Kohler K91 Service Manual page 104

All parts should be thoroughly cleaned . Dirty parts
cannot be accurately gauged or inspected properly
for wear or damag e . There are many commer­
cially available cleaners that quickly remove
grease , oil and grime accumulation from engine
parts . If such a cleaner is used , follow the
facturer's instructions carefully,
all of the cleaner is removed before the engine is
reassembled and placed in operation . Even small
amounts of these cleaners quickly break down the
lubricating properties of engine oils .
Refer to TP-2 1 50 , A Guide to Engine Rebuilding , for
additional information . Also available is TP-2 1 59 ,
Measurement Guide , which you can use t o record
your i nspection results .
FLYWHEEL
Inspection
Inspect the flywheel for cracks , and the flywheel
keyway for damage. Replace flywheel if cracked .
Replace the flywheel , the crankshaft, and the key
if flywheel key is sheared or the keyway is dam­
aged .
Inspect ring gear for cracks or damage. Kohler no
longer provides ring gears as a serviceable part.
Replace flywheel if the ring gear is damaged .
FLYWHEEL K EY
Inspection
Shearing has been reported specifically on engines
with flywheel drives and battery ignition systems.
Check conditions such as overload , ignition timing
and spark plug gap when flywheel keys hearing oc­
curs.
Spark plug gap on battery ignition engines must be
set as specified . If improperly gapped , a maverick
spark can occu r , which can cause improper igni­
tion of unburned gases and can create a force
causing the flywheel key to shear.
When repairing this type of failure , replace the
flywhee l , crankshaft , key, flywheel washer and nut
or bolt.
SECTION 1 1
I NSPECTION AN D REPAIR
manu­
and make sure that
CYLINDER HEAD
Inspection
Blocked cooling fins often cause localized .. hot
spots " which can result in a " blown " cylinder head
gasket. If the gasket fails , h igh temperature gases
can burn away portions of the aluminum alloy
head . A cylinder head in this condition m ust be
replaced .
If the cylinder head appears in good condition , use
a block of wood or plastic scraper to scrape away
carbon deposits . Be careful not to nick or scratch
the aluminum , especially in gasket seating area .
The cylinder head should also be checked for flat­
ness . Use a feeler gauge and a surface plate or a
piece of plate glass to make this check. Cylinder
head flatness should not vary more than
it does, replace the cylinder head . Refer to Figure
1 1 -1 .
Apply Slight
Downward
Figure 1 1 - 1 . Checking Cylinder Head Flatness.
NOTE : Measure cylinder head flatness between
each cap screw hole.
I n cases where the head is warped or burned, it
will also be necessary to replace the head screws .
The high temperatures that warped or burned the
head could have made the screws ductile which
will cause them to stretch when tightened .
. 003" ; if
1 1 . 1