Do you hear buzzing, clicking, humming, grinding, roaring noises inside the transmission or a burning smell when driving your car? Does it behave unusually on the road?
The most important thing is to take the car to a specialised mechanic to diagnose the cause of the problem correctly.
The car’s transmission system is a key component of any vehicle, responsible for controlling the power generated by the engine and transmitting it to the wheels to move the car. It plays a key role in determining vehicle speed, efficiency and performance. The transmission allows a person to apply power to a vehicle in a controlled manner, without which the car would not move efficiently. The components of a typical car transmission system refer to the whole drivetrain, including the:
Gearbox: The gearbox is the central component of the transmission system. It contains a number of gears and is responsible for varying the speed and torque of the engine’s power as it passes to the wheels. There are two main types of gearboxes:
- Manual transmission: In a manual transmission, the driver manually selects and engages gears using a shifter and clutch pedal. This type of transmission offers greater control but requires driver intervention
- Automatic transmission: On the other hand, an automatic transmission automatically shifts gears without the driver’s manual intervention. It uses a hydraulic torque converter to manage gear changes.
Clutch (manual transmission): In manual transmission vehicles, the clutch is a critical component that connects and disconnects the engine from the transmission. When the driver presses the clutch pedal, it disengages the engine from the transmission, allowing gear changes.
Torque converter (automatic transmission): replaces the clutch and transmits power from the engine to the transmission.
Gears: are sets of interconnected toothed wheels inside the gearbox. They have different sizes and regulate the speed and torque of the power transmitted from the engine to the wheels. Lower gears provide more power but less speed, while higher gears provide more speed but less power.
The drive shaft: also known as the propeller shaft, transmits power to the vehicle’s differential. It connects the transmission output shaft to the differential input shaft, which transfers power to the wheels.
Differential: The differential is located in the axle housing, allowing the wheels to rotate at different speeds when the vehicle turns. This ensures that the inner and outer wheels cover different distances during a turn, improving stability and control.
Axles: Axles are shafts that connect the differential to the wheels. They transfer power from the differential to the individual wheels, allowing them to rotate and drive the vehicle.
Transmission Fluid: Transmission fluid is essential for cooling and lubricating the transmission components. It helps maintain smooth gear changes and prevents overheating.
Shift Lever (Automatic Transmission): In vehicles with automatic transmissions, the shift lever allows the driver to select between different driving modes, such as Park (P), Reverse (R), Neutral (N), and Drive (D).
Control Module: Many modern vehicles are equipped with electronic control modules that manage the operation of the transmission. These modules monitor various factors, such as vehicle speed, engine load, and throttle input, to determine the optimal gear selection for fuel efficiency and performance.
Transmission failure warning signs
As with any car component, detecting transmission problems in time can save a lot of money and prevent further and more severe damage to the vehicle. That is why it is essential to learn how to recognise the warning signs of a transmission problem and what to do when you start to see signs of transmission failure.
Check engine warning light on the dash: If the sensors identify problems with the transmission system, the engine warning light appears on the dashboard. (The engine warning light can also appear on the dashboard when there are other problems, but it is always better to pay attention to it and immediately take the car to a specialised mechanic for an accurate diagnosis!)
Slipping Gears: An important indication of a deteriorated transmission is gear slippage. This occurs when the transmission struggles to engage a gear properly or shifts from one gear to another while in motion. You may observe that your vehicle has difficulty accelerating and the engine revving up more than usual without a corresponding increase in speed. Various problems, such as an insufficient transmission fluid level or damaged gears, can be responsible for this slipping phenomenon. If neglected, this symptom can escalate into more severe transmission complications, including total failure or damage to other vital components. This becomes particularly dangerous when driving on motorways or in heavy traffic, as the sudden loss of power or control poses the risk of a collision. It is imperative to have the transmission inspected as soon as gear slippage is noticed to avoid further damage and ensure safety on the road.
Hesitation or refusal to shift gears: If your car hesitates or flat-out refuses to shift into the right gear, it’s a clear sign that something’s up with the transmission. The issue can be electrical, hydraulic, or mechanical. Sometimes, it feels like a delay when shifting from drive to park before the gear kicks in, especially in cars with automatic transmissions. For those with manual transmissions, the problem often appears as a mismatch between the engine revving up and the vehicle’s actual speed. In simple terms, the car should accelerate more based on the engine noise, but it’s not. People often refer to this as the transmission “slipping.”
Burning smell: The burning smell in a car is never a good thing. If you smell burning but do not notice oil leaks, the transmission fluid will likely be overheated. This can occur due to clutch debris, broken metal parts or sludge build-up. The problem is common in vehicles that have exceeded 100,000 kilometres in which the transmission fluid has never been flushed or changed.
Are you wondering how to identify the smell of burnt transmission fluid? When automatic transmission fluid (ATF) burns, it emits a distinct, unpleasant odour, more akin to burnt rubber than burnt oil. If it overheats, you may also see smoke. Once burnt, the fluid can no longer do its job properly: handle heat, lubricate parts and shift gears smoothly.
Car in limp or emergency mode: Modern vehicles have a safeguard mechanism to reduce the chances of transmission failure called limp or emergency mode. When the vehicle’s computer system identifies an issue, it shifts into limp mode. In limp mode, the car operates in a single gear, usually the third gear, preventing a complete transmission failure. This implies that you won’t be able to drive your vehicle in any other gear during this mode.
Unusual Noises: Strange noises, such as whining, clunking, or grinding, while the vehicle is in gear. Various issues, such as worn gears or bearings, low fluid levels, or damaged synchronisers, can cause these noises.
Strange noises in neutral: If the car’s manual transmission makes weird noises when leaving the clutch in neutral, the transmission should be inspected by a certified mechanic.
Transmission Fluid Leaks: Puddles or spots of red or brown transmission fluid under the vehicle. The fluid in a transmission is responsible for cooling, cleaning, and lubricating the transmission’s internal components, including its gears and clutches.
Transmission warning light on the dash: indicates a faulty transmission, gearbox issues, or a low fluid level. When the transmission warning light comes on, the best thing to do is to stop driving, especially if you experience gear-shifting problems or low fluid levels. Immediately take the car to a workshop for a complete check to avoid permanent damage to the transmission.
Always remember that by paying attention to your vehicle, you can quickly identify potential problems and intervene as soon as possible to avoid more significant damage. Here are some tips that will help you prevent damage to your car’s transmission:
- Check for fluid leaks regularly;
- Ensure that your vehicle is serviced regularly;
- Don’t ignore the check engine or transmission warning lights;
- Listen for strange noises;
- Take your car to a repair shop if you notice any strange smells.