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When cleaning a cylinder block for final assembly, which of the following should be used?
A. Carburetor cleaner
B. Kerosene or cutting lubricant
C. Hot, Soapy water and a bristle brush
D. Petroleum solvent The correct answer is C. Cylinder walls are best cleaned with hot water
and a stiff bristle brush. Solvents drive grit deeper into the pores of the cast iron cylinder wall.
Technician A says that a cylinder should be bored to within 0.001-in. (0.025mm) of final size.
Technician B says that a plateau finish on the cylinder bore will help seat the piston rings. Who
is right?
A. Technician A only
B. Technician B only
C. Both A and B
D. Neither A or B The correct answer is B. When a cylinder is bored, 0.0025-0.003-in. (0.064-
0.076mm) cylinder wall material is left for finish honing to final size. This is necessary to
completely remove the rough finish left by the boring tool. Following normal honing some
manufacturers recommend a plateau finish in the bore. Plateau honing levels off the peaks left
in the bore surface from honing. As a final polishing step it forms flat plateau areas between the
grooves or valleys of the crosshatch. A plateau surface retains oil and allows faster ring seating,
while reducing ring and cylinder wear.
Technician A says the retainer clips on pistons with floating pins should be reused if they are
not damaged. Technician B says that after a full floating pin bushing is pressed into the rod, the
piston and rod is then reassembled. Who is right?
A. Technician A only
B. Technician B only
,C. Both A and B
D. Neither A or B The correct answer is D, neither technician is right. On engines with a full-
floating wrist pins, the retainer clips at the ends of the pin should always be replaced with new
ones. Full floating pin bushings that are worn are replaced by pressing them in. Then they are
finished honed to provide the correct clearance.
All of the following statements about piston rings are true EXCEPT:
A. Ring end gap must be measured prior to installation.
B. Rings must be installed facing the correct vertical direction.
C. Rings are installed on the piston using a ring compressor.
D. Ring end gaps must be staggered around the piston. The correct answer is C. Rings are
installed on the piston using a ring expander; they are installed in the cylinder with the piston
using a ring compressor.
A manifold vacuum test is performed on an engine in a shop that is located approximately 4000
ft. (1.2km) above sea level. With the engine at normal operating temperature, the gauge reads
a steady 15 in. Hg at idle. Which of the following is indicated by this vacuum reading?
A. Late ignition timing.
B. Low compression.
C. Vacuum leak.
D. Normal operation. The correct answer is D. If the shop was located at seal level, any of
the other answers might be indicated by this vacuum reading. But remember, atmospheric
pressure changes with elevation and vacuum readings must be adjusted accordingly. As an
approximation for ever 1000 ft. above sea level, remove one inch of vacuum. If we correct for
elevation, we can see that this engine would produce 19 in. Hg vacuum at idle at sea level,
which is within the parameters for normal engine operation.
An engine has a light metallic knocking noise during light engine loads, however, when the
cylinder
, with the noise is disabled during a cylinder balance test, the sound diminishes. Technician A
says that the noise is caused by excessive connecting rod bearing clearance. Technician B says
that the noise is caused by excessive piston-to-wall clearance. Who is right?
A. Technician A only
B. Technician B only
C. Both A and B
D. Neither A or B The correct answer is A. When you eliminate the ignition or injection to a
cylinder with a rod knock, the sound diminishes. Unlike a connecting rod bearing noise, piston
slap does not quiet down and may in fact grow louder when you eliminate ignition or fuel
injection to that cylinder.
All of the following are statements describing normal mechanical fan clutch operation EXCEPT:
A. A fan clutch has viscous drag regardless of temperature.
B. A fan clutch varies fan speed according to engine temperature.
C. A fan clutch stops the fan from spinning within two seconds after turning off a hot engine.
D. A fan clutch varies fan speed according to engine speed. The correct answer is D. A
properply operating fan clutch will change the speed of the fan according to engine
temperature. When the engine is cold, the fan clutch does not turn the fan very fast, even
when engine speed is increased. As the engine warms up, the fan clutch increases the speed of
the fan. If the fan speed varies only according to engine speed, regardless of temperature, then
the fan clutch is probably seized and should be replaced.
Which of the following methods can be used to find a cylinder with an internal coolant leak?
A. Draw vapors from the radiator into a vial containing a special chemical and look for the color
change.
B. Hold an exhaust analyzer probe over the radiator neck and check for the presence of exhaust
gases.
C. Perform a leakdown test and look for the presence of bubbles in the radiator coolant.
D. All of the above. The correct answer is C. When performing a leakdown test, if pumping
air into a particular cylinder produces bubbles in the radiator coolant, you know that the leak is