You need to double check that coolant, white smoke is a sure sign of a blown head gasket, especially when added to an overheating issue.
Could be low on coolant.
how to add coolant to 1991 lumina?
Check that there is enough engine coolant. Check to insure that the thermostat is not stuck, and that the water pump is circulating. Turn on the heater on high and high fan. If the temp drops even for a bit this is an indication that the coolant isn't circulating properly and the thermostat or pump are bad.
coolant sensor replacement need it
green
Upper intake manifold plenum leak/crack most likely. If its blowing out coolant then you probably have a bad head gasket.
Dexcool by GM.
12.5 quarts
Read the owners manule.
Engine? 3.1L V6 are notorious for intake manifold gasket leaks. get it fixed soon or your engine is at risk. My Lumina had oil in coolant and coolant in oil. If there is tan foamy stuff on oil fill cap, coolant is in oil too.
unfortunately, that usually means a head gasket problem. there are channels throughout the block and head that allow coolant to flow through and cool the engine. where the head and block mate, the only thing between these passages and your cylinders and therefore oil, is you head gasket. my 95 lumina blew it's head gasket, which dumped the coolant into the oil. I had checked the oil that morning, and it was good to go. when my engine started overheating, the first thing i checked was the oil, and it was full of coolant. sorry to be the bearer of bad news.
add to coolant recovery tank!!!