Need to know what to hot is. A typical cooling system will run at 200 degrees F (+ or - 5 degrees). This is normal.
possible hole in hose
There are plenty of ways a car can break down without the radiator being a part of the cause. As for the reason you'd see steam from a radiator, it would escape if there was a leak in the radiator or the hoses, or if the cap was opened. The contents in a radiator are very hot - hot enough to produce steam.
my ml500 does not give enough heat inside
Do it when the car is cold if the radiator is hot fluid may be forced out when you take off the cap.
Many things can go wrong with a car radiator. Since the car radiators job is to keep the car from over heating, the radiator can become to hot and become damaged, and it can also become clogged with dirt and debris. A car radiator can also become rusted and sludge can get built up in the wires which will cause it to over heat.
When a car is hot, keep the car running and add water to the radiator. When a car is cold, you can simply put the water into the radiator.
timing is wrong, coolant leak, bad radiator or thermostat, head gasket....
the hoses leading to and from your radiator might be clogged. If you had a rusty radiator, the rust may have clogged the hoses that carry the coolant. you should check all your hoses and even flush them out.
Hot water in the radiator is under pressure and can burn you.
Water pump. Could be going out or just belt slipping. Also a sticking thermostat.
The heater core is a radiator in the car, warmed with coolant from the engine. When you put the Air-con on hot, and turn the fan on, the air is blown over it to warm the air (and you in the car) up. As it contains radiator fluid, it can cause the level to drop if it leaks. Check the carpets in the car to see if they are wet with radiator fluid, or to see if the car leaves a puddle of fluid coming out of the air con condensation drain.
In a radiator, the fluids get really hot, when things get hot they expand and then they have to go somewhere, the fluid goes into an overflow.