Generac Power Systems GTV99O User Manual

SECTION
12:
PISTON, RINGS
& CONNECTTNG
ROD tNSpECTtON
& ASsEMBLy
SEcTION
CONTENTS
PAGE
GENERAL
TNFORMAT/ON..._..........................................
12_l
DISASsEMBLE
PISTON AND
CONNECTING
ROD
....,.....
12,]
cHECKTNG
ptSTON
AND
R]NGS................................_...
12,1
CHECKING PISTON
PIN AND
CONNECTING
ROD
.... 12
2
ASSEMELE
ptSTON
AND
CONNECTTNG
ROD ................
12
2
AsSEMBLE
PJSTON
RTNGS
TO
ptSTON
.................
. 12,3
GENERAT
INFORMATION
It is recommended
that new
piston
rings
be innalted
when-
ever the
engine is disassembled
for
rnajorservicing
or overnaur,
provdr,rg
thar
ryhnde
bo.es
are wtl
ir
sperrfrcation.
Remove
any
carbon or ridge
atthe
top of
the cylinder
bore.
This
will
prevent
breaking
the ringswhen
removingthe piston
and connecting
rod from
the
engine. Remove
the
connedring
rod
cap. Push
the
piston
and
connecting
rod
out through
the
top
of the cylinder
Measure
cylinder bores
before
checking
pistons
and ringr.
see Sedion
10.lf cylinder
bor€s
are outoftolerance,
it willnot
be necessarytoaheck pistonsand
rrngssince
a newcrankcase
and
piston
assemblies
willbe
used.
ll
the cylinder
bore is more
than
.075 mm
{.003,)
oversize,
or .035 mm
(.0015")
out of round,
it must
be replaced.
DISASSEMBLE
PISTON
AND
CONNECTING
ROD
1. Remove
piston
rings
using
ring expander.
a. fhen remove
oil ring.
Figurc
t2-t. Renove
Rjngs
2.
Disassemble
piston
from
connecting
rod,
Figure
t2-2.
a Remove
piston
pin
locks.
b. Piston
pin
is a
slip fit in
prston
and
connecting
rod.
Keep
pGtons
and connecting
rods
together
as an
assembly
Do not mix,
Figurc
12-2,
Remove
pistoD
pin
Lock
CHECKING
PISTON
AND
RINGS
lf
the cylinderis
not
goingto
be replaced
andthe prnon
snows
no signs
of scoring,
the
piston
should
be
checked.
Carefully
remove
ca|bon from
ring
grooves.
1. Checkside
clearance
of ring
grcoves
using new
rjngs, Figure
I
2-3.' a 0.1omm
(
004"\
feeter gduge
fo.
t're
(
ompres\ion
ngs
or 0.20mm
(.008")
for
the
ojlring
can be tnseneo,
tne
flng
groove
|5 worn.
The
piston
must be replaced.
Figurc
12-3. Check
Ring
crcoves
2. Check ring
end
gap,
Figure 12-4.
a. Clean
c.|bon from
end of rings
and
insert
approximatety
1
{25
firm)
into
cyllnder
Reiect Dimension (comqession
ngs):.020" (O.S1mm)
Reiect
Dimension
(oil
rings): .045"
(1
.1
Snm)
b.lf
gap
is less
than
rejec
dimension,
remove
some
maer
ial'rom
$F
end o.rne
ingtoachever1emini^Jmgap
3. Check
piston
pln
bore,
Figuret2
5.
a. Reptace if
grearer
than
.7886'
(20.03mm)
or
jf
ir
is .OOO5
,,
(01
mm)
out
of round.
t

Generac Power Systems GTV99O Specifications

General

Brand	Generac Power Systems
Model	GTV99O
Category	Engine
Language	English