It is possible for radiator fan to spin in a wrong direction due to placement or connection. This can cause engine overheating and also waste energy. It is sometimes difficult to track this fault since the fan still rotates.
Radiator fan speed is normally controlled by the ECU or fan control module. If the system is bypassed, it has negative side effects like high fuel consumption, shortened fan lifespan.
There are different ways of bleeding different cooling systems. Some methods are not very easy and straightforward and requires some level of expertise. This quick method can be used by an average car user.
Coolant can gain access to transmission through the transmission oil cooler. The oil cooler can leak internally causing the coolant and oil chambers to be linked.
Coolant getting into the engine lubrication system can cause damage to the engine. It is mostly caused by a faulty head gasket, bad radiator that has oil cooler integrated in it or a bad engine oil cooler.
Just as engines overheat, it is very possible for them to also be overcooled by their cooling systems or overcooled by the inrush of environmental air passing through the radiator.
There are salient causes of overheating that are hard to troubleshoot. One symptom is coolant bubbling even before engine attains operating temperature.