Filter
Top Products
20
Engine
Tractors,
Lawn
and
Garden
- 110
and
112
30-2
Cylinder
Head
and
Valves
-
Tecumseh
SM-2059-(Apr-67)
------~--------------------
----------------------
---------------------------
VA
LVE
ANAL
YS
IS
" .
Fig.
2-Leod
Depo
s
its
all
Leaky
Inrok"
Valve
L e
ad
deposits
on
the
intake
valve
consist
mostly
of
lead
and
some
metal
which
comes
from
the
lubricating
oiL
It
is
caused
by
a
small
amount
of
leakage
of
exhaust
gases
back
into
the
intake
port
area.
This
indicates
that
th
e
valve
is
not
seating
properly.
Grind
the
valve
«nd
reface
the
s
eat
to
correct
this
condition.
NOTE:
Be
sure
/.0
coyyecl
I'
al
ee
1.0
lappet
clearance
a/ler
grinding
l'Dll'es.
See
page
,.
'10-8.
Fig.
3-Volvc
Stcm
Corr
osi
ol1
Valve
stem
corrosion
is
caused
by
moisture
finding
its
way
into
the
engin
e.
Moisture
in
the
fuel-ai.r
mixture
can
condense
inside
the
engine
wh
en
the
engine
is
stopp
ed
before
it
has
had
a
chance
to
warm
up
.
Valve
corrosiOll
can
also
occur
during
storage
when
the
engine
has
not
been
run
for
some
tim
'.~
.
Fogging
or
pouring
oil
in
the
combustion
chamber
befor
e
storing
will
prevent
valv
e
corrosion.
Corroded
and
pitted
valve
s
tend
to
coIl
ct
de-
pOSits
which
in
turn
cau
s s
valve
stic
k
in
g. Alw"
ys
replace
badly
corroded
or
pitted
valves
with
new
valves.
"
II'
Fig.
4-Exhoust
Volve
Ru
n
ning
To
o
Hot
Exhaust
va
lv
es
ar
e d
es
i
gne
d
to
function
in
temperatures
ex
ceedi
ng
5000
°
'.
How
ve
r ,
when
operating
at
this
te
mperatur
for
lon
g
period
s of
time,
valve
burnin
g
occur
s.
Tell-t
ale
signs
of
valves
runnin
g
too
hot
is
the
dark
discoloration
of
the
va
lv
e s
tem
d wn
into
the
ar
ea
protected
by
th
e
valv
e g
uide
. Ano
ther
indication
is
dis-
figuration
of
th
e
val
ve
mar
g
in
and
va
lve
face.
Valve
inserts
ma
y
als
o b gill
to
burn
away
.
The
Illost
common
cause
of
an
overheated
engine
and
va
l es
is
p
oo
r coo
ling
due
to d
ir
t or
obstructions
in
s
id
e
th
e i
ntake
shroudin
g. R -
rnove
and
cle
an s
hr
ou
ding
and
a
ll
coo
lin
g
fi
ns
on
the
engin
e
if
this
con
dition
is n
otic
ed. N
OTL
.
Ne v
er
nm
en
gi
ne
with
shrouding
remov
e
d.
Also
check
for
im
pro
pl'r
valve
timing
L·,
ch
e
cking
and
correcting
valve
cl
,':
uance.
Worn
val
ve
gu
ides
or
valve
springs
can
also
cause
overheated
valv
s .
Valves
running
hot
can
also
be
caused
by
i
rnprope1'
spark
plug
or
ove
rheated
spark
plug
s
which
cause
pre-ignition
or
a
lean
fuel
mixtur
e.
Litho
in
U.
S
.A.