Useful tips for engine diagnostics (Renault Logan 1)

With a certain amount of skill and attentiveness, many engine and system faults can be determined quite accurately by the color of the smoke coming out of the exhaust pipe. Blue smoke indicates oil getting into the combustion chambers, and constant smoking is a sign of severe wear of the cylinder-piston group parts. The appearance of smoke during revving, after prolonged cranking by the starter, after long idling or immediately after engine braking usually indicates wear of the valve stem seals. Black smoke is an overly rich mixture due to a faulty engine management system or injectors. Gray or thick white smoke with an admixture of moisture (especially after the engine overheats) means that the coolant has entered the combustion chamber through a damaged cylinder head gasket. If this gasket is severely damaged, the liquid sometimes enters the oil pan, the oil level rises sharply, and the oil itself turns into a cloudy whitish emulsion. White smoke (steam) from an unheated engine in damp or cold weather is normal.

Quite often you can see a car standing in the middle of a city traffic jam with the hood open, emitting clouds of steam. Overheating. Of course, it is better not to allow this, looking at the temperature gauge more often. But no one is immune from the fact that the thermostat, electric fan may suddenly fail, or the coolant may simply leak. If you missed the moment of overheating, do not panic and do not aggravate the situation. Overheating is not as scary as its possible consequences. Never turn off the engine immediately - it will get a heat stroke and, perhaps, after cooling down, will refuse to start at all. After stopping, let it run at idle speed, while the circulation of liquid in the system will remain. Turn on the heater at maximum power and open the hood. If possible, pour cold water on the radiator. Only after achieving a decrease in temperature, stop the engine. But never immediately open the radiator cap: on an overheated engine, a geyser from under the open cap is guaranteed. Take your time, let everything cool down, and you will save the health of the machine and your own health.



Almost all car manuals recommend that the clutch must be depressed when starting the engine. This recommendation is only justified in the case of starting in severe frost, so as not to waste battery energy on turning the shafts and gears of the gearbox in thickened oil. In other cases, this measure is aimed only at preventing the car from moving if a gear is engaged due to forgetfulness. This technique is harmful to the engine, since when the clutch is depressed, significant force is transmitted through it to the crankshaft thrust bearing, and when starting (especially cold) lubrication does not reach it for a long time. The bearing wears out quickly, the crankshaft gets axial play, and starting from a standstill begins to be accompanied by strong vibration. In order not to damage the engine, get into the habit of checking the position of the gearshift lever before starting and starting the engine with the handbrake applied, without squeezing the clutch unless absolutely necessary.

Material is located on the source website: RenaultBook