Piper CHEROKEE WARRIOR PA-28-151 1995 Maintenance Manual page 272

PIPER CHEROKEE WARRIOR SERVICE MANUAL
8-42. INSPECTION AND CLEANING OF SPARK PLUG.
a. Visually inspect each spark plug. Replace any plug found to have one or more of the following
defects.
1. Severely damaged shell or shield threads nicked up, stripped or cross threaded.
2. Badly battered or rounded shell hexagons.
3. Out-of-round or damaged shielding barrel.
4. Chipped, cracked, or broken ceramic insulator portions.
5. Badly eroded electrodes worn to approximately 50% of original size.
b. Clean the spark plug as required, removing carbon and foreign deposits.
c. Test the spark plug both electrically and for resistance.
Plugs with a wide gap setting must be serviced at more frequent
intervals
d. Set the electrode gap at 0.015 to 0.018 of an inch. If smoother operation at idle speed and reduced
magneto drop-off is desired, set gap at 0.018 to 0.022 of an inch.
e. Fine wire platinum or iridium electrodes must be set at 0.015 to 0.018 of an inch
8-43. INSTALLATION OF SPARK PLUGS.
Before installing spark plugs, check that the threads within the cylinder are clean and not damaged.
Ensure the deep socket is properly seated on the spark plug
hexagon. Plug damage could result if wrench is cocked to one
side when pressure is applied.
a. Apply anti-seize compound sparingly on the threads and install gasket and spark plugs. Torque
360 to 420 inch pounds.
b. Carefully insert the terminal insulator in the spark plug and tighten the coupling nut.
8-44. ENGINE LUBRICATION SYSTEM.
8-45. OIL PRESSURE RELIEF VALVE.
Subject engines may be equipped with either an adjustable or non-adjustable oil pressure relief valve.
A brief description of both types follows:
a. Non-adjustable Oil Pressure Relief Valve - The valve is not adjustable; however, the pressure can be
controlled by the addition of a maximum of three STD-425 washers under the cap to increase pressure
or the use of a spacer (Lycoming P/N 73629 or 73630) to decrease pressure. Particles of metal or other
foreign matter lodged between the ball and seat will result in a drop in oil pressure. Disassemble,
inspect, and clean the valve if excessive pressure fluctuations are noted. The oil pressure relief valve
is not to be mistaken for the oil cooler by-pass valve, whose function is to permit pressure oil to
by-pass the oil cooler in case of an obstruction.
Revised: February 28, 1995
NOTE
CAUTION
1L8
Island Enterprises
POWER PLANT