16
General Information
S27 FE 350 ENGINE
CAUTION
• Before removal and disassembly, clean the engine.
Remove all dirt from plug base in the cylinder head before removing plug. Use a 13/16-inch deep well socket wrench
or 13/16-inch spark plug wrench to loosen the plug.
Spark Plug Cleaning, Inspection and Repair
Examine the plug
. The deposits on the plug base and electrode are an indication of the
correct heat range and efficiency as well as a guide to the general condition of the engine, fuel and air mixture and
ignition system. If all of the above conditions are proper, the spark plug should be a light brown color. There should be
no bridging between the electrode and base. The electrode should not be eroded. Black color, excessive carbon,
and/or a wet plug indicates that the fuel is too rich. White, burned or melted electrodes indicate the fuel is too lean or
pre-igniting. Oily deposits on the plug electrode are an indication of worn rings, valve guides, cylinder wall, etc. Also
examine the spark plug wire. Remove rubber boot and inspect internal spring for damage. Inspect spark plug wire for
damage and be sure spring coil is securely attached to spark plug.
See following WARNING
.
WARNING
• Remove spark plug wire to avoid accidental start up of the engine when servicing vehicle. To avoid
ignition of fuel and serious personal injury or death, never try to start the engine with plug removed
from engine.
A
524
Figure 16-1
Spark Plug
Testing the Spark Plug
Check the sparking ability of a cleaned and properly gapped plug on a sparking comparator if possible. Spark should
be blue and strong and able to jump a 5/16-inch (8 mm) gap.
Setting the Spark Gap
1.
Pass a contact point file between the electrodes to produce flat, parallel surfaces to facilitate accurate gauging.
2.
Use a wire type gauge. Bend the outside or ground electrode so only a slight drag on the gauge is felt when
passing it between the electrode. Never make an adjustment by bending the center electrode. Set gap (A) to
0.027-0.031 inches (0.69-0.79 mm)
Spark Plug Installation
NOTE:
Before installing the plug, check the condition of the threads in the cylinder head. Soften deposits in cylinder
head threads with penetrating oil and clean the threads with a tap if necessary.
Use a high temperature, anti-seize lubricant on the threads of the spark plug to reduce friction when installing
a new plug, and reduce “gauling” and thread seizing for future replacements.
Install the spark plug by threading it in until finger tight, then tighten the spark plug to 20 ft-lb (27 N·m).
Page 16-2
2007-2009 Turf 252, Carryall 252 and XRT 900 Maintenance and Service Manual
