Cessna T188C - Manifold Pressure Gage; Tachometer; Description

MODEL
188
& T188
SERIES
SERVICE
MANUAL
15-19.
ENGINE
INDICATORS.
NOTE
Before replacing
a tachometer cable in
hous-
15-20.
TACHOMETER.
ing,
coat
lower
two
thirds
with
AC
Type
ST-
640 speedometer
cable
grease
or Lubriplate
15-21.
DESCRIPTION.
The
tachometer
is
a me-
No.
110.
Insert
cable
in housing
as
far
as
chanical
indicator
driven
at half
crankshaft
speed
by
possible,
then
slowly
rotate
to
make
sure
it
a
flexible
shaft.
Most
tachometer
difficulties
will
be
is
seated
in the
engine
fitting.
Insert
cable
found
in
the drive-shaft.
To
function
properly,
the
in tachometer,
making
sure
it is
seated
in
shaft
housing
must
be
free
of kinks,
dents
and
sharp
drive
shaft,
then
reconnect
housing
and
torque
bends.
There
should
be
no
bend on
a radius
shorter
to
50 pound-inches
(at instrument).
than
six inches
and
no
bend within
three
inches
of
either
terminal.
If
a tachometer
is
noisy
or the
15-22.
MANIFOLD
PRESSURE
GAGE.
pointer
oscillates,
check cable
housing for kinks,
sharp
bends
and
damage.
Disconnect
cable
at tach-
15-23.
DESCRIPTION.
The manifold
pressure
gage
ometer
and
pull it
out
of housing.
Check
cable
for
is a
barometric
instrument
which
indicates
the
ab-
worn
spots,
breaks
and
kinks,
solute
pressure
in
the
intake
manifold
in inches
of
mercury.
The fuel
flow
and manifold
pressure
indi-
cators
are
in one
instrument
case,
however,
each
instrument
operates
independently.
15-24.
TROUBLE
SHOOTING.
TROUBLE
PROBABLE
CAUSE
REMEDY
EXCESSIVE
ERROR AT
EXISTING
Pointer shifted.
Replace
instrument.
BAROMETRIC
PRESSURE.
Leak
in vacuum
bellows.
Replace
instrument.
Loose
pointer.
Replace
instrument.
Leak
in pressure
line.
Repair
or
replace
damaged
line,
tighten
connections.
Condensate
or fuel
in line.
Blow out
line.
JERKY
MOVEMENT
OF
Excessive
internal
friction.
Replace
instrument.
POINTER.
Rocker
shaft
screws
tight.
Replace
instrument.
Link springs
too
tight.
Replace
instrument.
Dirty
pivot bearings.
Replace instrument.
Defective mechanism. Replace instrument.
Leak
in pressure
line.
Repair
or replace
damaged
line,
tighten
connections.
SLUGGISH
OPERATION
OF
Foreign
matter in
line.
Blow
out line.
POINTER.
Damping
needle dirty.
Replace instrument.
Leak in
pressure
line.
Repair or
replace
damaged
line,
tighten connections.
EXCESSIVE
POINTER VIBRA-
Tight rocker pivot bearings.
Replace
instrument.
TION.
Excessive
panel
vibration.
Replace
defective
shock
panel
mounts.
15-8