b. Adjustable oil Pressure Relief Valve. The adjustable oil pressure relief valve enables the operator to
maintain engine oil pressure within the specified limits (refer to the engine manufacturer's appropriate manual).
The valve is located above and to the rear of No. 3 cylinder. If the pressure under normal operating conditions
should consistently exceed 90 psi., or run less than 60 psi., adjust the valve as follows:
With the engine thoroughly warmed up and running at a maximum of 2200 RPM, observe the reading on
the oil pressure gauge. If the pressure is above 90 psi, stop engine, loosen the adjusting locknut; and back off the
adjusting screw one or two full turns. Tighten locknut and retest. If pressure is too low, turn adjusting screw
further into the relief valve plug, thereby increasing the tension on the relief valve spring. When the valve has
been satisfactorily adjusted, tighten the locknut and lockwire the crown nut to the drilled ear projecting from the
valve mounting boss.
8-43. CARBURETOR ICE DETECTOR.
The operational carburetor ice detection system used on the PA-28-161 CADET utilizes an optical probe
installed in the carburetor throat, just upstream of the throttle valve. As ice forms and blocks the passage of light
within the probe, the warning is triggered. When the ice has melted and enough light is sensed, the warning light
will be extinguished. The probe has an expected service life of 50,000 hours. A built in test circuit is activated
such that each time the switch is turned on the light will come on momentarily.
8-44. REMOVAL OF ICE DETECTOR PROBE.
a. Remove the engine cowl.
b. The probe is mounted in the carburetor or just below the throttle valve control arm. Remove the safety
wire and carefully unscrew the probe from the carburetor. Measure and note how far the probe extends into the
carburetor.
c. Where the wires for the probe come off the engine mount remove the wire insulation sleeves; make note of
the respective wire interconnects; and, disconnect the wires.
d. If the engine is to be operated, install a suitable blanking plug.
8-45. INSTALLATION OF ICE DETECTOR PROBE.
a. If a blanking plug has been installed, remove the plug from the carburetor housing. The probe is mounted
just below the throttle valve on the left side of the carburetor.
—CAUTION—
Do not bend the probe components.
b. Carefully screw in the probe. When installed, the index mark on the probe housing should face towards
the carburetor air inlet. If necessary use AN960-416L shim washers to position the probe properly.
c. Tighten the probe as much as possible by hand, and then, only a quarter turn more using a 3/8 inch short
handle open end wrench.
d. Connect the appropriate wires and position the sleeves over the connectors. If heat shrink has not been
used, tie with #6 electrical lacing wire.
PIPER AIRCRAFT
PA-28-161 CADET
AIRPLANE MAINTENANCE MANUAL
Issued: FEBRUARY. 28, 1989
POWER PLANT
1K12
