a gasket as a rule
It's probably a head gasket problem.
When it was damaged. If you don't have coolant leakage, but the level collant drops down it means you have internal leakage of coolant. You must replace the head gasket of course if want to drive your car. van over heats
You will notice the coolant reservoir level low with no signs of leakage, as the condition advances you may notice white, sweet smelling exhaust coming out the tail pipe and worse, engine coolant mixing with the engine oil.
1) Your engine is overheating and the coolant is boiling. Or 2) Exhaust is leaking into the coolant, probably through a bad head gasket or cracked head.
A blown head gasket is about the only way to get water into the oil, it should be coolant though. If you are running only water in your radiator you have probably been experiencing some leakage or overheating issues and replaced the coolant with water as an emergency measure. ( plain water will do damage to your aluminum engine parts )
Sounds like a head gasket issue, or worse, your head could be cracked. Check your exhaust - that's probably where your coolant is going.
It sounds like a jalopy, or it sounds fine. But, you will probably lose coolant throughout the engine and the coolant will mix with the engine oil. Your low coolant light will probably come on a few times a week.
If this happens only when engine is cold it is a normal condition If this hasppens when engine is at normal operating temperature it may be a sign of head gasket leakage Check to see if oil is getting into coolant or coolant getting mixed with engine oil
You probably have a bad head gasket on your engine.
The head gasket sits between the head and the engine block if it is leaking out where you can see the coolant, yes you can smell the coolant if it is leaking into the engine no you cannot smell the coolant. You can check the oil to see if it has coolant in the oil if it does then the head gasket might be blown.
If there really is no leak then it is likely a head gasket allowing coolant to leak into the cylinder and go out the exhaust as steam.