Spark Plug Inspection And Cleaning - Piper PA-24 Comanche Service Manual

•
•
PIPER COMAl'ICHE SERVICE MANrAL
FIGt'RE 7-17. REMOVING SEIZED SPARK PLrG
~OTE
Spark plugs should not be used if they have been dropped.
d.
Rernov
al of seized spark plugs in the cylinder may be accomplished by application of liquid carbon
dioxide by
a
conical metal funnel adapter with a hole at the apex just large enough to accornodate the funnel
of a (01 bottle. IR ..fer to Figure
i-17.)
When a seized spark plug cannot be removed by normal means. the
funnel adapter is placed
0\
er and around the spark plug. Place the funnel of the C02 bottle inside the funnel
adapter and relea...e the carbon dioxide to chill and contract the spark plug. Break the spark plug loose with
a wrench, A warm cylinder head at the time the carbon dioxide is applied will aid in the removal of an
excessix ely seized plug.
e. Do not allow foreign objects to enter the spark plug hole.
7-51.
Inspection And Cleaning Of Spark Plug.
a, Visually inspect each spark plug for the following non-repairable defects:
I. Severely damaged shell or shield threads nicked up. stripped or cross-threaded.
, Badly battered or rounded shell hexagons.
J
Out-of-around or damaged shielding barrel.
4, Chipped. cracked. or broken ceramic insulator portions.
5. Badly eroded electrodes worn to approximately SOC( 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.
d. Set the electrode gap at .015 to .018 of an inch or if a smoother operation at idle speed and reduced
magneto drop-off is desired. set at ,0 II:( to .022 of an inch. However. with wide gap setting the plugs must
be
...en iced at more trequent intervals. Fine wire platinum or iridium electrodes should be set at
.015
to
.on:
of an inch only.
•
ISSl'[D: 8/18/72
2B17
POWER PLA~T