Maintenance

The spark plugs are installed in series and may be of the surface discharge type with four peripheral points and one central electrode or of the type with one peripheral point and one central electrode.

The distance between electrodes on the first type does not need to be adjusted, but on the second a precise measurement must be maintained.

1. Ceramic
2. Gasket
3. Electrode

Maintenance

Periodically check to see if the electrode is dirty. Also check to see if it is worn or the ceramic insulation broken.

Replace the spark plug if any of these faults are detected.

When refitting, lubricate the threads using ISECO MO-LYKOTE A oil and tighten the spark plugs to a torque of:

28 - 34.6 Nm
2.85 - 3.5 kgm

CAUTION Do not use spark plugs of a type or size different from those specified as this may cause damage to the engine and alter the level of toxic exhaust fumes.

CAUTION A dirty or burnt out spark plug is often symptomatic of a malfunction in the engine's supply system.

For example:

• Traces of carbon powder: incorrect mixture, air cleaner very dirty;
• Oil stains: infiltrations of oil from the piston rings;
• Ash formation: presence of aluminium material especially in oil;
• Melted electrodes: overheating due to unsuitable combustion, valve defects.
• Fast-wearing electrodes: damaging additives present in the fuel or oil, pinging, overheating;

For greater detail regarding these problems refer to the fault diagnosis contained in GROUPS 01 and 04.