8.5.3.5. Spark plugs

Or polluted before test clear spark plugs with a deposit on special installation by a stream of sand and blow compressed air. If a deposit of light brown color, then it can be not deleted as it appears on the serviceable engine and does not break work of system of ignition.
After cleaning examine candles and adjust a gap between electrodes. If on the insulator of a candle there are chips, cracks or welding of a side electrode is damaged, then replace a candle.
The gap between electrodes of spark plugs has to be within 0,5–0,6 mm for usual system of ignition and 0,7–0,8 mm — for contactless. Check a gap the round wire probe. It is impossible to check a gap the flat probe as at the same time dredging on a side electrode which is formed during the work of a candle is not considered. Regulate a gap a podgibaniye only of a side electrode of a candle.
Test for tightness. Screw a candle in the corresponding nest at the stand and tighten a dynamometer key the moment 31–39 N · m (3,2–4 kgfs · м). Create pressure of 2 MPas (20 kgfs/cm2) in the camera of the stand. Drop from a butterdish on a candle several drops of oil or kerosene; if tightness is broken, then there will be vials of air, usually between the insulator and the case of a candle.
Electric test. Screw a candle in a nest at the stand and tighten the moment stated above. Adjust a gap between rated sportsman electrodes on 12 mm that corresponds to voltage of 18 kV, and then the pump create pressure of 0,6 MPas (6 kgfs/cm2). Establish a tip of a wire of high voltage on a candle and give on it impulses of high voltage.
If in an eyepiece of the stand the full-fledged spark between candle electrodes is observed, then the candle is considered excellent. If sparking happens between rated sportsman electrodes, then it is necessary to lower pressure in the device and to check with what pressure there occurs sparking between candle electrodes. If it begins with a pressure below 0,3 MPas (3 kgfs/cm2), then a candle defective.
Several sparking on a rated sportsman is allowed. If sparking is absent on a candle and on a rated sportsman, then it must be assumed that on the insulator of a candle there are cracks and that the category happens inside, between the weight and electrodes. Such candle is discarded.