Coolant consists of 60% water and 40% low temperature concentrate G12 A8D (low-temperature compound based on ethylene glycol with anti-corrosion additives). This mixture not only ensures the performance of the engine cooling system down to -25°C, but also protects parts from corrosion, especially those made of light alloys. In addition, it prevents the formation of scale and significantly increases the boiling point of the coolant.
Therefore, the content of low-temperature concentrate in the warm season and in countries with a warm climate cannot be reduced by adding water. The proportion of low-temperature concentrate in the solution must be at least 40%.
In severe climates, you can increase the content of G12 A8D concentrate, but not more than 60% (the freezing temperature of the coolant in this case will be about -40°C), since with a higher percentage of low-temperature concentrate, the freezing point will begin to rise and the heat capacity and thermal conductivity of the coolant will deteriorate.
Use only G12 A8D or TL-VW 774 D specification as low temperature concentrate (pay attention to the inscription on the container).
Other concentrates may be primarily more aggressive towards anti-corrosion coatings.
The corrosion of metal parts caused by the concentrate can lead to coolant leakage, which in turn will cause serious engine damage.
When adding coolant, in no case should G12 be mixed with other low-temperature concentrates (and with G11 composition).
The composition of G12 can be identified by the red color of the coolant in the expansion tank. If the coolant in the expansion tank is brown, then G12 is mixed with another low temperature concentrate! In this case, be sure to replace the coolant, as it can cause serious engine malfunctions.
Checking the level and density of the coolant
The expansion tank of the engine cooling system is located in the engine compartment.
The coolant level should only be checked with the engine stopped.
Pic. 2–9. Checking the coolant level in the expansion tank
On a cold engine, it should be between the MIN and MAX marks on the expansion tank; on a warm engine, it should be slightly above the MAX mark (see fig. 2–9).
A hydrometer must be used to check the density.
A significant decrease in the coolant level most likely indicates a violation of the tightness of the seals. In this case, contact a Volkswagen workshop immediately.
In a sealed cooling system, the coolant level can drop when the engine overheats, when the coolant boils and is expelled.
Adding coolant
Stop the engine and let it cool down. Cover the expansion tank cap with a rag and carefully turn it counterclockwise.
If you do not have G12 A8D Low Temperature Concentrate available under the circumstances, do not add another concentrate to the system. In this case, you can add water and, as soon as possible, restore the required composition of the coolant by adding the recommended low-temperature concentrate.
With a large loss of coolant, topping up should be carried out only on a cooled engine in order to avoid damage to it.
Do not fill the coolant above the MAX mark: excess coolant, due to its expansion, will flow out of the cooling system through the safety valve located in the plug.
Screw the cap on the expansion tank securely.
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