Hyundai Verna returns the water

I have a Verna 2000 converted gas, it is not overheats, but every day the radiator is missing and Timber plays a good amount, it returns it to the reserve jar, but it does not send it to the radiator, it is not seen leaky

If it's not heating up, the radiator cap is most likely faulty.
The cap also acts as a relief valve; if the gasket isn't sealing properly, the coolant will leak into the reservoir and empty the radiator.

Be careful not to run out of coolant in the system, due to well-known problems like cylinder head failure, etc.

The reason Bari mentioned could be the cause of the coolant loss. During vehicle use, the coolant heats up, increasing the pressure. If the cap isn't in good condition, it will allow coolant to escape along with the pressure. This happened to a friend who thought he had a leak in the cylinder head. He even removed the cylinder head, thinking it was warped. When he had it calibrated, they told him it was fine. At the end of the ordeal, they concluded that the expansion tank cap was faulty and was allowing coolant to escape, increasing the temperature.

Sometimes the cooling system doesn't have enough coolant. You might have a minimum level to prevent the engine from overheating, but it's not completely full. To fully fill the cooling system, you often have to do so with the engine running, in case there's any air in the system.

However, to be absolutely sure, you can always drain the radiator through the cap at the bottom to check the actual amount of coolant in the system. Collect the coolant in a basin and use a bottle to measure the level. You can then reuse it if you wish.

Refill the reservoir to the maximum level and drive the car. Check the coolant level occasionally and see if it changes. If it remains the same, replace the cap.

If it still persists, check the hoses for small leaks. There are tiny punctures that, if the car doesn't reach sufficient temperature and pressure, prevent coolant from escaping. When they reach this point, they release a slight drip that will increase over time.

If it continues, remember that if there are no leaks, that water has to go somewhere. You should also check the oil level in case water is seeping into the oil pan. If so, the head gasket is most likely damaged internally, allowing water into the engine's lubrication system and vice versa. There could also be oil in the coolant compartment, along with a loss of engine compression. However, based on what you've said, this probably isn't the case, as this usually raises the engine temperature considerably.

Look, the truth is I don't really agree with my colleagues. If you have to fill it with water every day because it's losing a certain amount, and this water isn't dripping onto the ground or showing any visible leaks, then the water is getting into the engine. Check the oil cap to see if it's emulsified, or the dipstick, or better yet, both. If it's not emulsified, then you have to check for leaks. It's not normal for water to be missing; it should be coming from somewhere—the reservoir cap, the radiator cap, or hoses. If it's not coming from the vehicle, then it's inside the engine. Check that there isn't excessive water vapor or droplets coming from the exhaust.