Install Piston Rings - Kohler K91 Service Manual

Some important points to remember when servic­
ing piston rings :
1 If the cylinder block does not need reboring
.
and if the old piston is within wear l imits (refer
to Section 1 , General Information " ) and free
. .
of score or scuff marks , the old piston may be
reused .
2 . Remove old rings and clean u p grooves . Never
reuse old rings .
3 . Before installing new rings o n piston , place top
two rings, each in turn, into its running area in
cylinder bore and check end gap (see Figure
1 1 -1 1 ) .
Model
New
K9 1 , K 1 6 1 , . 007/ . 0 1 7 *
K1 81
K241 , K301 , . 0 1 0/ . 02 0
K32 1 , K34 1
" On M odel K1 8 1 using piston style C or D,
New . 0 1 0/ . 023 , Used . 01 0/ . 032 .
Fig u re 1 1 -1 1 . Measuring Piston Ring E n d Gap .
4 . After installing t h e new compression (top and
middle) rings o n piston , check piston-to-ring
side clearance . Maximum recommended side
clearance is . 00 6 " .
than . 006" , a new piston must be used . Refer
to Figure 1 1 -1 2 .
1 1 . 1 0
E n d Gap
Used
. 007/ . 02 7 "
. 0 1 01 . 030
If side clearance is greater
Fig u re 1 1 -1 2. Measuring Piston Ring Side
Clearance.
Oil Ring End Gaps
Although 4 sizes of service ring sets are available
(Std . , +- . 0 1 0 " , +- . 020, +- . 030 " ) . only two sizes
of oil rings are supplied (Std . and . 020 " oversize) .
When using .01 0 " and . 030 " oversize ring sets ,
the oil rings appear to have excessive end gap .
This is not detrimental and proper sealing will be
achieved d ue to the additional scraper rings and
expander.
NOT E : Scraper and main ring end gaps should be
staggered around the groove to prevent combus­
tion blow-by.

Install Piston Rings

NOTE: Rings must be installed correctly. Ring in­
stallation instructions are usually included with new
ring sets. Fellow instructions carefully . Use a pis­
ton ring expander to inStall rings . I nstall the bottom
(oil control) ring first and the top compression ring
last .
POSI-LOCK CONNECTIN G RODS
Posi-Lock connecting rods are used in some K­
Series engines . On model K1 8 1 engines with the
style D pistons (refer to .. Piston and Rings , Identifi­
cation " earlier in this section ) , the connecting rods
have a narrower piston pin end than on the earlier
(style A) Posi-Lock connecting rods (refer to Fig­
ure 1 1 - 1 3) . Therefore , the Posi-Lock connecting
rods used with the style D piston s " are not inter­
changeable with the Posi-Lock connecting rods
used with style A pistons .