When the low coolant warning light comes on and the car has enough coolant, it usually means there is a problem with the coolant level sensor system. The sensor may need to be replaced.
The radiator cap could be the cause of coolant reservoir overflow or backup. Have the cap checked to see if it is bad.
It sounds like the tank has a leak.
Defective radiator caps or tubes
I had this problem ....Head Gasket or radiator cap
There are a couple of things that can cause oil to get into your coolant reservoir. A blown head gasket or a broken piston ring are the most common causes.
if there is oil in the coolant system it could be a crack in the intake, a ruined intake gasket, a cracked cylinder head
Sometimes the reservoir tank is broken, where the water pump is located. Im sorry, I was confussed with the winshield tank. But, the coolant reservoir tank sometimes leak in small holes in the base or near the cap.
Need to check to make sure your coolant level is ok. Do you have a gauge? Is it running hot? Ans: The level sensor in these cars is sensitive. Typically adding a few ounces of coolant to the reservoir until the level is just above the upper hose will solve the issue. If you still have a coolant light, the sensor has failed. It is easy to replace.
the reason why the coolant is spilling up over the reservoir is because the thermostat needs to be replaced because when the engine needs water the thermostat heats up from the engine and causes the springs to expant which opens a seal to allow the water throughout the engine i just realpaced the thermostat in my volkswagen
Low coolant level which causes an air pocket in the engine.
Probably the level of brake fluid in the reservoir is low. This is telling you the brakes need service.
Mercury.