G643(E) Service Manual Chapter 4. Engine Electrical System 116
Spark Plug Inspection
(3) Spark plug.
4. During installation of the spark plug wires,
makesure the wire terminals make good
connections inthe distributor cap and on the spark
plugs. Inspectspark plug (3) insulator for cracks.
Clean the sparkplug of any oil or dirt before
installation.
Inspection of Spark Plug Wires
General Description
The spark plug wires are a carbon-impregnatedcord
conductor encased in an 8 millimeter diameter
silicone rubber jacket. Silicone wiring will withstand
very high temperature and is an excellent insulator
for the higher voltages.
Silicone is soft, pliable, and therefore, more
susceptible to scuffing and cutting. It is extremely
important that the spark plug cables be handled with
care. They should be routed so as not to cross
each other, or be in contact with, other parts of the
engine to prevent rubbing.
NOTICE: For proper operation, it is necessary to
keep ignition wires and distributor clean and free of
any dirt or corrosion.
Resistance Testing
1. Disconnect both ends of ignition cable (rotate
boot and pull at the boot only) being tested and
clean terminals.
2. Set ohmmeter on high scale and connect
ohmmeter to each end of cable being tested.
Twist cable gently while observing ohmmeter.
3. If ohmmeter reads above 25,000 ohms or
flucuates from infinity to any value, replace cable
being tested.
4. If the resistance of each cable is not within the
following bands, replace the cable being test-ed.
0 to 15 inch cable................. 3,000 / 10,000 Ohms
15 to 25 inch cable............... 4,000 / 15,000 Ohms
25 to 35 inch cable............... 6,000 / 20,000 Ohms
Spark Plug Wire Routing
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