make sure it isnt EATING coolant.
white smoke = blown coolant seals
it could be a few reasons
1. radiator is cracked
2. upper and lower radiator hoses are cracked
3. other coolant lines are cracked
4. broken overflow tank
5. broken radiator cap
6. water pump
7.water pump gakestS
what i say you do is fill up radiator with distilled water or 50/50 coolant then put the cap on the radiator and sqeeze thet upper radiator hose(just cause its easy to get to) listen for squirting.
if i were you since it is an 1986 you shoudl replace all the coolant lines no mater what. also beware of the fuel pulsation dampaner (sp). they are known to crack and spew fuel all over and light your car on fire :o :o :o :o