Kohler Command PRO CH260 [72/100] Disassembly inspection and service
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Kohler Command PRO CH260 [72/100] Disassembly inspection and service

Kohler Command PRO CH440 [72/100] Disassembly inspection and service
72
Disassembly/Inspection and Service
KohlerEngines.com 17 690 01 Rev. J
Remove Valve Cover/Breather, Rocker Arms, Push
Rods, and Cylinder Head Assembly
NOTE: Mark location of push rods and any other part
removed being reused.
1. Remove screw and washer and remove valve cover
and gasket from engine. Breather assembly is inside
valve cover.
2. Loosen and remove rocker arm lock and adjuster
nuts. Remove rocker arms and push rods.
3. Remove spark plug.
4. Remove screws securing cylinder head.
5. Remove cylinder head, dowel pins, and cylinder
head gasket.
Breather System
Breather system is designed to control amount of oil
in head area and still maintain necessary vacuum in
crankcase.
When pistons move downward, crankcase gases are
pushed past reed through mesh fi lter into intake system.
Upward travel of pistons closes reed and creates a
low vacuum in lower crankcase. Any oil separated out
through fi lter drains back into crankcase.
Remove Valves
NOTE: Mark locations of any part removed being
reused.
1. Supporting head of valve from below, depress valve
keeper and valve spring until keeper can be
released from valve stem. Remove valve spring and
valve from head. Repeat this procedure for
remaining valve.
2. Remove and replace valve stem seals whenever
cylinder head is serviced or disassembled.
Inspection and Service
After cleaning, check fl atness of cylinder head and
corresponding top surface of crankcase, using a surface
plate or piece of glass and feeler gauge. Maximum
allowable out of fl atness is 0.1 mm (0.0039 in.).
Carefully inspect valve mechanism parts. Inspect valve
springs and related hardware for excessive wear or
distortion. Check valves and valve seat area or inserts
for evidence of deep pitting, cracks, or distortion. Check
clearance of valve stems in guides.
Hard starting, or loss of power accompanied by high
fuel consumption may be symptoms of faulty valves.
Although these symptoms could also be attributed to
worn rings, remove and check valves fi rst. After removal,
clean valve heads, faces, and stems with a power wire
brush.
Then, carefully inspect each valve for defects such as
warped head, excessive corrosion, or worn stem end.
Replace valves found to be in bad condition.
Valve Guides
If a valve guide is worn beyond specifi cations, it will not
guide valve in a straight line. This may result in burnt
valve faces or seats, loss of compression, and excessive
oil consumption.
To check valve guide-to-valve stem clearance,
thoroughly clean valve guide and, using a split-ball
gauge, measure inside diameter of guide. Then, using
an outside micrometer, measure diameter of valve stem
at several points on stem where it moves in valve guide.
Use largest stem diameter to calculate clearance by
subtracting stem diameter from guide diameter. If intake
or exhaust clearance exceeds specifi cations in Valve
Specifi cation table, determine whether valve stem or
guide is responsible for excessive clearance.
If guides are within limits but valve stems are worn
beyond limits, install new valves.
Valve Seat Inserts
Hardened steel alloy intake and exhaust valve seat
inserts are press-fi tted into cylinder head. Inserts are
not replaceable but can be reconditioned if not too badly
pitted or distorted. If cracked or badly warped, cylinder
head should be replaced.
Recondition valve seat inserts following instructions
provided with valve seat cutter being used. Cutting
proper valve face angle, as specifi ed in Valve
Specifi cation table and proper valve seat angle (89.5°-
90°) will achieve desired 0° (1° full cut) interference
angle where maximum pressure occurs on outside
diameters of valve face and seat.
Lapping Valves
Reground or new valves must be lapped in, to provide
proper fi t. Use a hand valve grinder with suction cup
for fi nal lapping. Lightly coat valve face with fi ne grade
of grinding compound, then rotate valve on seat with
grinder. Continue grinding until smooth surface is
obtained on seat and on valve face. Thoroughly clean
cylinder head in soap and hot water to remove all traces
of grinding compound. After drying cylinder head, apply
a light coating of SAE 10 oil to prevent rusting.
Valve Stem Seals
These engines use valve stem seals on intake and
exhaust valves.
Always use new seals when valves are removed
from cylinder head. Seals should also be replaced if
deteriorated or damaged in any way. Never reuse old
seals.

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