Why is Your Transmission Shifting Hard When Hot?

Transmission machine is a part of transmission system, which regulates the power that comes to driveshaft from engine to keep it in moderation. Compared to other components of a car, this particular unit receives the most amount of stress due to heat and friction generated by the movement of various parts. As a result, it often gets hot and shifts hard, which is a quite common problem with car driver. The following are 9 possible reasons why this problem happens:

  • 1. Leaking or Low Fluid
  • Leaking of hydraulic fluid, including seals, lubricates as well as ATF cleans, would be the most recognizable and common sign that leads to the breakdown of machine. When this level of fluid gets low in the engine, the system will stop working completely. In general, automatic transmission fluid has bright red color and smells sweet when there is no problem with a transmitter.

    However, if the fluid has a burning smell or turns dark, then you have to flush out or change it immediately. When you need to check if the fluid amount is low, drive the car for a test to warm it up. Generally, motor oil will be burned off or consumed a car, while ATF is different. If its level is low, then there is possibly a leakage somewhere. Thus, our suggestion is to fill up the fluid even when there is a leak till you solve the problem or have it done by a professional mechanic. In addition, you should examine the transmission’s case with a fill plug to keep an eye on the amount of fluid.​

  • 2. Slipping Gears
  • The transmission basically stays in a specific gear until it performs a shift, which can be manual or automatic. If the transmission moves and slips at the same time in and out of the gear or into neutral when you are driving, it would be a serious safety threat.

  • ​3. Noisy Transmission in Neutral
  • The solution to a noisy transmission when it is noisy is not expensive. In fact, you just need to put some more fluid. If it does not work, then you should get your car checked by a professional expert as it might require replacement with the reverse idler gear, worn bearings or gear teeth.

  • 4. Dragging Clutch
  • A dragging clutch often occurs when you press a clutch pedal. In this situation, it would lead to the failure of a clutch disc in disengaging the flywheel and the output would be experienced by the manual transmission. In addition, it would be impossible to adjust the gear as the clutch is still rotating with the engine. As a result, a grinding sound will appear every time you adjust the gears.

    Compared to other causes, the repairing cost for this problem is not so expensive. Generally, the reason for this problem is that the clutch pedal has too much space. The larger the distance between a clutch disc and pedal, the more difficult you can pull away the clutch disc from a flywheel.​

  • ​5. Checking Engine Light
  • On the dashboard of your car, you can find a button with "check engine light" words. When there is an unusual activity with the engine, especially with the transmission, this light will turn on to warn you of a possible issue with the sensors, which are built in different areas of the engine. If there is any problems, those sensors can sense the smallest jerks or vibrations and then create an alert.

  • ​6. Burning Smell
  • A burning smell often happens when the transmission fluid gets overheated. As we all know, the main purpose of fluid is to keep the parts lubricated and cooled so that they do not get damaged. If its level is low, the system will turn hot, leading to the increase in friction and corrosive activity. In addition, sludge and debris would also be built up.

  • ​7. Shaking or Grinding
  • A vehicle runs smoothly when there is no jerk, shake or grinding noises, which all result from an issue with the gears. Generally, grinding sound is a way of indicating problem in the manual transmission. If the engaging of shifting and clutch takes place, you should replace or adjust it.

    An automatic transmission is different. It takes more time shifting a gear compared to usual smooth transitions rather than making a grinding sound. In worse situations, the transitions would become more jarring and shaky.​

  • ​8. Humming, Clunking and Whining
  • When the transmission gets hot, it would generate different sounds such as buzzing, humming or whining, depending on car models. In a mechanical transmission, these noises are more abrupt, mechanical and louder. When you shift a gear, a clunking sound occurs. The differential or constant velocity joints the source if the clunking is coming from the underside of the car.

  • 9. Response Lacking
  • Generally, the moment when you shift the vehicle from parking to driving, it must go into the suitable gear. However, it would not happen in some situations. In an automatic transmission, there will be a delay when the gear shifts. For a manual transmission, there is the similar response, but the engine will increase its RPM after shifting into the gear. As a result, the car would not move and generate strange sound as it is going on, which means that you need to replace the gear.

John Henry
 

I am John Henry and I have begun to work in automotive industry since the 90s, specializing in car rebuilding and repair. After nearly two decades of working in this complex section, with extensive experience in repairing, troubleshooting and maintaining thousands of cars, I started to work as an auto blogger to share my practical knowledge as well as skills with car owners all around the world through a wide range of articles in online magazine.

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