Im looking into this problem for a friend but I went with him to look at a 86 honda hatch and it has a few problems. The car starts up fine no smoke or anything idles fine. But after it gets warmed up a little bit it has heavy white smoke come out of the back and the idle gets weak till the engine eventually dies.

 

Could be the headgasket. white smoke usually signifies coolant/water being burned. #1 check your coolant level and top it off if its low. #2, take the radiator cap off and start the car and let it run for a bit. Look for bubbles in there and smell for an exhaust smell coming out of the radiator. This is an easy indicator of a blown headgasket.

 

head gasket, or i dunno on these cars but i've seen some that collant passes through the intake manifold.