Технические науки/ Транспорт

Spektoruk S.A.

Kostanay State University, Kazakhstan

The basic malfunctions of cooling system

It is known that technical condition of cooling system is mostly dependents on the reliability and efficiency of engine.

For normal engine work, it is necessary that temperature of coolant in system is maintained within a certain range (thermal mode is within 85-90 ° C) under various conditions.

The need of cooling system repairing arises in such cases as:

- The constant overheating or overcooling of cooling liquid;

- Reduction of a coolant due to leakage;

- Increased noise during operation of liquid pump

- The occurrence of electrolysis in the coolant.

Possible causes and remedies of malfunctions are shown in Table 1

When the engine overheats, combustion of fuel-air mixture breaks; increasing of frictional forces leads to increased fuel consumption and reduced engine power.

By overcooling of liquid, engine power reduces and fuel consumption increases.

In addition, lowering of temperature in cooling system leads to deterioration of pistons and cylinders because of flushing fuel oil from cylinder surface. There is a dilution of the oil fuel, which enters a sump and more intensive formation of resin deposits on the piston rings and pistons. Overcooling of engine is possible in open position of thermostat jamming or in absence of the thermostat, disrepair of electric fan or hydraulic fan.

External signs of cooling system are: external and internal coolant leak.

Driver should always follow to indications of temperature gauge on the dashboard, so as not to miss the fault.

For example, in "Opel" cars, filling capacity is under hood next to engine on the left wing.

Table 1 - Possible causes of engine overheating and repairing methods of defects in cooling system

Possible cause	Repairing method
Low level of coolant Leak of heat transfer agent Full radiator Radiator`s cover malfunction Ventilator defect Thermostat defect Water pump defect	To add To repair To clean To substitute To substitute To substitute To substitute

On the cold engine, liquid level should be slightly above the mark "Kalt" (cold). On the hot engine fluid`s level in the tank rises. By topping up of fluid, one should use the same antifreeze that has been poured into the cooling system. It allows a normal engine work at temperatures down to -25 ° C.

On vehicles with control system coolant level, reducing of level are alerted warning light on the instrument panel.

External leakage is accompanied by appearance of a specific sweet smell of antifreeze and smudges under car and engine.

Internal coolant leaks are not so obvious. Appearance of internal leakage is followed by white smoke (evaporation of cooling liquid) from the exhaust system on warm engine. However, it should be noted that when we warms engine up in cold weather, white smoke is a natural phenomenon.

Internal leakage acts in the same way by presence of oil-water emulsion (foam light color), resulting in a compound of oil and coolant at oil probe. External and internal leaks lead to violation of temperature and engine overheating.

If liquid pump works noisily, one should check its axial backlash. The VAZ cause of the malfunction usually is locked screw incorrectly fixed bearing in the body. Swaying slightly, it makes a sharp sound from friction of outer cage.

To get rid of the sound, you can replace regular locking screw bolt 17 mm long M6 threaded head by a 10 mm wrench. Bolt`s rod is taper grinded, then it is possible to tighten the locking screw with wrench without removing pump`s impeller and pulley`s belt. One of the cooling system`s malfunction is the emergence of electrolysis. Electrolysis is the decomposition reaction of chemical`s materials during the passage through the radiator made of aluminum, and a temperature sensor of fan`s in - thermoswich of electric current. Reasons are blockage of radiator tubes, white fur around his leaky places, greenish deposits near thermoswitch. When at least one of these symptoms are appeared, check connection of electric devices of cooling system.

Particular attention should be paid to the fact that radiators are made of aluminum. It is not recommended to use water as a coolant. The presence of water leads to corrosion of radiator tubes.

Thus, in order to prevent possible defects of engine cooling system, we must remember that pouring cold water into a hot engine is wrong, because it can lead to cracks in the cooling sector of cylinder. After pouring off of coolant, starting and transient operation of the engine are prohibited, because it can lead to destruction of the sealing rubber rings of cylinder, valve seat loss, leads to burning of gaskets and warping units cylinders. Frequent changing of water in the cooling system accelerates a corrosion and scum formation. When radiator`s core is clogged cooling system should be cleaned by water jet or by compressed air directed to the core from fan`s side. In the aim to remove the cooling system scum, rust and sediment, cooling system must be flushed. When level of scum is low, cooling system must be washed by pure water. Cooling system should be washed after running of a new car and seasonal inspection.

Literature:

1. Shestopalov.S The device, service and repair of cars. - Moscow, 2009

2. Chumachenko.Y Smith. -Moscow 2009

3. Bonacz Ray T. Engine Cooling Systems HP1425: Cooling System Theory, Design and Performance For Drag Racing, Road Racing, Circle Track, Street Rods, Musclecars, Imports, OEM Cars, Trucks, RVs and TowVehicles.USA, 2007