Yesterday i did a tune up on my 1989 gtu, ran great after, drove it about 40 miles yesterday. this morning i drove it about 8 miles or so, then went to drive it again and it started smoking really bad so i went and parked it. tried to start it but it was hot and wouldn't. finally got it running again and the temp shot up into hot so i turned it off. It has coolant in it and i can't figure out why it's getting that hot that fast.

 

Check your T-Stat. It could be stuck.

 

Figure out the color of smoke, at idle with throttle. These are good details. How long did smoke for. When? The t-stat wouldn't really explain the smoke unless it already caused a problem, unless they are not even one in the same. If you can get an infrared temp gun, check temp difference between the top rad hose and the bottom. There should be a difference. Also you can check the heater, if yours works, if its not blowing very hot compared to the coolan temp your water pump could be failing. Thats how I found mine going bad. The fan clutch could be failing, the belts could be slipping. check simple things like that before you pull the t-stat out..