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55
Disassembly/Inspection and Service
17 690 01 Rev. F
KohlerEngines.com
Dimension B
B
Cam Lobe Specifi cations
Engine
Model
Valve
Dimension B
Service Limit
CH260,
CH270
INTAKE
21.8 mm
(0.858 in.)
21.5 mm
(0.848 in.)
EXHAUST
21.8 mm
(0.858 in.)
21.5 mm
(0.848 in.)
CH395
INTAKE
25.94 mm
(1.021 in.)
25.68 mm
(1.011 in.)
EXHAUST
25.94 mm
(1.021 in.)
25.68 mm
(1.011 in.)
CH440
INTAKE
25.94 mm
(1.021 in.)
25.68 mm
(1.011 in.)
EXHAUST
25.94 mm
(1.021 in.)
25.68 mm
(1.011 in.)
Dimension C
C
Camshaft Journal Specifi cations
Engine Model
Dimension
Limit
CH260, CH270
13.975 mm
(0.5500 in.)
13.900 mm
(0.5470 in.)
CH395, CH440
15.975 mm
(0.6289 in.)
15.900 mm
(0.6260 in.)
Inspect gear teeth of camshaft. If teeth are badly
worn, chipped, or some are missing, replacement of
camshaft will be necessary. If unusual wear or damage
is evident on either lobe or mating tappet, camshaft and
both tappets must be replaced. Check condition and
operation of ACR mechanism.
Measure cam lobe pro
fi
le, A and B, using an outside
micrometer and compare with speci
fi
cations listed.
Measure the camshaft journals, C, which
fi
t in the ball
bearings, for wear using a micrometer. Compare with
speci
fi
cations listed.
Remove Piston, Connecting Rod and Crankshaft
NOTE: If a carbon ridge is present at top of cylinder
bore, use a ridge reamer to remove it before
attempting to remove piston.
1. Remove screws securing end cap to connecting rod.
Remove end cap. Carefully guiding connecting rod,
slide piston and connecting rod from cylinder bore.
2. Remove crankshaft from crankcase.
Connecting Rods Inspection and Service
Check bearing area (big end) for excessive wear, score
marks, running and side clearances (see Speci
fi
cations
and Tolerances). Replace rod and cap if scored or
excessively worn.
Service replacement connecting rods are available
in STD size and 0.25 mm (0.010 in.) undersize. 0.25
mm (0.010 in.) undersized rods have an identi
fi
cation
marking on lower end of rod shank. Always refer
to appropriate parts information to ensure correct
replacements are used.
Piston and Rings Inspection
Scuf
fi
ng and scoring of pistons and cylinder walls occurs
when internal engine temperatures approach welding
point of piston. Temperatures high enough to do this are
created by friction, which is usually attributed to improper
lubrication and/or overheating of engine.
Normally, very little wear takes place in piston boss-
piston pin area. If original piston and connecting rod can
be reused after new rings are installed, original pin can
also be reused but new piston pin retainers are required.
Piston pin is included as part of piston assembly – if pin
boss in piston or pin are worn or damaged, a new piston
assembly is required.
Ring failure is usually indicated by excessive oil
consumption and blue exhaust smoke. When rings fail,
oil is allowed to enter combustion chamber where it is
burned along with fuel. High oil consumption can also
occur when piston ring end gap is incorrect because
ring cannot properly conform to cylinder wall under this
condition. Oil control is also lost when ring gaps are not
staggered during installation.
When cylinder temperatures get too high, lacquer and
varnish collect on pistons causing rings to stick, which
results in rapid wear. A worn ring usually takes on a
shiny or bright appearance.
Scratches on rings and pistons are caused by abrasive
material such as carbon, dirt, or pieces of hard metal.
Detonation damage occurs when a portion of fuel charge
ignites spontaneously from heat and pressure shortly
after ignition. This creates 2
fl
ame fronts, which meet
and explode to create extreme hammering pressures on
a speci
fi
c area of piston. Detonation generally occurs
from using low octane fuels.
Preignition, or ignition of fuel charge before timed spark
can cause damage similar to detonation. Preignition
damage is often more severe than detonation damage.
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