Peugeot 307 1.4HDI excessive water loss

Friends, when I got home from work today, I wanted to go shopping. The moment I started my car, the engine coolant level sensor gave me a warning. The engine coolant was completely empty. I topped off the coolant and went shopping. When I got home 3 hours later, I decided to check. The coolant had dropped to the minimum level. I looked under the car. There were no leaks on the ground. The temperature was normal. There was no white smoke either. I put a new radiator on 3 months ago. The expansion tank cap is also completely dry. What is the problem? Could the thermostat, circulation pump, oil cooler, etc. be losing so much coolant?

The heater core might be leaking. Check under the floor mat by the driver's seat to see if it's wet.

My car is a 308, 2011, 1.6HDi engine. I experienced the same problem a week ago. The leak had been going on for a while, and my mechanic told me to figure out where the leak was coming from so I wouldn't have to replace any parts unnecessarily. For a while, I'd been opening the hood every evening with the engine running and watching it, and finally, I was able to pinpoint the source of the leak. It was the thermostat. It started out a little, then progressed to leaking all the antifreeze I added. I replaced the thermostat and drove about 500 km, and the problem seems to have stopped. I'm still seeing it, but I haven't noticed any leaks, thank goodness. Have the thermostat checked, sir.

[QUOTE=Karahisarli]The heater core might be leaking. Check under the floor mat by the driver's seat to see if it's wet.[/QUOTE] That's the problem. All the water got on the floor mat. Now I'm trying to dry it. Is removing the heater core problematic? Does the dashboard need to be removed? How much will it cost me to replace the radiator?

I don't know the price, but my car had to have its glove compartment removed, sir.