Sknour
Coolants
All water-cooled car and truck engines need coolant so as not to overheat while running. The coolant helps the engine regulate heat and protects against frost. In addition, the coolant protects the cooling system from corrosion.
Coolant must be topped up and completely replaced on a regular basis.
The vast majority of coolants are based on ethylene glycol with the exception of our product P-Glycol. P-Glycol is based on propylene glycol and is recommended for boat engines and applications with a higher risk of leakage into the environment. In addition to ethylene or propylene glycol, the coolant contains inhibitors that protect the engine from corrosion.
Coolant must be topped up and completely replaced on a regular basis. How often you should change the coolant is indicated on the glycol label and data sheet. The vehicle owner’s manual contains information about when to replace the coolant and what type of coolant to use.
The boiling point of cooling liquid increases when the proportion of coolant agent is raised. At the level of air pressure present at sea level, pure water has a boiling point of 100 °C. For pure coolant agent based on monoethylene glycol, the boiling point is over 160 °C. The proportion of coolant agent therefore has a considerable influence on the boiling point of the cooling liquid. This means that the cooling liquid will only reach the boiling point at considerably higher temperatures in accordance with the proportion of coolant agent. This acts as a safety reserve in order to prevent cavitation on the engine components. The operating pressure in the cooling system (approx. 1 bar) further increases the boiling point.
The graphic shows the vapour pressure curves of certain glycol/water mixtures. The resulting boiling points can be read out at the respective intersections, for example at a operating pressure of 1 bar in the cooling system and with various mix ratios.
* In the case of used vehicles (facility vehicle) that were sold from temperate latitudes to hot climate zones, the size of the vehicle radiator may need to be adjusted in accordance with the manufacturer‘s instructions in order to prevent the engine from overheating. This is something that cannot be effectively prevented by operating the cooling system with pure water and/or with the thermostat removed.
Corrosion protection of
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The most important task of the coolant agent is to protect the cooling system against corrosion, which primarily affects the durability of the entire engine.
Coolant must be topped up and completely replaced on a regular basis.
Due to a lack of corrosion-inhibiting substances in the cooling liquid, the salts and acids that may be present in the cooling liquid lead to components being chemically attacked (corrosion). In the long term, this deteriorates the engine components. Aluminium corrosion is a common problem in cooling systems in particular.
The oxygen present in the water also oxidises with ferrous materials and pollutes the cooling liquid with solids (rust). The relatively hard rust particles lead to rapid wear on the sliding ring seal of the water pump.
In order to counteract the corrosion, the coolant agent has alkaline properties. The pH value is around 8, providing a buffer effect with regard to acids that enter the cooling system. The buffer effect is decreasing
over time. Salty water, rainwater, deposits of radiator decalcifiers or combustion gases that enter the cooling liquid can move the ratio of acids to bases into the acidic range. Pure (distilled) water has a pH value of 7 and therefore features neutral properties.
The graphic shows the individual pH value range covered by the various example liquids.