The bad news about the transmission in a car is eventually it is going to break down. Whether manual transmission or automatic transmission, it is a series of gears and other moving parts that operate mechanically and wear out. The good news is twofold. Changing transmission fluid according to the manufacturer’s specifications can dramatically increase the life of the transmission, and the transmission will usually provide plenty of warning before it gives out completely, stranding its occupants on the side of the road. Let’s talk about what a transmission actually is and some common signs the transmission in your car is going bad.
What Is a Transmission?
An automatic transmission is a complicated piece of machinery. The majority of vehicles sold in the U.S. are automatic. By 2016, only 3% of all vehicles sold here had manual transmissions, a steep decline from even five years earlier when 37% were available in manual. While stick shifts will remain on the roads in significant numbers for another five years or so, automatic transmissions will soon dominate.
An automatic transmission is a computer-driven shifting system with a complicated arrangement of independently and dependently operating gears that translate the power produced by the engine into rotational speed in the wheels. These gears are regulated by a torque converter that allows the gear ratios to change, much like a derailleur allows a cyclist to change gears on a bicycle. All this is lubricated and cooled by transmission fluid flowing through and around the moving parts.
The transmission is important for the same reason that gears on a bicycle are important: without it, the vehicle would operate in a single gear. That would make it difficult to start from a dead stop—especially on an incline—and it would burn out the engine at high speeds.
It is easy to see how this is true on a manual transmission: Put the vehicle in a middle gear and attempt to start it. The vehicle is likely to stall. Once it is running, leave it in that middle gear and speed up to highway speed. The car will complain loudly and might begin shaking. If the experiment were allowed to continue over an extended period of time, serious damage could be done to the transmission and engine; the vehicle could overheat and even if none of that occurred, gas mileage would be seriously compromised.
In the case of an automatic transmission, the transmission fluid’s primary task is to provide hydraulic pressure to turn some of the critical gears delivering rotational energy to the wheels.
A manual transmission is a simpler arrangement with the same purpose. In a manual transmission, the driver engages and disengages the gears using the clutch and manually changes them with the gearshift. Transmission fluid in a manual transmission vehicle is only needed to lubricate the movement of gears and cool the transmission.
The semi-automatic, or dual-clutch transmission is basically a hybrid of manual and automatic transmissions. It incorporates many of the same principles as the two discussed here. Semi-automatics are generally found on race cars and super-luxury vehicles and are not widespread.
The continuous variable transmission, or CVT, is unlike either a manual or automatic transmission in that it does not employ gears at all. It works like an automatic in that a computer controls the mechanisms, but its pulleys and belts provide an infinite range of gear ratios. CVTs are simpler than automatics and less prone to failure, and provide the smoothest response to road conditions, which leads to the best gas mileage. Because CVTs are more expensive to manufacture and repair, and noisier than other transmissions, they are not very popular.
Signs The Transmission in Your Car Is Going Bad
The most common causes transmission issues are related to operator neglect. Because of the critical role played by transmission fluid in an automobile, it is important to check the transmission fluid levels regularly. When the fluid is low or corroded it can do damage to the transmission, whether manual, automatic or otherwise.
Transmission Fluid Leaks or Corrosion
Fluid-related indicators serve as signs that the transmission requires attention. The most obvious is a leak. Red, sweet-smelling liquid beneath the vehicle is a tipoff that there is a loss of integrity somewhere in the system and liquid is dripping out. Confirm this is transmission fluid by checking its level and determining if there has been any loss. Transmission fluid can be found under the hood and measured via a dipstick. If the transmission isn’t showing any other issues, the solution is to repair the leak or leaks and refill the fluid.
If replacing seals that are causing leak points isn’t an option, an alternative option would be to invest $12.95 in sealant like BlueDevil Transmission Sealer that restores seals and gaskets to their original condition and stops leaks fast.
Using BlueDevil Transmission Sealer is easy and it works with all kinds of transmission fluid. Turn off the engine and pour the sealant into the transmission fluid container—one ounce of sealant for each quart of fluid. It will begin circulating as soon as the vehicle begins running and will take up to two days to seal leaks. Be careful not to overfill the fluid receptacle.
Assuming that solves the problem (BlueDevil offers a money-back guarantee), the only other consideration is to ensure the transmission fluid is refilled to the full line.
A second indicator of a possible transmission issue is the age of the transmission fluid. Particles can build up in old fluid and reduce its lubricating capacity, clog and corrode hoses, and gum up the gears. Transmission fluid should be changed periodically, as outlined in the vehicle’s owner’s manual. The interval is most often set at every 100,000 miles. If the fluid appears burnt or smells bad, it is time to flush it out and replace it.
A certified auto care shop flushes transmission fluid with a high-pressure hose to expel accumulated particles and debris. The filter and fluid are then replaced, and the pan is inspected and cleaned. A transmission flush costs $100 to $300 and can postpone or prevent repairs costing thousands.
Sometimes you can smell a fluid issue. A burning odor can indicate the fluid is past its expiration date and must be replaced immediately.
Difficulty Getting Into Gear or Gear Slippage
In manual transmissions, it may be difficult to get into gear, or the vehicle won’t move while in gear, or the transmission slips out of gear. These issues have a common set of sources, including the shifter, shifter cable or valve body. In automatic transmissions, slipping out of gear is likely a computer issue that requires a visit to the shop.
High-Revving Engine While in Gear
This issue often indicates the clutch or other parts of the transmission are wearing out. When this occurs, it is time for a checkup by a car care professional.
Odd Sounds From the Transmission
Humming, buzzing, clicking and racing are symptoms of a bad bearing or damage to critical gears in an automatic transmission. They can also indicate a bad seal, which can be repaired by adding a sealant.
Loss of Power in Gear
If the engine is running properly but the vehicle nonetheless lacks power while in gear, it is likely an error code in the transmission’s computer. This needs to be seen by a repair shop with the proper diagnostic equipment.
Grinding When Shifting
In a standard transmission, gears grind when the clutch is not fully disengaging them or the shift synchronizer rings are worn or broken.
An Unusual Feel with the Clutch
A clutch pedal that must be depressed all the way to the floor in order to shift a manual transmission suggests a problem with the linkage. It might need to be adjusted or the hydraulic fluid bled. A clutch pedal that engages with a light touch may indicate worn parts connected to the clutch, like the disc or pressure plate.
Need to Rebuild the Transmission
At some point, the transmission may just come to the end of its natural life, either because of neglect, hard driving conditions or time. The vehicle cannot operate without a transmission, leaving three options:
- Rebuild the transmission
- Replace the transmission
- Purchase a new vehicle
The last option may be worth considering, depending upon the age of the vehicle. New transmissions cost $3000 to $8,000 to purchase and install, with a rebuilt or remanufactured transmission at the lower end and a new transmission at the upper end. When a transmission is rebuilt, the worn parts are replaced and the working parts maintained. A remanufactured transmission is a used transmission with all new parts, usually resulting in a longer warranty. Remanufactured transmissions must be delivered to your local repair shop and often require a longer wait.
If you see any of these signs that the transmission in your car is going bad, your best bet is to seek out the advice of a qualified mechanic, especially if your car is automatic. If the diagnosis is that you need to replace the transmission, consider getting a second opinion, then decide if your vehicle is worth that kind of investment.