Gravely 424 - Page 27

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tow
corvtPxEs3loN
POSSIBLE CAUSX
NEMEDY
A,
B.
C.
'.
Cylinder
head
gasket
blown.
Cylinder
head
warped
or
loose.
Piston
riags
rvorn
-
blowbv occurring.
Valves
leaking.
A. Remove
head, replace
ga;ket,
reinstall
head, re-
check compression.
B.
Remove
head, check
for 0atness
(see
cylinder
head service),
reinstall
and
secure
in
proper
sequenc€
to
specified
torque
value.
C.
Eecondition
engine.
D.
Recondition
engine.
Higher
than normal compression
eaa indicate
that excessive
carbon
deposits
have
bnilt up
in the combustion
chamber.
A simple
"feel"
test
can be
used as a
"spot
check"
if
poor
compression
is suspected
as tlre
reason
for ?rard
starting and
lack of
power.
Il results of test
point
to
poo!
compre:sion
-
this
test should
be follo*'ed up
u'ith
the
more
precise and aceurate
test
me*:od
usir:g
a
conplession
gauge.
METHOD
r
-
SPOT CHECX
WlrHOUl
GAUOE)
Remove high terrsion lead from
the
spark
plug.
On atl
engines,
rotate
flyrvheel
backwards
(counterclockrvise
direction)
against
po\\,er
stroke
-
if
little or no
resistance
is
felt, check
with
compression
gauge.
METHOD
2
_
COiAPTESSION
GAUG:
TEST
A. Remove
spark
plrrg
rrnd insert compressiol
garrge
in hole,
B.
Lngine
rvill
havc
to be rnotored
to a
speed
of about 1000
HPM,
Hold throttle
rvide open
and
take several
ccmpression
readings.
Consistenl readings
of
110 to
l?0
psi
indicate
good compression.
Many
major
engine
repair
operations
can
be done
without removing
the
engine frorn
the
tractor.
Yalve
grind-
ing and
ring
replacement
can
be
done
without
engine lemoval.
Crankshaft
removal
requires
engine
removal.
*e!firvel
NOIE:
$ee
f,gure
30.
Mele stuls
out
of tro
?1lfi
boltt !y removing heads.
Griad wrencli
{qts
or
cut e
screwdriver
slot
ir the
unthrs*ded
tld
o{ stud.
This will
aid:amoval
and
installatiqr
of
the
er$aa.
D:ain oil
*om
traamfusion.
Disco*nect
chqke
(sr*lol
&sm carburetor.
Disconnect
governor
co$trol from
engine,
$hut
off fuel at tant
aad sst {rste
fuel line.
CAUTION;
A
small'atrtount
of
fuel
n,ill
be
spilled
ss tte llrc
is separated,
Remcve
cable
from
positive
(*)
battery
pst.
jtrpvo
cable
frotr: starter
motor'
1,
0
3.
4.
xt
Figure
20