Signs of transmission problems and how to fix them

Signs of transmission problems and how to fix them

Car transmission systems are complex networks of moving parts that interact to transfer the right amount of engine power to the wheels with maximum efficiency. They allow the gear ratio between the engine and the drive wheels to be altered as the vehicle gets faster or slower. The car gears are essential as without them the engine revs would be uncontrollably high, leading to the unit’s destruction. These parts are constantly subjected to extreme temperatures and pressures; regular maintenance is therefore critical for keeping your car on the road. Extensive damage can not only cost you your savings but also your safety. It is important to know the symptoms of a failing transmission to prevent further damage.

Signs of transmission problems

  • ! Unresponsiveness. If there is a delayed response or none at all when you change gears, it is most likely due to a fault in the system. If you own a manual car, you may notice a significant difference between the RPM and actual speed of the car.
  • ! A burning smell. This could be an indicator that the automatic transmission fluid (ATF) is low or has gone bad and is overheating, contributing to premature engine wear and corrosion. It should be changed regularly to keep things running smoothly.
  • ! Fluid leaks. If you spot a pool of sweet-smelling red fluid or mucky brown fluid underneath your vehicle, the ATF could be leaking out. The leak will need to be fixed first and then new fluid should be added.
  • ! Strange sounds. Clunking, whining or humming sounds are classic symptoms of problems like these, especially if you hear them when shifting gears. It is advisable to get in contact with a professional mechanic as soon as possible to get a proper diagnosis.
  • ! Grinding or shaking. For example, you may notice a grinding sound coming from the gears or the vehicle may start to shake during gear changes.
  • ! A dragging clutch. This is only a symptom for manual vehicles. It indicates that the clutch disc and flywheel are not disengaging properly when the clutch pedal is pressed. It can be caused by a faulty clutch cable or mechanism.
  • ! Slipping gears. This is a serious safety hazard for all road users and it is recommended to have the issue fixed by a professional immediately. Common causes include a lack of fluid and worn bands or gear components.
  • ! The check engine light is on. This warning could have been triggered for several reasons. The problem can be identified by doing a diagnostic scan.
    Signs of transmission problems

How to check the transmission system

How to do a diagnostic scan
 How to do a diagnostic scan: 
  1. If the check engine light illuminates, it would be a good idea to scan the system and decrypt the diagnostic trouble codes (DTCs). You can do this using an OBD2 scanner. The device should help you determine operating factors such as the temperature and transmission inputs and outputs.
    How to check the transmission system
  2. First you will need to locate the data link connector, which can usually be found under the instrument panel on the driver’s side. After switching off the vehicle, plug in the scan tool using the connector.
  3. Once you have done this, turn the vehicle on and wait for the scanner to start up. You may need to turn it on using the power button. When the device is ready to use, you can click on the scan button and follow the on-screen instructions. It will bring up a number of DTCs which indicate the problems that the onboard computer has detected.
  4. Read through the diagnosis carefully. You can look up the codes in the manual or on the internet to decipher them.
 Checking the automatic transmission fluid: 
  1. You can check the fluid level using a dipstick which is similar to the one used for oil. A lot of issues can be linked back to the fluid levels and if there isn’t enough ATF, there is probably a leak. On the other hand, overfilling the reservoir can cause the fluid to foam, putting greater pressure on the components.
  2. Before checking the tank, make sure that the car is parked on a flat surface. Run the engine for a few minutes so that the fluid is warm enough. Most manufacturers will allow you to keep the engine running for this process.

    Caution: the engine components and fluids will be hot, so handle them with care.
  3. Now you can pull out the dipstick and clean it using a clean, lint-free rag. Then place it back into the reservoir and remove it again to measure the fluid level. The markings on the stick will indicate whether the ATF is low or the tank is full.
  4. You should also check the colour of the ATF. If it is bright and clean, it is still good to use. If it is black or brown, it is probably burnt and contaminated.

It is better to have manual fluid checked by a technician as it can be difficult to access and most manual vehicles don’t have a dipstick for this.

Recommended repairs and tips

Recommended repairs and tips: transmission
  • i Transmission systems can be repaired, rebuilt or completely replaced based on the extent of the damage and whatever solution is the most cost-effective. If the situation is chronic or several faults have emerged, the best option may be to pay a technician to rebuild the transmission. This is a comprehensive process that involves taking the whole system apart, inspecting, and replacing or repairing components before cleaning and reassembling them. This way, you will have a complete overview of the situation and hidden faults can be detected. However, this is not cheap as it is quite a labour-intensive process.
  • i Leaks are commonly caused by cracks in the lines, broken seals, a damaged pan gasket, or a bad torque converter. It is possible to fix leaks yourself, if you have the necessary tools, skills, and experience to do the job. The fluid will need to be drained first before you can replace the components and change the gaskets and seals.
  • i Different manufacturers will recommend different intervals, however, the general recommendation for manual vehicles is to replace the fluid every 30,000 to 60,000 miles. ATF can last up to 100,000 miles. It is also worth considering the driving conditions and the loads that the vehicle carries, as this can influence the aging process of the fluid. You should also make sure that you are using the right product, according to the manufacturer’s instructions.


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