- Regardless of whether the engine is cold or warm, the coolant level should not be below the mark «MINI» on the wall of the expansion tank.
- Keep in mind that coolant expands as it heats up and therefore the coolant level on a hot engine will be slightly higher than on a cold one. Possible expansion of the coolant must not exceed the mark «MAXI» on a warm engine.
- On a cold engine, the coolant level in the expansion tank must be between the marks «MINI» and «MAXI».
- If you need to open the expansion tank cap on a hot engine, then unscrew it slowly, covering the top with a thick rag.
- This will relieve excessive pressure from the cooling system and avoid the seething of the coolant and its leakage. In addition, the coolant released from excess pressure begins to boil.
- When excess pressure is released, unscrew the expansion tank cap and remove it.
The coolant level must be between the marks «MINI» and «MAXI» on the expansion tank. Too high or too low coolant level indicates a malfunction, the cause of which must be determined. On a hot engine, always open the expansion tank cap very carefully, otherwise you may be burned by the hot coolant. When opening the lid, use a thick cloth for greater safety.
To check the density of the coolant, a hydrometer is used, which, depending on the version, has an arrow or, as shown in the figure, a moving rod. The rod is immersed in the coolant drawn from the expansion tank, thereby indicating its density.
Adding coolant
The loss of coolant is a signal that there is a malfunction or defect in the cooling system. Coolant is not consumed and cannot evaporate from a closed cooling system. If you had to add coolant, then you should study the section «Checking the cooling system for leaks».
- If you add only water, the coolant will lose its density, which is why it will freeze even at a slight negative temperature.
- Do not overfill coolant above the maximum mark. Coolant expands as it heats up and excess coolant will be squeezed out of the system.
- Small amounts of coolant can be topped up on a cold or hot engine.
- In the event of a significant loss of coolant and a hot engine, never top up with cold coolant. The cylinder head or engine housing can crack from temperature changes.