A+ SCORE ASSURED (100% VERIFIED)
"with the engine idling, a vacuum gauge connected to the intake manifold fluctuates (from
15 to 20). These fluctuations may be caused by
late ignition timing,
intake manifold vacuum leaks,
a restricted exhaust system,
sticky valve stems and guides, - CORRECT ANSWER sticky valve stems and guides
-late ignition timing would result in a low, steady reading
-intake manifold leaks would cause a very low, steady reading
-a restricted exhaust system would cause vacuum to slowly decrease after the engine was
accelerated and held steady"
"oil is leaking from the crankshaft rear main bearing seal on an engine. Tech A says the oil
seal could be faulty. Tech B says the PCV system may not be functioning.
A,
B,
A & B,
Neither, - CORRECT ANSWER A&B"
"A high-pitched squealing noise is heard during hard acceleration. This may be the cause of:
intake manifold leak,
the choke stuck closed
fuel system leak
small leak in exhaust manifold - CORRECT ANSWER small leak in exhaust manifold
-intake manifold leak causes a high-pitched whistle at idle and low speeds
-carb choke stuck closed will not cause a high-pitched whistle
-fuel system leak normally would not cause a noise"
"a heavy thumping noise occurs with the engine idling, but the oil pressure is normal. this
may be caused by:
worn pistons and cylinders,
loose flywheel bolts,
worm main bearings,
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, loose camshaft bearings, - CORRECT ANSWER loose flywheel bolts
-worn pistons and cylinders would cause a thumping noise during acceleration
-worn main bearings cause a thump when the engine is started
-loose camshaft bearings would cause a growling noise at all times"
"after a vehicle is parked overnight and then started in the morning, the engine has a lifter
noise that disappears after running for a short time. this may be caused by:
low oil pressure,
low oil level,
worn lifter bottom,
excessive lifter leak-down, - CORRECT ANSWER excessive lifter leak-down
low oil pressure would result in a continuous noise
low oil level would result in a continuous noise
worn lifter bottom would result in a continuous noise"
"when using a compression tester, the readings on the cylinders are all even, but lower
than spec. this could indicate:
blown head gasket,
carbon buildup,
cracked head,
worn rings and cylinders, - CORRECT ANSWER worn rings and cylinders
-a low reading on two adjacent cylinders may indicate a blown head gasket
-carbon buildup would cause a high reading
-a low reading on two adjacent cylinders may indicate a cracked head"
"a cylinder balance test is being performed on an engine to determine which cylinder is
causing a miss.
Tech A says that when the faulty cylinder is disabled, engine rpm will drop more than for
the other cylinders.
Tech B says disabling the faulty cylinder will cause the engine to stall
A,
B,
Both,
Neither, - CORRECT ANSWER Neither
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, the faulty cylinder will not cause the engine to stall, neither will it cause the engine to drop
in RPM since it is faulty."
"an engine is idling at 750 rpm. the pointer on the vacuum gauge is floating between 11 and
16 in Hg. The most likely cause is
retarded timing,
advanced timing,
stuch EGR valve,
too lean idle mixture, - CORRECT ANSWER too lean idle mixture
all others would not result in gauge fluctuation"
"the first step a Tech should take for diagnosis is:
think of possible causes of the problem,
question the customer,
road test the vehicle,
listen to the customer, - CORRECT ANSWER listen to the customer"
"if the starter motor does not crank the engine, the first diagnostic step a tech should take
is:
disable the ignition system
remove the spark plugs
rotate the engine by hand
watch for oil or coolant flow from spark plug holes - CORRECT ANSWER disable the
ignition system
-ignition first, rotate (if possible), then remove spark plugs to rotate and check for coolant
or oil"
"Tech A says blue-gray smoke coming from the exhaust may be caused by stuck piston
rings.
Tech B says this could be caused by a plugged oil drain passage in the cylinder head...
A
B
Both
Neither - CORRECT ANSWER Both
2
, Both stuck piston rings and a plugged oil drain passage may allow oil to enter the cylinder
and emit a blue/gray smoke when burned in the chamber"
"a tech has added fluorescent dye to an engine crankcase in order to locate an oil leak. The
dye will glow when it is exposed to:
a fluorescent light
an ultraviolet light
a strobe light
an infrared light - CORRECT ANSWER An ultraviolet light
-All others won't cause the dye to glow"
"measurement B in the figure is more than specified.
Tech A says this problem may bottom the lifter plunger.
Tech B says a shim should be installed under the valve spring.
A
B
Both
Neither - CORRECT ANSWER B only
Measure the installed valve spring height from the lower edge of the top retainer to the
spring seat.
Tech A is wrong. Excessive installed valve spring height will not cause the lifter plunger to
bottom. Excessive installed valve spring height reduces valve spring tension, which may
result in valve float and cylinder misfiring at higher speeds.
Tech B is correct because is the measurement is excessive, install shims between the
bottom of the valve spring and the top of the spring seat surface on the cylinder head."
"Tech A says worn valve lock grooves may cause the valve locks to fly out of place with the
engine running, resulting in severe engine damage.
Tech B says worn valve lock grooves may cause a clicking noise with the engine idling
A
B
Both
Neither - CORRECT ANSWER A
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