If you mean engine coolant is getting into the car, the heater core is leaking coolant causing the coolant level to drop and that causes the engine to over heat.
your car is broken
Check the thermostat, it may be stuck in place.
check your coolant levels & if car overheating, might well be the cylinder head gasket is away.
It's steam from boiling coolant (or water) coming out of the overflow hose connected to the top of the radiator just below the level of the cap.
Is your fan coming on?
It could just be that the water pump is not properly working. Have you checked all the could-be causes for your car overheating if not then do so.
Your oil is probably leaking. If the car is old, then it's likely to be scrap!
Your car is overheating when idle because there may be a lack of oil or water in the engine. It can also be a problem with the engine itself. If your car is overheating, simply contact a wrecker or a road assistance company. The police are also available to assist you.
Maybe the belt for the water pump is loose
Either the water pump impeller is loose on it's shaft, or you have a leaking head gasket.
If your Ford Aerostar is overheating and losing water, it may be a bad radiator. You need to take your car in to get serviced.
probably a bad water pump................