Quick Facts About Transmission Problems
- Transmission trouble may stem from low fluid, a worn clutch, or internal mechanical or electronic problems.
- Grinding, slipping, jerking, delayed engagement, and unusual noises are common warning signs.
- Some issues require only minor service, while others may call for a rebuild or complete transmission replacement.
A vehicle’s transmission is an incredibly complex component. A quick internet search for “transmission interior parts” returns an overwhelming number of images of assorted gears, clutches, converters, strange-looking bearings, and shift levers, all of which must work in harmony to get you down the road. The transmission transfers power from the engine to the wheels, so even minor issues can affect your vehicle’s safety and reliability.
If your vehicle has been making unusual noises or performing irregularly, you may be wondering if it’s time for a new transmission. While some transmission problems can be fixed with repairs, fluid service, or component replacement, others may signal the need for a complete transmission replacement. Transmission types can be categorized broadly as manual and automatic. A continuously variable automatic transmission (CVT) is another type, but we aren’t including it here.
Manual Transmissions
Manual transmissions require a host of ancillary components to facilitate gear changes. It is generally controlled by the clutch system, which disconnects the engine from the drivetrain to allow quick, smooth gear changes. Most clutch systems use a single clutch disc or a series of discs, and over time, these components will wear. If you press the accelerator pedal and the engine rpm increases but the vehicle speed does not, the clutch may need an adjustment or replacement. Here are some common issues that point to the clutch system as the culprit.
Manual Transmission Clutch Problem Signals
| Problem Signal | Diagnosis |
| Chattering or Scraping | If your clutch chatters when the clutch pedal is depressed, it could need something as simple as an adjustment. The worst-case scenario is a loss of clutch friction material from the disc’s surface. You may feel a vibration or pulsing in the clutch pedal. |
| Grinding | This is a common sign of a clutch disc or throw-out bearing failure. Throw-out bearing replacement typically requires removing the transmission. |
| Rattling or Clunking | A rattling noise may come from the clutch disc or a dual-mass flywheel within the flywheel. Replacement flywheels can cost between $400 and $1,000. Rattling can also indicate the shedding of clutch disc-facing material. |
If the vehicle needs a new clutch, the repair commonly includes replacing the clutch disc(s), pressure plate, and the throw-out bearing. The flywheel may also need resurfacing or replacement, as well as the pilot bearing or bushing. The cost for a new clutch can range from $1,000 to $3,000.
Manual Gearbox Woes
The reason we spent so much time on clutch diagnosis is that manual transmissions are typically less troublesome. As long as you maintain the proper fluid level and follow the manufacturer’s service recommendations, the most common problem plaguing the transmission gearbox is misuse of the clutch, which can cause the synchronizing collars to malfunction.
If your transmission won’t go into gear or pops out of gear while you’re driving down the road, it is probably a synchronization problem, which could lead to repairs involving shift forks, individual gears, and internal bearings. In this case, the repair cost can vary widely. One technician noted that he charges $800 for a manual transmission rebuild, plus parts. Some gear clusters could cost up to $500 each.
Automatic Transmissions
Automatic transmission issues are far more complex than manual systems due to the greater number of parts. These units contain about twice as many components and require careful assembly due to tight clearances and sophisticated electronics.
Automatic Transmission Problem Signals
- The vehicle is slow to move after shifting into Drive or another forward gear.
The first step is to check the transmission fluid level, if your vehicle has a transmission dipstick. Make sure your vehicle is on a level surface before measuring. Follow the procedure in your owner’s manual, which may require checking the fluid with the engine running and the transmission warmed to a specified temperature. The dipstick will show the proper fluid level range and may identify the required fluid type. If the fluid level is low, this could be the problem.
If you don’t see a dipstick under the hood, your transmission may use sealed fill and drain ports. If that’s the case, you’ll most likely need to visit a professional.
- The vehicle does not move when it shifts into a forward gear
In extreme cases, the fluid may be so low that the vehicle will not move at all. Follow the steps above and add only the specified amount it the fluid is low. If the vehicle doesn’t move, seek the help of a pro.
- The vehicle bucks and jerks when driving
This can result from transmission, engine, or electronic-control problems and should be diagnosed promptly. If there is a diagnostic code, a scanner may help identify the problem. A trip to the repair shop is in order.
- The vehicle slows down despite pressing harder on the gas pedal
A slipping transmission may be the cause. The internal transmission clutches could be at fault, but a component called a band, on transmissions that use them, can cause the transmission to slip and drastically reduce efficiency.
The fact is that automatic transmissions work well most of the time. But when they act up,the problem may involve internal compenents, hydaulic controls, sensors, software, or other systems that require professional disagnosis. Use our Service and Repair Pricing Guide to learn more about transmission repair costs and to find a repair shop near you.
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Editor’s Note: We have updated this article since its initial publication. Cam Benty contributed to the report.