Cessna 150M - Oil Temperature Gauge; Oil Pressure Gauge; Trouble Shooting

NOTE
Before replacing a tachometer cable in hous-
ing, coat lower two thirds with AC Type ST-
640 speedometer cable grease or Lubriplate
No. 110. Insert cable in housing as fitr as
possible, then slowly rotate to make sure it
is seated in engine fitting. Insert cable in
tachometer, making sure it is seated in drive
shaft, then reconnect housing and torque to
50 pound-inches (at instrument).
15-37. TROUBLE SHOOTING.
15-35. OIL PRESSURE GAGE.
15-36. DESCRIPTION. The Bourdon tUbe-type oil
pressure gage is a direct-reading instrument, opera-
ted by a pressure pickup line connected to the engine
main oil gallery. The oil pressure line from the in-
strument to the engine should be filled with kerosene,
especially during cold weather operation, to attain
an immediate oil indication.
TROUBLE PROBABLE CAUSE
REMEDY
GAGE
DOES NOT REGISTER. Pressure line clogged.
Check line for obstructions.
Clean
line.
Pressure line broken.
Check line for leaks and damage.
Repair or replace damaged line.
Fractured Bourdon tube.
Replace instrument.
Gage pointer loose on staff.
Replace instrument.
Damaged gage movement.
Replace instrument.
GAGE POINTER FAILS
Foreign matter in line.
Check line for obstructions.
TO RETURN TO ZERO.
Clean line.
Foreign matter in Bourdon
Replace instrument.
tube.
Bourdon tube stretched.
Replace instrument.
GAGE DOES NOT REGISTER
Faulty mechanism.
Replace instrument.
PROPERLY.
GAGE HAS ERRATIC
Worn or bent movement.
Replace instrument.
OPERATION.
Foreign matter in Bourdon
tube .•
Replace instrument.
Dirty or corroded movement.
Replace instrument.
Pointer bent and rubbing on
Replace instrument.
dial, dial screw or glass.
Leak in pressure line.
Check line for leaks and dam-
age.
Repair or replace
damaged line.
15-38. OIL TEMPERATURE GAGE.
15-39. DESCRIPTION. The oil temperature gage is
a Bourdon-type pressure instrument connected by
armored capillary tubing to a temperature bulb in the
engine. The temperature bulb, capillary tube and
gage are filled with fluid and sealed. Expansion and
contraction of fluid in the bulb with temperature
changes operates gage. Checking capillary tube for
damage and fittings for security is the only mainte-
nance required. Since the tube's inside diameter
is quite small, small dents and kinks which would be
quite acceptable in larger tubing may partially or
completely close off capillary, making gage inopera-
tive.
Change 1
15-15