I have a hot coolant small in my Yukon (aka Tahoe) inside the truck and outside when standing near it. The smell inside isn't bad until I turn on the heater, then it gets way worse.

I'm assuming the problem is the lower intake manifold gaskets leaking coolant onto the hot engine, which then enters the inside of the vehicle through the heater, but I'm wondering if it's something simpler, as sometimes there is a gurgling and sloshing sound inside the cab.

Not sure if it's important to note that my AC worked when I bought it a few months ago but doesn't work now. The blower motor is fine though.

Any ideas what to check? I don't want to rip my entire engine apart and buy an expensive gasket if it's the heater core or something else.

Thank you for any help!

 

Maybe start with a pressure check on the coolant system. Sloshing suggests low coolant level to me. Also, I wouldn't expect to smell coolant outside vehicle if it's the heater core.