Service and Repairs

76
Disassembly/Inspection and Service
KohlerEngines.com 17 690 01 Rev. L
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.
NOTE: CH245/CH255 valve cover is sealed to cylinder
head using RTV silicone sealant. When
removing valve cover, use care not to damage
sealing surfaces of cover and cylinder head. To
break RTV seal, hold a block of wood against 1
fl at face of valve cover. Strike wood fi rmly with a
mallet. If seal doesn't break loose after 1 or 2
attempts, repeat procedure on other side.
1. CH245/CH255: Remove screws and remove valve
cover from engine. Breather assembly is inside valve
cover. Using a brass wire brush and gasket remover
or similar solvent, clean old RTV from surface of
cylinder head and valve cover.
CH260-CH440: Remove screw and washer, then
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 (note location for
reassembly), 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 precision straight edge and feeler gauge.
Maximum allowable out of fl atness is:
0.1 mm (0.0039 in.) for CH245, CH255, CH395, CH440.
0.08 mm (0.003 in.) for CH260, CH270.
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.