In many cases, the transmission system will make strange noises when it experiences damage or extreme wear and tear. The following are some of the specific causes of auto transmission noises.

Low or Stale ATF

One of the major functions of the auto transmission fluid (ATF) is to lubricate various parts of the transmission system. Since most parts of the transmission system are mostly metal, lack of lubrication is dangerous because it accelerates wear and tear and also impairs movements of mechanical parts.

If the ATF leaks and its volume reduces, it won't provide the necessary lubrication. As a result, metal-on-metal friction will increase, making noise each time the car is in motion. The same thing is possible if the ATF is stale and dirty and its lubricating properties are compromised.

Gear Damage

Physical damage to any of the gear sets can also generate noise. If the gear is cracked or bent out of shape, say after a collision, it won't fit snugly into its opposite number, thereby generating noise. In such cases, the noise may subside when you put the car into different gear (thereby releasing the damaged gear).

Clogged ATF Filter

Since dirty ATF can damage the transmission system, the system is fitted with a filter that traps contaminants before they can enter the transmission system. The problem comes when the ATF filter also gets dirty (as it will inevitably get after some time) and further ATF cannot flow through. For one, the transmission will behave as if it is low on fluid. Secondly, the ATF will also make whistling sounds when it gets forced through the restricted filter.

Torque Converter Malfunction

The torque converter transfers power from the engine to the wheels. The torque converter is a complex part of the transmission with multiple parts any of which may get damaged. For example, the torque converter has needle bearings that get worn out with time. If that happens, the torque converter will make grinding noises due to the damaged bearings.

Damaged Transmission Mounts

Lastly, your transmission system may also be noisy due to damaged transmission mounts. The transmission mounts secure the transmission to the body of the car and also absorbs the inherent vibrations of the transmission system. With the mounts damaged, the transmission can bounce as the car moves, and the vibrations will be felt all over the car.

As you can see, there are various potential causes of auto transmission noises. Unusual transmission noises mean something is wrong with your car, and you should get a professional diagnosis and auto repair.