If it's the RADIATOR that's steaming it probably means that you have a leaky radiator. If the cap is steaming it might just mean that you need to replace the radiator cap, but it could mean that the engine is overheating. Check the coolant level and make certain that you do not see evidence of leakage anywhere around the engine or radiator. After the engine has cooled, look for light green powder around the edges of the radiator and around the water pump. This is evidence of leakage.
maybe my radiator is defective
There are 2 fans that would be running while you are driving and that is normal... the compressor fan if you have the air conditioner running and the radiator fan runs to help keep the radiator cool while the engine is on.
It is probley just the engine coolant burning that ran into the exhaust and muffler. Just let it run awhile and burn it out. If it don't stop steaming after about 30 mins. Then you have done something wrong when putting it back together. Are you changed the wrong head. Start the engine with the radiator cap left off and keep watching in the rad while the engine is running, there should be no bubbling coming from the radiator. If there is then you still have a bad head are head gasket. Radiator should build NO pressure in it while the engine is running.
over heat
directly in the radiator while the van is running
first turn on the car and add the water to the radiator while the engine is running-- this allows the water pump to work and force the water to all the thirsty parts this will help the radiator and the crankcase fill much faster
If the water is circulating, simply fill the radiator while the car is running. If there is an air blockage, a heate hose that loops up, you can install a T fitting in it that will allow the air to escape. Usually running the car while filling will do it.
Drain radiator, rinse with water or radiator cleaner, then refill. Don't forget to check the leve after running the engine a while.
It is best to do it while your vehicle is running so it will circulate through the system. You should add it to the reserve tank, never open the cap on your radiator (if it has one) while the system is hot.
If the question is: why does your top radiator hose get soft while the engine is running? If that's what u want to know, it's because the thermostat in the engine opens to flow the coolant thru the motor to keep the operating temperature from getting to hot. It's stores water in the radiator which cools the water and the thermostat blocks it until a predetermined temp.
A hole in the radiator would do that, or a damaged radiator cap. It could be a cracked engine block that is allowing cylinder pressure into the cooling system, pressurizing the water until it breaks through a weak spot in the radiator.
you have a leak in a hose or your radiator itself. Look for antifreeze dripping from under car while engine is running and hot enough for the fan to kick on.