The automatic transmission requires careful handling and timely maintenance, otherwise it may fail due to overheating. This problem can lead to costly repairs or replacement of the transmission.
At what temperature should the automatic transmission operate?
The temperature of the automatic transmission depends on the type and model of the transmission and the vehicle’s operating conditions. On average, the normal operating temperature of the automatic transmission is between 50 and 90 degrees Celsius. If the temperature rises above 100 degrees, it is considered to be overheating. At the same time, the maximum permissible temperature for the automatic transmission is 130 degrees Celsius. If this temperature is exceeded, irreversible destruction of the gearbox will begin.
The temperature of the automatic transmission can be monitored by means of a sensor installed on the body or in the oil sump. The sensor indicates the temperature of the oil in the automatic transmission, which lubricates, cools and transfers pressure inside the gearbox. Some cars also have a temperature gauge on the dashboard to indicate overheating.
What happens if the automatic gearbox overheats?
An overheating automatic gearbox is a dangerous condition that can have serious consequences for the gearbox and the car as a whole. Firstly, overheating of the oil in the automatic transmission causes it to oxidise and its properties to deteriorate. The oil loses its viscosity, lubricating and cooling properties and begins to form deposits in the form of tar and coke. This, in turn, causes wear and damage to friction, gears, solenoids, valves and other parts of the gearbox.
Secondly, overheating of the automatic transmission can cause the oil tubes connecting the automatic transmission to the radiator to leak or rupture. This problem leads to loss of oil and pressure in the box, as well as antifreeze entering the automatic transmission. As a result, the box can fail completely or even explode.
Thirdly, overheating of the automatic transmission can affect the operation of the engine and other car systems. An overheated transmission transfers some of its heat through the oil pipes and radiator to the engine, raising its temperature. This causes the engine to overheat, reducing its performance and resources and increasing fuel consumption. Overheating of the automatic transmission can also cause malfunctions in the vehicle’s electronics.
How does an automatic transmission behave when it overheats?
Overheating of the automatic transmission does not go unnoticed by the car and the driver. It is therefore important to know how the automatic transmission behaves when it overheats. It is characterised by
- RPM jumps. When overheating occurs, the oil loses its viscosity and can no longer transmit the torque from the engine to the wheels normally. As a result, the engine speed starts to change abruptly when changing gear. This may be accompanied by jerking, shuddering or delayed shifting.
- Loud noise. Overheating causes wear and damage to parts that start to make unpleasant noises when driving. This can include whistling, squealing, humming, knocking, crackling, etc. The noises can be heard from both inside and outside the car.
- Change in colour and smell of the oil. Overheating of the oil causes it to oxidise and form deposits. The colour of the oil may turn brown, black or even red (if antifreeze has been added). The smell can become burnt, pungent or sweet.
How to detect automatic transmission overheating: key signs
Automatic transmission overheating is a serious problem that must be detected and remedied in time. To do this, you need to know the main signs of automatic transmission overheating. To do this, you need to keep an eye out:
- Automatic transmission temperature gauge. Some cars have a special indicator on the dashboard. It signals overheating by showing a red or yellow symbol in the shape of a thermometer or the letter A with a thermometer. If the indicator lights up, it means that the gearbox temperature has exceeded the norm.
- Temperature sensor. If the car does not have a temperature gauge, you can install an additional sensor. This shows the temperature of the oil in the automatic gearbox on a separate screen or on a smartphone via an application. Such a sensor will help control the temperature of the automatic transmission and prevent overheating.
- The condition of the radiator. This element of the cooling system removes excess heat from the box. To check the condition of the radiator, you must open the bonnet and inspect it for damage, dirt, leaks or corrosion.
- The condition of the oil lines. These elements of the cooling system connect the engine compartment to the radiator. To check their condition, you should inspect the pipes for damage, leaks, blockages or kinks.
Causes of automatic transmission overheating
Having considered the signs of automatic transmission overheating, it is worth talking about the causes of such a situation:
- Low oil level. Oil lubricates, cools and transmits pressure inside the gearbox. If the oil level is too low, it will cause overheating, wear and damage to the parts of the automatic transmission. It is therefore important to check the oil level regularly and top up if necessary.
- Poor quality oil. The oil in the automatic transmission should meet the specifications and recommendations of the car and gearbox manufacturer. If the oil is not suitable in terms of viscosity, composition or quality, overheating, oxidation and deposits in the gearbox will occur.
- Clogging of the cooling system. Another cause of automatic transmission overheating is clogging or damage to cooling system components.
- Agressive driving. This includes frequent acceleration, braking, gear changes or driving at high speeds. Such a driving style will lead to increased stress on the automatic transmission and overheating.
- Unfavourable weather conditions. Looking at the causes of automatic transmission overheating, it is worth noting that heat, strong winds, mountains or traffic jams can also cause the problem. It is therefore important to monitor the weather and adapt your driving style accordingly, as well as to use additional means of cooling: air conditioning or another radiator.