1990 Chevy Cavalier coolant leak

I'm sorry that the repair shop charged so much and did not even fix the problem.

White exhaust smoke is a sign of coolant entering the combustion chamber. From the sound of it, it seems you have a blown head gasket or cracked head. Stop driving this vehicle until you find out. Look for coolant in the oil, air bubbles escaping from the radiator, and/or a sweet smell at the exhaust. All indications of serious problems. A compression test will verify if you indeed have a blown head gasket. They can also run dye tests to check for cracks in the head. Check gasket first, head second.

Hope this helped.