allow for more instant
start up on demand and less engine wear as engine RPM increases rapidly upon start up
Increased engine wear and possible failure can occur on an engine that is started in that manor
without being preheated.

S4-Q91.) Why must an engine temperature be controlled?

a.) An engine operates most efficiently at certain temperature ranges.
Is correct-research indicates engine operates efficiently at a range of 170-210 degrees F.
b.) Excessively high temperatures increase engine wear.
Is correct-when an engine operating temperature is excessively high, coolant boils and loses cooling
capacity, oil oxidizes and metal to metal contact occurs.
c.) Excessively low temperatures reduce combustion efficiency
Is correct because fuel does not burn in the combustion cycle efficiently and emissions increase.
d.) *All of the above
Is the most correct because all three previous answers were equally correct.

Page 81 - EGSA Apprentice Certification Program Study Guide