I own a 2001 Honda Accord VTi-L (the 2.3L 4 cylinder) and as of recent. The car has started heating up. The only way it doesn't heat up is if the heater is on max (in this case, car retains normal temperature in between C and H, but will definitely exceed the red line by a bit if heater turns off).

We looked at the coolant and it was empty! Even the reserve tank. No signs of leak though. When we opened the oil cap we noticed oil was overfilled (funny, when I bought the car it wasn't overfilled so no explanation for that).

When the car overheats and gauge shows its reached to the max it does lose a bit power and smoke appears to come out from the hood near the battery side close to where the headlight sits (again no explanation for that). When I switch the car off, it kinda sounds like some liquid is being swallowed through the hose into something. It's so strange!

We're currently running the car on water at the moment instead of coolant I'll buy that tomorrow when the store opens. Any idea what it could be? As I was saying. Right now the only way to drive the car with no overheating is having the heater on. Thanks in advance.