07 Tacoma Sloshing noise + No heat

2007 4.0L V6
Hi all. Every so often when I drive I hear a sloshing noise comming from my dash, I checked my coolant and it was good. So I just left it alone and kept driving. Now I am not getting any heat in my truck, spits out a tiny bit of hot air then stops. I’m reading that burping the coolant system may help with the sloshing, but now I’m lost with this heat situation. Is the heater core possibly broken? If I were to just burp the coolant system would it likely fix both problems?

don’t have much knowledge with vehicles, am slowly trying to learn as much as I can so sorry if it doesn’t make much sense.

 

Are you checking the coolant by opening the cap on the radiator?
Or just by looking at the reservoir?

 

I originally was just looking at the reservoir to check for coolant level. When I went to open the radiator cap it was completely empty. I was told from my mechanic that everything was topped off so I’m not sure why it could be empty, leak in the line maybe?. Tomorrow I will fill the radiator and make sure there is no leaks, and also see if it fixes the no heat issue, thanks

 

Heater core is a high point in the cooling system. If the level gets low it loses its supply of hot coolant. You can hear the airpocket sloshing around and the heater performance drops. Top it off at the radiator and keep an eye on it

 

Coolant being low after recently being topped off plus the sloshing noise meaning air or other gases in the system and this being a 2007 are kind of all red flags for head gasket failure here.

 

cooling system pressure test and cylinder leak down tests are in order