Signs of Transmission Problems, and Why You Should Act Now

Mia Bevacqua
March 2, 2018

Signs of a failing automatic transmission

  • Illuminated warning lights: The transmission control module (TCM) — a type of computer — oversees automatic transmission operation. If it senses a problem with the transmission, it will turn on the check engine light. It may also turn on the “reduced power” warning light and put the vehicle in “limp-home mode.”
  • Noise: Bad automatic transmissions can make many different noises. For example, grinding in a certain gear often indicates a bad planetary gear set. A whining noise that increases with engine RPMs can indicate a failed transmission front pump.
  • Rough shifting, delayed shifting or slippage: Automatic transmission problems can result in several types of shifting issues. These can be caused by something simple, like a shift control solenoid, or something more serious, like internal pressure loss.
  • Leaks: Automatic transmissions can leak from various locations. Common leak sources include the pan, output shaft seal and front pump seal. You may notice transmission fluid on the ground under your car. Fresh fluid is red, though it may turn orange-ish or reddish-brown as it ages.
  • Vehicle won’t move: If the car starts but won’t move, the transmission may be at fault. A catastrophic transmission failure can keep the vehicle from moving, or may only let it move in certain gears.

Signs of a failing manual transmission

  • Clutch problems: If your clutch is slipping, when you press it, your engine may rev without moving the car faster. This may mean your clutch is worn out, or that the pedal needs adjustment. If yours is acting up, get it inspected.
  • Hard shifting, clashing gears or jumping out of gear: Manual transmissions can suffer from several types of shifting issues. For example, worn synchronizer rings or gear teeth can cause hard shifting, gear clash or jumping out of gear.
  • Noise: Faulty manual transmissions can make many different noises. These include whining, growling and grinding. Whining is often caused by a low fluid level. Growling may be due to worn bearings, and grinding can be caused by worn gears.
  • Leaks: A manual transmission can leak from a handful of locations. Some of the most common spots are the drain plug and output seal. For manual transmissions, gear oil is the most commonly used fluid, though some use regular engine oil or automatic transmission fluid. Gear oil and engine oil tend to be brown, while automatic transmission fluid is usually red.
  • Vehicle won’t move: If the engine runs, but the car won’t move, the transmission may be to blame. A catastrophic transmission failure can result in a vehicle that doesn’t budge, or may only move in certain gears.


What the transmission does

The transmission has one main responsibility: transmit the power from the engine to the wheels so they can move the vehicle. The energy required to get the car moving and keep it going varies, and the transmission makes this easier by using gears. Low gears are for low speeds; as the car gains speed, it uses higher gears. 

With manual transmissions, you manipulate the gears using the clutch and gear shifter. You start in first gear, cycle up as you gain speed, and then back down as you slow.

All that work is taken care of for you with an automatic transmission. While your job as the driver becomes easier, the automatic transmission is anything but simple. Using a various sensors and solenoids, a computer and hydraulic power, the automatic transmission will identify the correct gear required and shift into that gear on its own.

What to do about transmission problems

Transmission problems tend to be expensive — especially if you’ve got an automatic. There’s a lot of labor involved and the parts themselves are quite pricey. So, before you assume the worst, make sure to get your issue diagnosed. If you catch a problem early enough, you may save some money.

Once the mechanic has diagnosed the issue, he or she can tell you whether your transmission needs to be rebuilt or replaced. Consider getting a second opinion. If that confirms the worst, you’ll have to decide whether it’s worth it or if you should get another car instead. Get an estimate from your mechanic for the transmission work. Then figure out what your vehicle will be worth, both with and without a functioning transmission. If you have an older vehicle with a lot of miles on it, it may not be worth fixing.

It’s a good idea to have your transmission cooler flushed after any automatic transmission repair. The torque converter should also be replaced. Manual transmissions should have the clutch set replaced, and the flywheel should also be resurfaced or replaced.


Mia Bevacqua

About the Author

Mia Bevacqua is an automotive expert with ASE Master, L1, L2 and L3 Advanced Level Specialist certification. With 13-plus years of experience in the field, she applies her skills toward writing, consulting and automotive software engineering.

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