7.1.6. Diagnostics of the engine on a condition of spark plugs

The condition of the engine can be estimated by the form deposits on the insulator of the central electrode.

Check of spark plugs (when the bent shaft of the engine can be scrolled by a starter)

Fig. 7.6. Defect of the insulator

Connect a candle wire of high voltage to the spark plug which is turned out from a head of cylinders. Connect an external electrode (case) of a candle to "weight" (with an arm on the engine), scroll a bent shaft of the engine a starter. If the candle is serviceable, then between electrodes of a spark plug the spark will slip (quite weak as the category passes in the atmosphere at a small gap). If the spark plug is faulty, then the spark will not appear because of leakage of a charge on the insulator of a candle (fig. 7.6).

Check of candle wires of high voltage
Check a cap and isolation of a wire for lack of cracks.

Fig. 7.7. Scheme of measurement of resistance of a candle wire

Measure resistance of a wire (fig. 7.7).

Resistance of a candle wire of high voltage should not be higher than 10 kOhm (BOUGI) or 22 kOhm (R16AIPS) on wire length meter. If resistance of a wire is higher than the specified size, then replace a wire.