Normally a leak in the sytem, either internal or external. More details would be required to expand on the answers to be given
Defective radiator caps or tubes
A leak.
Blown head gasket or cracked head.
pressure test the coolant system you will find a blown intake or head gasket
Can be leaking intake manifold gaskets, which can sometimes be fixed by using Dexcool coolant. Can also be a head gasket.
Could be a blown head gasket, inspect spark plugs for coolant contamination plus loss of coolant and excessive pressure in radiator
your piping for the coolant system or radiator could be leaking and causing a loss of coolant making the temperature rise. Have you had it pressure tested?
excessive muscle loss
Excessive coolant in the reservoir can be caused by a few factors, such as a faulty radiator cap that fails to maintain proper pressure, leading to overflow. Additionally, a malfunctioning thermostat or a leaking head gasket may cause coolant to leak into the engine, resulting in an overfilled reservoir. Lastly, improper coolant mixture or overfilling during maintenance can also contribute to this issue. Regular checks and maintenance are essential to prevent these problems.
No. Excessive pressure will not cause the water to boil off quickley. It will cause the radiaor hose or other components to burst causing loss of coolant. A bad radiator cap can cause high or low pressure; low pressure will cause the coolant to boil at a lower temperature.
A LOCA is a loss of coolant accident. A rupture in the main coolant system resulting in a major leak of that coolant is a loss of coolant accident, or LOCA.
A faulty head gasket will cause power loss, coolant to mix with oil, and is a costly repair. Excessive heat is the primary cause for their failure.