Piper Navajo PA-31 Service Manual page 512

PIPER NAVAJO SERVICE MANUAL
90 psi, stop engine, loosen the adjusting locknut, and back off the adjusting screw
one or two full turns.
Tighten locknut and retest.
b. 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.
8-72. OIL SCREEN. The suction screen located in the left side of the engine
sump should be cleaned at each oil change to remove any accumulation of sludge
and to examine for metal filings or chips.
If metal particles are found in the
screen, the engine should be examined for internal damage. The suction screen
is removed from the sump by removing the hex head plug at the lower left side
of the sump.
Clean and inspect the screen and gasket and replace the gasket if
over compressed or damaged.
8-73. OIL FILTER ELEMENT.
a. The oil filter element should be replaced after each fifty hours of engine
operation; this is accomplished by removing the lockwire from the bolt-head at
the end of the filter housing, loosening the bolt, and removingthe filter assembly
from the adapter.
b. Before discarding the filter element, remove the outer perforated paper
cover, and using a sharp knife, cut through the folds of the element at both ends,
close to the metal caps. Then, carefully unfold the pleated element and examine
the material trapped in the filter for evidence of internal engine damage such as
chips or particles from bearings. In new or newly overhauled engines, some small
particle of metallic shavings might be found; these are generally of no consequence
and should not be confused with particles produced by impacting, abrasion or pres -
sure. Evidence of internal engine damage found in the oil filter justifies further
examination to determine the cause.
c. After the element has been replaced, tighten the attaching bolt within 20 to 25 foot
pounds torque. Lockwire the bolt through the loops on the side of the housing to the drilled
head of the thermostatic valve. Be sure the lockwire is replaced at both the attaching bolt head
and the thermostatic oil cooler by-pass valve. Refer to the latest revision of Lycoming Service
Letter No. L157.
Revised: 9/24/81
POWER PLANT
2J14