I'm still new to the project car area so I'm still learning how to fix some problems. But recently when I was driving my 850 turbo, the window started fogging up and coolant started making at the gas pedal area, I realized it was a heater core failure so I just finished replacing it yesterday. I refilled the coolant and was about to heat cycle the car, but when I started the car, the coolant level immediately dropped down to almost none. I checked in the car and there were no leaks or anything but I think I saw a puddle under the car ( I could be wrong, it was kinda dark). but I don't know if there is a leak or if it will fill back up, any advice is appreciated

 

Fill it up again and check for leak.. look at the firewall where heater hoses go through.

 

i refilled it and it still disappered, I cant see the leak anywhere