You can warp the head and crack the block if you keep it running for too long while its overheating, that's only two things. Fix the problem before you blow the engine.
my car isn't steaming only in drive but not overheating.
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.
You should not buy a car with overheating problems. This means that it will not serve the purpose and will develop other mechanical problems.
your car is broken
It means the car is overheating.
There are several reasons why your car may be overheating. Check the thermostat to be sure it isn't stuck. If the car revs up and down, the timing may need to be adjusted.
Genrally depends on Trasmission of what? Generally answer can be overheating or undercooling
Either the water pump impeller is loose on it's shaft, or you have a leaking head gasket.
To prevent the engine from overheating.
Yes
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.
If the engine is not overheating and the temp gauge reads normal, the thermostat is doing its job. If the engine is overheating, the thermostat may be stuck and in need of replacement.