Table of contents: Checking the coolant level and… ↓ Topping up the coolant ↓
The engine cooling system is filled at the factory with a long-lasting coolant that does not need to be replaced.
The coolant consists of 60% water and 40% low-temperature concentrate G12 A8D (low-temperature composition based on ethylene glycol with anti-corrosion additives). This mixture not only ensures the engine cooling system operates at temperatures down to -25°C, but also protects parts from corrosion, especially those made of light alloys. In addition, it prevents scale formation 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 harsh climate conditions, the G12 A8D concentrate content can be increased, but not more than 60% (the freezing point 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 increase and the heat capacity and thermal conductivity of the coolant will deteriorate.
As a low-temperature concentrate, only G12 A8D or concentrate with specification TL–VW 774 D should be used (pay attention to the inscription on the container).
Other concentrates may be, above all, more aggressive towards anti-corrosion coatings.
Corrosion of metal parts caused by the concentrate may result in coolant leakage, which in turn will cause serious engine damage.
When topping up the coolant, never mix G12 with other low-temperature concentrates (and with the composition G11).
The G12 composition can be determined by the red color of the coolant in the expansion tank. If the coolant in the expansion tank is brown, then the G12 composition is mixed with another low-temperature concentrate! In this case, it is necessary to replace the coolant, as it can cause serious problems with the engine.
Checking the coolant level and density
The expansion tank of the engine cooling system is located in the engine compartment.
The coolant level should only be checked with the engine not running.
Fig. 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).
To check the density, you need to use a hydrometer.
A significant drop in coolant level most likely indicates a leak in the seals. In this case, contact your Volkswagen service center immediately.
In a sealed cooling system, the coolant level can drop when the engine overheats, causing the coolant to boil and be blown out.
Topping up the coolant
Stop the engine and let it cool down. Cover the expansion tank cap with a rag and carefully unscrew it counterclockwise.
If under the circumstances you do not have G12 A8D low-temperature concentrate, do not add another concentrate to the system. In this case, you can add water and, at the first opportunity, be sure to restore the required composition of the coolant by adding the recommended low-temperature concentrate.
If there is a large loss of coolant, topping up should only be done on a cooled engine to avoid damage.
Do not fill the coolant above the MAX mark: excess liquid will expand and flow out of the cooling system through the safety valve located in the cap.
Tighten the expansion tank cap securely.
This article was copied from the website audimanual