Major causes of automatic transmission overheat
Overheating is a major killer of automatic transmissions especially when the overheating is not caught on time.
The following are various common issues that cause automatic transmissions to overheat.
Fluid leak - When the automatic transmission fluid is low due to leakage, there won't be enough fluid to circulate and dissipate the heat thereby causing transmission overheat.
Low fluid - Low transmission fluid level can be as a result of fluid leakage or incorrect fill level when the transmission was filled.
Degraded fluid - A worn out transmission fluid would not be able to lubricate parts properly thereby causing overheating as the friction of the moving parts increases.
Wrong or low quality transmission fluid - A wrong fluid can cause slippage of clutches. When clutches slip, they generate a lot of heat. Low quality fluids lubricates less and are susceptible to oxidation more than quality transmission fluids. Synthetic oils are better than mineral oils.
Worn clutches and bands/brakes - when these parts have worn out, they cause slipping which generates excessive heat.
Faulty solenoid - Faulty solenoid can cause wrong application of fluid pressure that can lead to slippage of clutches followed by overheating.
Hot weather - Ambient temperature can raise the internal temperature of transmissions especially those type of transmissions that do not have a transmission cooler or heat exchanger.
Driving habit/condition - A transmission can overheat when it is subjected to severe driving condition like harsh driving, prolonged stop and go driving and driving in terrible off-road terrain.
Faulty torque converter lock-up system - Torque converter lock-up is meant to limit transmission slip at certain speeds. If the lock-up system is faulty, the transmission could overheat after a prolonged use.
Faulty cooling system - In some vehicle designs, the engine cooling system also serves to cool the transmission also. The transmission is cooled by the cooling system via the heat exchanger.
Heavy load/Towing - When there is heavy loading on the automatic transmission either by the vehicle carrying heavy weights or by towing, the transmission temperature rises.
With these points known, I believe that you can now better take care of your automatic transmission like a baby and it will not fail you easily.