Temp spike then smoke coming out vents then all normal?

[Kmenex]

Greetings,

 

Anyone out there maybe help me figure out what's going on?

 

Just replaced left and right head gasket and timing belt and water pump. After putting engine back in I added oil and coolant by slowly filling radiator with air bleed line open… then I started car, ran very smoothly, let it idle for 30 minuets. Ran very well, got to temp, very steady rpm, no hiccups… let it rest twenty 20 min then checked coolant and oil and added more. Next I took it for a test drive, 30 miles… ran perfect, like a new car. I was having power issues prior to repair now no power issues.. strong runner.

 

Let it sit over night then started it up this morning… ran fine but 10 minuets in I noticed the temp gauge was sky rocketing… pulled over instantly let it idle. I noticed smoke was entering the cabin, maybe coolant vapor. Turned on the fan and smoke poured out… then the fans kicked on and I'm guessing the thermostat opened up and it went right back down to temp and stayed steady both while in gear and coasting.. no more smoke coming into cabin…

 

Can anyone help me understand what's going on? I dont think it's the head gasket leaking as there was no power disruption at all and when was neutral coasting down hill no temp changes. Maybe a leaky hose? Heater core clog? I'm open to suggestions.