Cooling system (VW Passat B3)

Contents: Checking the coolant level ↓ Coolant loss ↓ Topping up the coolant ↓

The cooling system is filled with a long-term coolant at the factory, the replacement of which is not provided during operation. The coolant is a 40% aqueous solution of concentrated antifreeze G 11 V8B (ethylene glycol based antifreeze with anti-corrosion additives). This mixture not only provides the necessary protection against frost (up to -25°C), but also protects aluminum engine parts from corrosion. In addition, such a liquid composition prevents the formation of limescale deposits and has a high (compared to water) boiling point.

In order not to reduce the concentration of anti-corrosion additives, the coolant should not be diluted with water even in warm climates - the solution must contain at least 40% antifreeze.

If the climate requires stronger protection from frost, the concentration of antifreeze G 11 V8B can be increased, but not more than 60% (protection from frost up to -40°C) - with a further increase in concentration, the freezing temperature of the solution increases, and its cooling capacity deteriorates.

Cars designed for cold climates (for example, Sweden, Norway, Finland) already at the factory they are filled with antifreeze designed for temperatures down to -35°C.

To top up the coolant, only antifreeze G 11 V8B or a special additive according to the TL-VW 774 B specification can be used (pay attention to the inscription on the package), which can be purchased at a Volkswagen service station.

Other coolant additives can significantly reduce the corrosion protection of aluminum engine parts. The resulting corrosion damage can lead to coolant loss and, consequently, serious engine damage.

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Checking the coolant level

The expansion tank is located in the engine compartment, near the bulkhead (see picture).

The correct fluid level is visible only when the engine is stopped. The coolant level with a cold engine is between the MIN and MAX marks; when the engine is warm, it may be slightly higher than the MAX mark.

Coolant loss

Coolant loss primarily occurs due to leaks in the system - in this case, the cooling system must be checked immediately at a service station. Simply adding coolant is not enough.

Topping up the coolant

Stop the engine and let it cool down. Cover the expansion tank cap with a rag and carefully unscrew it.

Caution! Do not open the expansion tank cap when the engine is hot - the cooling system is under pressure!

If, in an emergency, water is used to top up the system, the previous concentration of antifreeze must be restored at the first opportunity (see above).

In case of large losses, add coolant only to a cooled engine to avoid damage from sudden temperature changes.

Do not exceed the maximum mark: when heated, the coolant expands and is forced out of the cooling system into the expansion tank through the safety valve.

Tighten the expansion tank cap tightly.