Remove Cylinder Heads And Hydraulic Lifters; Disassemble Cylinder Heads; Bleeding Lifters; Valve Guides - Kohler CH940-CH1000 Service Manual

Disassembly

Remove Cylinder Heads and Hydraulic Lifters

NOTE: Exhaust lifters are located on output shaft side
of engine while intake lifters are located on fan
side of engine. Cylinder head number is
embossed on outside of each cylinder head.
1. Remove pipe plug from cylinder head to access
screw in upper center location.
2. Remove fi ve hex fl ange screws securing each
cylinder head. Note locations of washers and spacer.
3. Mark position of push rods as either intake or
exhaust and cylinder 1 or 2. Push rods should
always be reinstalled in same positions.
4. Carefully remove push rods, cylinder head and head
gasket.
5. Repeat procedure for or cylinder head.
6. Remove lifters from lifter bores. Use a Hydraulic
Lifter Tool. Do not use a magnet to remove lifters.
Mark lifters by location, as either intake or exhaust
and cylinder 1 or 2. Hydraulic lifters should always
be reinstalled in same position.
Inspection
Check base surface of hydraulic lifters for wear or
damage. If lifters need to be replaced, apply a liberal
coating of Kohler lubricant to base of each new lifter
before it is installed.

Bleeding Lifters

To prevent a possible bent push rod or broken rocker
arm, it is important to bleed any excess oil out of lifters
before they are installed.
1. Cut a 50-75 mm (2-3 in.) piece from end of an old
push rod and chuck it in a drill press.
2. Lay a rag or shop towel on table of drill press and
place lifter, open end up, on towel.
3. Lower chucked push rod until it contacts plunger in
lifter. Slowly pump plunger two or three times to
force oil out of feed hole in side of lifter.

Disassemble Cylinder Heads

NOTE: These engines use valve stem seals on intake
and exhaust valves. Use a new seal whenever
valves are removed, or if seal is deteriorated in
any way. Never reuse an old seal.
1. Remove two hex fl ange screws, rocker arm pivots,
and rocker arms from cylinder head.
2. Compress valve springs using a valve spring
compressor.
3. Once valve spring is compressed, remove following
items:
● Valve spring keepers
● Valve spring retainers
● Valve springs
● Valve spring caps
● Intake and exhaust valves (mark position)
● Valve stem seals
4. Repeat above procedure for or cylinder head. Do not
interchange parts from one cylinder head to or.
50
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 0.076 mm (0.003 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 a
warped head, excessive corrosion, or a 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, determine
whether valve stem or guide is responsible for excessive
clearance.
Maximum (I.D.) wear on intake valve guide is 7.135 mm
(0.2809 in.) while 7.159 mm (0.2819 in.) is maximum
allowed on exhaust guide. Guides are not removable but
can be reamed 0.25 mm (0.010 in.) oversize. Valves with
0.25 mm oversize stems must then be used.
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. Final cut
should be made with an 89° cutter as specifi ed for
valve seat angle. Cutting proper 45° valve face angle
as specifi ed, and proper valve seat angle (44.5°, half of
full 89° angle), will achieve desired 0.5° (1.0° full cut)
interference angle where maximum pressure occurs on
outside diameters of valve face and seat.
KohlerEngines.com 62 690 01 Rev. C