1 simple cause may be a damage radiator cap or simply low fluid.
Your temp gage may be malfunctioning or you may have a head gasket leak that is making excess pressure build up in the cooling system. Have the coolant temp sensor tested for accuracy. This would also prevent the cooling fan from coming on and cause the overheating condition.
It might be a bad thermostat, or something worse, such as a blown head gasket/cracked head. Either of those scenarios will cause the cooling system to pressurized beyond it's specified capacity, and the pressure will force the coolant out of the reservoir.
possibly a leak in cooling system
No. The power steering fluid has nothing to do with your cooling system. It goes from the reservoir to the pump to the steering rack and back again.
Air trapped in the cooling system, try replacing the radiator cap and be sure the reservoir is full to line, it should bleed itself out.
Yes, under normal operation. If you are adding coolant to the reservoir often, you have a leak somewhere. Have a trusted mechanic pressure test the cooling system to determine the cause.
The only possibility is a cross-connected line between the fuel lines and the cooling system, possibly in the exhaust vapor recovery system. A leak anywhere would be unlikely to enter the sealed water circulation.
If the refrigerant is not at an optimal level (either too low or too high), the system will have to work harder to produce the same amount of cooling. This results in more electricity being used to get the same amount of cooling.
Overfilling a coolant reservoir.......isn't possible since they have an overflow line.... Water is cycled back and forth as needed... with movement of water, air in the top of the reservoir is obviously necessary, since overfilling the reservoir would cause the overall cooling system to fail to do its' job!....... In otherwords, If you try to overfill the coolant reservoir tank, it shoud automatically start draining the excess water/coolant onto the ground. The other reason for the overflow is to protect from high pressure in times of high temperatures..... steam and water can both escape this way. Chris... c-tekk@hotmail.com
If the brake fluid reservoir is overfilled, the excess fluid runs through the overflow instead of over the bodywork, which would cause damage to the paint work.
A bad gasket can cause the air fuel mixture to enter the coolant stream, and cause bubbles in the overflow bottle. The gasket needs to be replaced.
Low coolant? Cooling system airbound? Low coolant? Cooling system airbound?