Your radiator might have a small pinhole in it, causing it to not build up pressure.
Waterpump, thermostat, radiator, radiator hoses.
check or replace thermostat
Dirty or plugged radiator Water pump Defective radiator cap Thermostat Cooling fan not operating hoses collapsing
check thermostat, first, then look for radiator leaks, hoses that might be leaking.
First, I would change the thermostat, easy on these models. Then check it from there. It could also be the water pump, not circulating enough. Could also be a blockage in the hoses or the rad. But, go with the thermostat first.
Yes or possibly a stuck thermostat. this is most likely a stuck thermostat. Heater uses water coming through hoses to heat the air. If the thermostat is stuck, the water in the hoses does not get hot. it also explains why you're overheating. be sure to top off coolant after you fix the problem.
Check the coolant level, the cooling system hoses and the radiator, if it's fine you need to check the thermostat.
Probably the thermostat is sticking.
Purg The Air Out of the Cooling system
your engine is overheating, change your thermostat first, if that doesn't fix the problem check the rest of your coolant system (hoses, lines, core, radiator,ext.)
Did you put the thermostat in backwards? I would check to see where the steam is coming from. I had to change out small hoses for the same problem with mine.
Overheating in a Geo Metro can stem from several issues, including a malfunctioning thermostat, a leaking radiator, or a failing water pump. Additionally, low coolant levels or a clogged radiator can impede proper cooling. Regular maintenance, such as checking coolant levels and inspecting hoses for leaks, is crucial to prevent overheating. If the problem persists, it's advisable to consult a mechanic for a thorough diagnosis.