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Introduction
5
Maintenance
The information in this manual applies to the MTD
engine. Some basic principles may apply to engines pro-
duced by other manufacturers.
As the saying goes “an ounce of prevention is worth a
pound of cure”. The same can be said about preventive
maintenance on outdoor power equipment. By changing
the spark plug and oil at recommended intervals many fail-
ures can be avoided.
NOTE: Please refer to Chapter 7: Ignition for the complete
service instructions on spark plugs.
1. The spark plug used in the MTD engine is a F6RTC
gapped to 0.026” - 0.030” (0.65 - 0.75 mm).
See Figure 1.2.
NOTE: The F6RTC plug is the only plug that is EPA certi-
fied for the MTD engine.
2. Wear rate will vary somewhat with severity of use. If the edges of the center electrode are rounded-off, or any
other apparent wear / damage occurs, replace the spark plug before operating failure (no start) occurs.
3. Cleaning the spark plug:
NOTE: MTD does not recommend cleaning spark plugs. Use of a wire brush may leave metal deposits on the
insulator that causes the spark plug to short out and fail to spark. Use of abrasive blast for cleaning
may cause damage to ceramic insulator or leave blast media in the recesses of the spark plug. When
the media comes loose during engine operation, severe and non-warrantable engine damage may
result.
4. Inspection of the spark plug can provide indications of the operating condition of the engine.
• Light tan colored deposits on insulator and electrodes is normal.
• Dry, black deposits on the insulator and electrodes indicate an over-rich fuel / air mixture (too much fuel or
not enough air)
• Wet, black deposits on the insulator and electrodes indicate the presence of oil in the combustion cham-
ber.
• Heat damaged (melted electrodes / cracked insulator / metal transfer deposits) may indicate detonation.
• A spark plug that is wet with fuel indicates that fuel is present in the combustion chamber, but it is not
being ignited.
Figure 1.2
For Parts Call 606-678-9623 or 606-561-4983
www.mymowerparts.com