Inside the engines of combustion, the system of refrigeration must fulfill its principal function which is to avoid the excessive heat of the metals that cover the chamber of combustion, if this heat is not controlled, the metals immediately expand its molecules and as consequence of this the lubricating oils will be absorbed provoking the cessation of the engine. Apart, the system of refrigeration must support a minimal and constant temperature since the engine does not work if it is excessively cold or warm.

When we use cooling liquid, the heat produced by the combustion is absorbed by the liquid in the conduits that surround the cylinders, when the liquid goes out of the conduits it cools and returns again to absorb more heat, this constant traffic is the one that supports the ideal temperature in order that they do not present damages in the engine.

The combustion produces temperatures between the 3.092 and 4.532º F. A part of this temperature goes to the walls of the cylinders, of the pistons, the butt and the valves who absorb them, for this is very important that these pieces are refreshed in order that they do not accumulate high temperatures that would damage them and it would affect in the normal functioning of the engine.

The limits of temperature of the previous pieces are the following:

WALLS OF THE CYLINDER: 302 to 392 ºF
If this temperature is not kept the lubricating oil loses properties and this provokes wear beyond the common forming carbonaceous deposits, destruction of the hoops, etc.
PISTON: The top part is the warmest, can come to them 572º F. If the piston is composed of a light alloy it can reduce its mechanical resistance.
VALVE OF LEAK: 1292 to 1382ºF
If this temperature is exceeded its mechanical resistance decreases to the corrosion.
WALLS OF THE CHAMBER OF COMBUSTION: 482ºF.
This one is the ideal temperature that assures the correct dissipation of the heat in the seat of the valves and the candlesticks as well as the correct functioning of the thermal cycle of the engine.

When the engine works with the temperature under normal all the parts that shape it are exposed to the wear and to the corrosion, for this is suitable that the system of refrigeration produces a sufficient, but not excessive cooling, because if the temperature does not reach certain value the fuel not vaporize enough, therefore the mixture is not homogeneous, the combustion is not realized regularly and can happen that the fuel passes between the shirt and the piston diluting the oil of the housing that favors the corrosion; because of it there is recommended that on having ignited the engine it is necessary to him to take to its normal temperature in the minor possible time and support it inside the margins, imports neither the conditions of functioning nor the temperature of the environment.

The conduits of the block of the engine must be completely free of oxide, mineral inlays and gels. There are two different forms from corrosion that can produce fails in the system of cooling. The first one is the oxidation, which can cause loss of the metal until it causes mechanical damages. The second one is the excessive formation of inlays, which are blocking the conduits of the system of cooling, impeding the heat transference, and, finally, obstructing completely the system, causing direct damage that can cause that the engine is founded. In both cases there offers as solution the chemical or mechanical treatment of the system of cooling, but this one is a corrective maintenance that can anticipate if the system is protected to avoid to have to resort to this type of methods, as the chemical washes or the utilization of probes. The chemical corrosion or oxidation is produced, generally, in the radiators and the water bombs. The strong corrosion causes reduction of the flows, escapes about the gaskets, and, in extreme cases, total break of the water pump. The inlays happen when the mineral salts settle on the walls of the conduits of the system of cooling, forming strongly adhered crusts, as hard as rocks, which are closing the conduits up to stopping up them completely.

On the inlay having be formed the diameter is decreased for the flow of the cooling, for what in these sections the fluid passes with major speed, and the contact of the cooling with the engine will last less time, decreasing the removal of the heat. Besides, these inlays act as refractory ceramics, which is very efficient in the thermal isolation of ovens and kitchens, but totally undesirably in the systems of cooling, since it is had less time of contact and the isolation that prevents the heat step does of the inlays a problem of extreme careful.

Another problem that one presents with the systems of cooling consists of the punch of the metallic surfaces for the cavitation of the cooling liquid. The cavitation is a phenomenon of sudden shock of the steams of cooling liquid against the walls of the conduits of the system of cooling that removes the protective cap formed by the chemical additives, which leaves the metal without protection against the wear for flow of the cooling liquid and the oxidation. This problem appears, principally, in the engines constructed with alloys that have high percentage of aluminium and in the engines of heavy work. In the first case its appears due to the fact that the aluminium is a metal that pushes the heat back and, for this, the temperature of the fluid in the nearness of the walls is high than another type of engines doing that the cooling liquid is more inclined to the formation of bubbles for boiling. For the engines of work weighed with design of block of humid cylinders with shirts, the problem appears due to the fact that in the design of humid shirt strong vibration takes place as consequence of the freedom in which they find the connecting-rods in the cylinders of the engine, by what there is recommended the use of a Cooling Complementary Additive for the suitable protection of this type of engines.

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