Kohler Command CH20 Service Manual page 79

Assemble Cylinder Heads
Prior to installation, lubricate all components with engine
oil, paying particular attention to lip of valve stem seal,
valve stems and valve guides. Install in order listed
below using a valve spring compressor.
● Intake and exhaust valves.
● Valve spring caps.
● Valve springs.
● Valve spring retainers.
● Valve spring keepers.
Install Cylinder Heads
Cylinder Head Torque Sequence
1
3
2
4
1
NOTE: Cylinder heads must be attached with original
type of mounting hardware, using either screws,
or mounting studs with nuts and washers. Heads
are machined diff erently for studs than for
screws, so fastening method cannot be altered
unless heads are being replaced. Do not
intermix components.
Heads secured with screws:
NOTE: Match numbers embossed on cylinder heads
and crankcase.
1. Check to make sure there are no nicks or burrs on
sealing surfaces of cylinder head or crankcase.
2. Install a new cylinder head gasket, (with printing up).
3. Install cylinder head and lightly lubricate threads of
bolts with engine oil, but be careful not to get any oil
on gasket sealing surfaces. Thread bolts in until
fi nger tight.
4. Torque screws in two stages; fi rst to 22.6 N·m
(200 in. lb.), fi nally to 41.8 N·m (370 in. lb.), following
sequence shown.
Heads secured with mounting studs, nuts, and
washers:
1. Check to make sure there are no nicks or burrs on
sealing surfaces of cylinder head or crankcase.
2. If all studs were left intact, go to Step 5. If any studs
were disturbed or removed, install new studs as
described in Step 3. Do not use/reinstall any
loosened or removed studs.
3. Install new mounting stud(s) into crankcase.
a. Thread and lock two mounting nuts together on
smaller diameter threads.
24 690 30 Rev. G
1 3
4 2
2
KohlerEngines.com
b. Thread opposite end of stud with preapplied
locking compound into crankcase until specifi ed
height from crankcase surface is achieved.
When threading in studs, use a steady tightening
motion without interruption until proper height is
obtained. Otherwise, frictional heat from
engaging threads may cause locking compound
to set up prematurely.
Studs closest to lifters must have an exposed
height of 75 mm (2 15/16 in.).
Studs furthest from lifters must have an exposed
height of 69 mm (2 3/4 in.).
c. Remove nuts and repeat procedure as required.
4. Install cylinder head. Match numbers on cylinder
heads and crankcase. Make sure head is fl at on
gasket and dowel pins.
5. Lightly lubricate exposed (upper) threads of studs
with engine oil. Install a fl at washer and nut onto
each mounting stud. Torque nuts in two stages; fi rst
to 16.9 N·m (150 in. lb.), fi nally to 35.5 N·m
(315 in. lb.), following sequence shown.
Install Push Rods and Rocker Arms
NOTE: Push rods should always be installed in same
position as before disassembly.
NOTE: Two diff erent screws have been used to secure
rocker arms/pivots. Black screws are used with
heads that have a rocker pivot hole depth of
approximately 21 mm (0.83 in.). Silver screws
are used with heads that have a rocker pivot
hole depth of approximately 35 mm (1.38 in.).
Early models used hollow push rods with special rocker
arms. They are not interchangeable with later/current
style solid push rods and associated rocker arms. Do
not mix these. A replacement kit is available with solid
components.
1. Note mark or tag identifying push rod as either
intake or exhaust and cylinder 1 or 2. Dip ends of
push rods in engine oil and install, making sure each
push rod ball seats in its hydraulic lifter socket.
2. Apply grease to contact surfaces of rocker arms and
rocker arm pivots. Install rocker arms and rocker arm
pivots on one cylinder head, and start two screws.
3. Torque black screws to 18.1 N·m (160 in. lb.).
Torque silver screws to 13.6 N·m (120 in. lb.).
Repeat for other rocker arm.
4. Use a spanner wrench or rocker arm lifting tool to lift
rocker arms and position push rods underneath.
5. Repeat above steps for remaining cylinder. Do not
interchange parts from cylinder heads.
6. Rotate crankshaft to check for free operation of
valve train. Check clearance between valve spring
coils at full lift. Minimum allowable clearance is
0.25 mm (0.010 in.).
Check Assembly
Rotate crankshaft a minimum of two revolutions to check
longblock assembly and overall proper operation.
Reassembly
79