Thermostat stuck?

[MoparDan]

Sitting in traffic in The Cherry Bomb, roommate sees smoke coming out the passenger side of hood, pop the hood anti freeze is pouring out the overflow bottle (temperature gauge doesn't work so no help there) luckily we're right across the street so we let her cool down 10-20 minutes and drive home with the heater blowing high, I can also see some seepage around the thermostat housing, so I'm guessing the thermostat is stuck closed, does this sound right?

 

[AMC Diplomat]

I've been chasing leaks in my coolant system the whole time I've owned the car. I fix one, and it leaks somewhere else. You probably have to change the water neck gasket, might as well change the thermostat while you're doing it. Mine has leaked 3 times. The Fel Pro gasket lasted almost a whole year, so I'd recommend that one. It's the same gasket that is used on Chevys.

Those '78 and up water necks are stupid. On my engine build I'm using an intake off a '70 340 and I'll be glad to be rid of that stupid leaky water neck.

 

[MoparDan]

I always change that housing gasket when I change the thermostat, the one I got from Napa hasn't leaked at all since I changed it 4-5(?) years ago, maybe I got lucky? I think mine was changed at some point, notice the big bolts, those were there when I bought her (you can see the seepage and the remains of Mopar blue paint that didn't hold)

 

[AMC Diplomat]

I've got the stamped water neck on mine. Yours looks like a cast one.

You can try filling the system with water and then watch to see if it leaks out anywhere. Beats changing the thermostat

 

[MoparDan]

Well thermostat in, and no leaks or anything, so it was the thermostat