This is standard on most all vehicles. When the antifreeze warms up it expands. Thus the reason for the overflow. Cars have had them forever, if it spills out onto the ground you have either overfilled it or you may have major engine problems, such as a blown head gasket or various other possilbe problesm
If losing anti freeze but not visible leaking typically means bad head gasket. Antifreeze is leaking into combustion cylinder and therefore evaporating and going out exhaust pipe as steam.
you might have a blown head gasket and the coolant is leaking into the cylender and the engine is burning it.
Most of the time it is because the water pump is going out and it is leaking where the pulley is on the engine.
The overflow tank for coolant will "boil" if there is air getting in the coolant chamber. This can be a head gasket going bad.
( Yes ) you might have an internal leak to the engine Is the engine oil level going up , or look " milky " With the engine warmed up and running is there white smoke coming from the exhaust pipe
if you have antifreeze in the oil means you have a leaky head gasket.... or if your engine has the oil lines going to the rad like some s10s had get a pressure check on the rad could be leaking there as well
It could be leaking from the water pump. There is a small hole in the bottom of water pumps that will leak coolant when the bearing id going out. This is so you have an indication of failure before it comes apart and destroys other engine parts.
If there is no leak visible so you can see antifreeze under the parked car, you probably have a head gasket going bad. You may have some signs of steam in your exhaust, or at least a sweet smell coming from the exhaust. You should have a compression test done on your engine. That is exactly what the overflow reservoir is for. When the engine is hot, excess coolant goes into the overflow tank, as the engine cools,it draws coolant back into the radiator.
1) If the oil cooler is leaking, it could be going into the oil. Check inside the oil filler neck for "cream". 2) The oil cooler cover could be leaking. If coolant leaks from there, it hits the exhaust manifold and burns off before hitting the ground. 3) Best idea: Get a bottle of commercial auto leak tracer dye. Leaks stick out like neon under a UV light.
Ground water can get into most older septic tanks through gaps in the concrete.
I'm not a mechanic / technician but it sounds like your heater core is leaking Have you noticed if your engine coolant level is going down ?
The heater core has no overflow hose. Cooling system is a closed loop system and the only overflow hose is the one going from the radiator cap to the reservoir. A thermostat that is stuck closed will cause the engine to overheat. Drain and flush the radiator, replace the thermostat, install a 50/50 mix of antifreeze and distilled water, bleed air from the system. You may also need to replace the radiator cap. Be sure and replace these parts with OEM parts.The heater core has no overflow hose. Cooling system is a closed loop system and the only overflow hose is the one going from the radiator cap to the reservoir. A thermostat that is stuck closed will cause the engine to overheat. Drain and flush the radiator, replace the thermostat, install a 50/50 mix of antifreeze and distilled water, bleed air from the system. You may also need to replace the radiator cap. Be sure and replace these parts with OEM parts.