3.9. Check of technical condition of the engine

Technical condition of the engine is defined by fuel consumption, engine capacity, oil pressure, a compression in cylinders, noise of operation of the engine and smoke of an exhaust.
Measure control fuel consumption on the car (after the run not less than 9 000 km) moving on the highest transfer with full loading on the dry flat asphalted or concrete road with a speed
90 km/h. Peredny Bridge has to be disconnected at the same time.
You carry out measurement on the section of the road 3-5 km long in two opposite directions. Before arrival warm up the engine and units of the chassis a run of the car of 10-15 km.
It is possible to apply a tank of the GARO model 361 to measurement of fuel consumption.
During the winter period control fuel consumption can increase no more than by 10%.
Power qualities of the engine are determined by dispersal and the largest speed of the car.
Determine technical condition of units of the chassis by the size of a way of free "vybeg" of the car. On the flat section of the asphalted highway at the movement with the established speed of 50 km/h switch off transfer and let's the car move quietly to a full stop. You make measurement of a way of free "vybeg" at arrivals in two opposite directions.
You carry out check of control fuel consumption and "vybeg" of the car at normal, on external signs, operation of the engine. Before it check and if necessary adjust pressure in tires, a convergence of forward wheels, completeness of a disinhibition of brake mechanisms. Wear of a protector of tires has to be no more than 50%.
The running gear is in good repair if the car (after the run of 9000 km) moves to a full stop not less than 400 m.
The oil consumption in use the engine does not remain to constants: in the course of a running in it decreases and after the run of 5 000-7 000 km there are equal 70–150 g on 100 km of a run. After the run of 70 000-90 000 km the consumption of oil increases. If the consumption of oil exceeds 450 g on 100 km of a run, then the engine demands repair. You make measurement of a consumption of oil by method of a doliv.
Check oil pressure in lubricant system the control manometer with the division price no more than 49 kPa (0,5 kgfs/cm2) which is connected by means of a flexible hose instead of the oil pressure sensor. For measurement of pressure of oil on the standing still car lift the back bridge on supports, switch off the forward bridge, launch the engine and, having included direct transfer, open by means of the manual drive a butterfly valve of the carburetor so that the speedometer showed the speed of 45 km/h, and measure pressure in system.

Fig. 2.39. Check of a compression in engine tsilind-ra

Check a compression in cylinders on the heated-up engine kompressometry the GARO model 179. For this purpose turn out spark plugs, insert a rubber conical tip of a kompressometr into an opening for a candle (fig. 2.39) and a starter turn a bent shaft at completely open butterfly valve and the carburetor without fuel. Pressure in cylinders has to be not less than 660 kPa (6,65 kgfs/cm3). The difference of pressure in cylinders should not exceed 98 kPa (1 kgf/cm2).
Evenly lowered compression in all cylinders testifies, as a rule, to considerable wear of cylinders and piston rings. Decrease in a compression in separate cylinders can result from "lag" or a burn-out of valves, burning or breakage of piston rings, damage of laying of a head of the block of cylinders or violation of adjustment of gaps to the valvate mechanism. If when filling 25 - 30 cm3 of pure oil in the engine cylinder with the lowered compression pressure in it increases, then it demonstrates breakage of piston rings or their coking up in piston flutes. If at the same time the compression does not increase, then the cause of defect needs to be looked for in leakage, lag and an obgoraniye of valves or in damage of laying of a head of the block of cylinders.
Decrease in a compression in two next cylinders indicates damage of laying of a head of the block of cylinders.

Fig. 2.40. Zones of listening of the engine:
1 – gear wheels distributive; 2 – valves;
3 – fingers piston; 4, 5 – pushers, bars of valves, bearings of a distributive shaft; 6 – bearings radical bent shaft

Listen to knocks and noise of the engine a stethoscope of the K-69M GARO model on the heated-up engine with various frequency of rotation of a bent shaft (fig. 2.40).
Begin listening with the distributive mechanism at a small and average frequency of rotation of a bent shaft: valves at 550–1000 min.-1, pushers at 1000–1500 min.-1, distributive gear wheels at 1000 - 2000 min.-1.
Knocks of valves are clearly listened from a head, over the locations of valves; knocks of pushers and necks of the camshaft – from an arrangement of the distributive mechanism, at the level of a camshaft axis; knocks of distributive gear wheels – from a cover.
Krivoshipno-shatunny wiretap the mechanism (pistons and radical bearings) at sharp change of frequency of rotation of a bent shaft of the engine within 500–2500 min.-1.
For definition of the cylinder in which there are knocks of the krivoshipno-conrod mechanism serially remove from wire candles.
Most clearly knocks of bearings are listened on case walls on the right side at the level of the camshaft; knocks of pistons and piston fingers – on cooling shirt walls against the corresponding cylinders.
Knocks of radical bearings – deafs, and knocks of conrod bearings and piston fingers – sharper and ringing. Knocks of pistons – sharp, jingling. They can be listened on all power setting.
Knocks of pistons, piston fingers, radical and conrod bearings, valves and pushers on the heated-up engine testify to malfunction of the engine.
The increased knock of valves and pushers merging in the general noise of the engine at increase in frequency of rotation of a bent shaft or the periodic knock of valves appearing and disappearing at sharp change of frequency of rotation of a bent shaft, and also insignificant knock of pistons on not heated-up engine are not signs of malfunction of the engine. Let's allow also insignificant noise of high-pitch tone from work of distributive gear wheels and gear wheels of the oil pump.