Mariner Mercury 105/140 JET, Руководство по обслуживанию

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90-824052R3 JUNE 2002 POWERHEAD - 4A-31
4. Water Marks: When bearing surfaces are sub-
jected to water contamination, a bearing surface
“etching” occurs. This etching resembles the size
of the bearing.
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5. Spalling: Spalling is the loss of bearing surface,
and it resembles flaking or chipping. Spalling will
be most evident on the thrust portion of the
connecting rod in line with the “I” beam. General
bearing surface deterioration could be caused by
or accelerated by improper lubrication.
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a
a - Spalling
6. Chatter Marks: Chatter marks are the result of a
combination of low speed - low load - cold water
temperature operation, aggravated by
inadequate lubrication and/or improper fuel.
Under these conditions, the crankshaft journal is
hammered by the connecting rod. As ignition
occurs in the cylinder, the piston pushes the
connecting rod with tremendous force, and this
force is transferred to the connecting rod journal.
Since there is little or no load on the crankshaft,
it bounces away from the connecting rod. The
crankshaft then remains immobile for a split
second until the piston travel causes the
connecting rod to catch up to the waiting
crankshaft journal, then hammers it. The
repetition of this action causes a rough bearing
surface(s) which resembles a tiny washboard. In
some instances, the connecting rod crank pin
bore becomes highly polished. During operation,
the engine will emit a “whirr” and/or “chirp” sound
when it is accelerated rapidly from idle speed to
approximately 1500 RPM, then quickly returned
to idle. If the preceding conditions are found,
replace both the crankshaft and connecting
rod(s).
a
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a - Chatter Marks Between Arrows
7. Uneven Wear: Uneven wear could be caused by
a bent connecting rod.
a
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a - Uneven Wear Between Arrows
8. If necessary, clean connecting rod bearing
surfaces, as follows:
a. Be sure that “etched” marks on connecting
rod (crankshaft end) are perfectly aligned
with “etched” marks on connecting rod cap.
Tighten connecting rod cap attaching bolts
securely.
CAUTION
Crocus cloth MUST BE USED to clean bearing
surface at crankshaft end of connecting rod. DO
NOT use any other type of abrasive cloth.
b. Clean CRANKSHAFT END of connecting
rod by using CROCUS CLOTH placed in a
slotted 3/8 in. (9.5mm) diameter shaft, as
shown. Chuck shaft in a drill press and
operation press at high speed while keeping
connecting rod at a 90
°
angle to slotted shaft.