Check the coolant level with the engine not running.
When the engine is cold, the coolant level should reach the minimum mark, and when the engine is warm, it should slightly exceed it.
Caution: When the engine is hot, open the tank cap carefully. You can get scalded! When opening, put a rag on the cap. If possible, open the cap at a temperature below 90°C.
First, unscrew the cap slightly to release the pressure. Then unscrew and remove the cap.
Add cold coolant only when the engine is cold to avoid engine damage.
For topping up - even in warm weather - use a mixture of antifreeze concentrate and soft water.
Note: In order to continue the trip, it is permissible, especially in summer, to add clean water. However, it should be replaced as soon as possible.
Perform a visual inspection for leaks if the coolant level is significantly below the min mark.
External inspection of coolant leak
By squeezing and bending the cooling system hoses, identify their porous areas; replace hardened hoses.
The hoses must be deeply seated on the connection nipples.
Check the tightness of the hose clamps.
Check if the seal on the expansion tank filler cap is damaged.
Warm up the engine, check if coolant is leaking in the area of the water pump.
If coolant leaks from the hole at the bottom of the pump when the engine is hot, the seal is usually faulty. In this case, the water pump should be replaced.
It is very difficult to detect leaks. Therefore, it is recommended to do this in a special workshop using a device. Here you can also check the safety valve on the cover.
(The original article is posted on the resource: AUDImanual.ru)