Heater blows very hot, coolant level dropping slowly.

[maralieus]

I replaced the thermostat and refilled the system completely on my 2007 Yaris. It wasn't blowing heat at all before, but now it's blowing heat that after driving for ten minutes or so, becomes so hot you can't even put your hands in front of it. I think it's the water pump because it makes a low growling noise coming from that area, but it's only intermittent, and it stops if I turn the interior fans off, so maybe it is actually the fans? It's really hard to tell exactly where the noise is coming from. I don't have the money to replace every single part rn, I need to get it right. Any help would be appreciated so much. Thanks for reading!

[WeeYari]

I'm thinking you have an air lock in the cooling system. That would explain the very hot air and levels dropping. Remove the rad cap and run the car for a few minutes to burp out any air which may be trapped. Top of the system, replace the cap and see if anything changes.

[maralieus]

I'll give it a try