- hydrometer for measuring the coolant concentration or the HAZET 4810-B measuring device for checking the electrolyte density and coolant concentration. The corresponding hydrometer can be used at a filling station.
Materials required:
- antifreeze,
- distilled water.
4. Warm up the engine until the upper radiator hose is slightly warm. The coolant temperature in the expansion tank should be approximately +20°C.
5. Carefully unscrew the expansion tank cap.
Caution! Do not remove the tank cap when the engine is hot, see also "Coolant - Checking the Level".
6. Use a hydrometer to take the coolant from the expansion tank and use the hydrometer scale to determine its density (see illustration). In our climate conditions, the coolant should not freeze at air temperatures down to -37°C, which is ensured by a 50% ratio of antifreeze and water.
7. Increase the percentage of antifreeze in the coolant using the table below if necessary.
Increasing the density of the coolant
Example: When measuring the density of the coolant in a car with a gasoline engine, it was found that the coolant added provides protection against freezing only at an ambient temperature of -10°C.
To ensure freeze protection at temperatures down to -37°C, 2.1 litres of coolant should be drained from the system and 2.1 litres of clean antifreeze should be added to the system.
Attention! The calculations in the table above are valid at a coolant temperature of +20°C.
Warning! Do not mix coolants of different brands and colors. This may cause significant engine damage. If the system is accidentally filled with coolant that does not meet the vehicle manufacturer's requirements, drain it immediately and flush the system with clean water.
8. Close the expansion tank cap and check the coolant level after a test drive.
Attention! If the concentration of antifreeze in the coolant is too high, its cooling effect decreases and the freezing threshold of the coolant in the system decreases. This is observed at a percentage of antifreeze in the coolant starting from approximately 55% and higher.