10 Most Common Transmission Problems & How To Fix Them

You’ll often hear ‘transmission’ and ‘gearbox’ used interchangeably. The transmission/gearbox unit is responsible for:

  • Transmitting power from the engine to the wheels
  • Ensuring reliable acceleration
  • Smoothshifting through the gears

Put simply, you’re not going anywhere without a working gearbox.

There are hundreds of moving parts in a transmission, plus wiring and electronics sensors in abundance. Left unchecked, transmission problems can accelerate from ‘strange noise’ to ‘very expensive problem’ faster than a Ferrari on the autobahn. But there’s good news! If you know the signs, you can get on top of gearbox servicing before it becomes a bigger problem.

Early signs of transmission problems

Every car, manual or automatic, has a transmission. Automatic transmission servicing is a little more involved because there are more electronic sensors to navigate. But with our expertise and your early diagnostic capabilities, we can shift servicing into high gear and get you back on the road sooner.

Top 10 common transmission problems

1.    Leaking fluid

Transmission fluid keeps the moving parts lubricated. Unlike engine oil, transmission fluid isn’t burned off.A low fluid level almost always indicates a hole that needs to be plugged.

Leaking fluid is one of the easiest transmission problems to recognise because the signs of a leak are obvious:

  • Fluid deposit on the driveway
  • Car drives fine but has problems reversing

Testing for low fluid in an automatic transmission is straightforward. Take the car for a short drive, park on level ground, raise the hood and check the transmission fluid dipstick. If everything is fine, the fluid will be a bright translucent red and smell sweet. If it looks dark or has a burned smell, or the fluid level is low, book an automatic transmission service straight away. Otherwise your engine could seize up on the road.

2.    Can’t get into gear

It’s probably obvious that a gearbox not changing gears is a bad sign. You might have a fluid level problem, be using the wrong transmission fluid, or it could be something else entirely:

  • Shift cables or clutch linkage need to be adjusted
  • Computer system not communicating with shifters

Check the fluid first. Manual transmissions normally don’t have a dipstick; in fact, checking the transmission oil level can be tricky. We recommend you contact S&G Gearboxes for gearbox servicing if you’re worried about low transmission fluid.

3.    Gears slipping

So your fluid level is fine, but your transmission keeps ‘slipping’ in and out of gear. Manual transmissions should never go out of gear until you perform a shift. Gear linkage parts can wear with age, causing your car to slip into neutral.

Automatic transmissions use a computer to change gears, which means servicing for aslipping automatic transmission involves diagnostics in the garage.

In both cases, gear slippage is a serious safety issue. You should book in a service immediately before your vehicle becomes a danger on the road.

4.    Noise: Clunking, whining or humming

As a rule of thumb, any unusual noise coming from the engine requires attention. Transmissions have lots of moving parts which means it can be tricky to identify the source. You know your car better than anyone, so if you hear something that doesn’t sound right then it’s time to book in for gearbox servicing.

  • Automatic transmissions are more likely to whine or hum
  • Manual transmissions announce problems with clunking noises, especially changing into first gear at the lights

5.    Grinding or shuddering

You might feel the signs of transmission problems before you hear or see them.In a manual gearbox, grinding during shifting could mean a clutch problem or worn synchronisers. Synchronisers or ‘synchros’ align the speed of the gears you’re shifting between for a smooth shift.

Automatic transmissions can begin to shudder between gears, which you will feel as a jarring sensation – like the way a learner driver might ‘bunny hop’ their first time in a manual car. This is a sure sign that automatic transmission servicing is overdue and you should book in to see our mechanics immediately.

6.    Burning smell

Burning smells are never a good sign in an engine with so many moving parts and combustible fluids. Usually what you’re smelling is burning transmission fluid, caused by an overheating gearbox. It could be caused by:

  • Dirty transmission fluid
  • Low transmission fluid
  • Leaking transmission fluid

Any of these can cause significant damage unless they are fixed early.

7.    Slow acceleration response

If your car is hesitating between gears or slow to take off from the lights, it might be a worn clutch (in a manual transmission) or something more sinister.

Hesitation is a common reason people book in for automatic transmission servicing. We need to get under the hood to accurately identify the fault and fix it, because there could be any number of reasons your throttle is slow to engage:

  • Faulty clutch component
  • Worn clutch springs or plates
  • Problems with the master cylinder
  • Air in the fluid channel
  • Combination of problems

8.    ‘Check Engine’ light is on

This bears repeating: never assume your check engine light has come on for no reason. Modern cars have loads of electronic sensors tuned to pick up vibrations, faults, jerks, and mistimed engines before you notice an issue.

Check engine lights are an early warning system. Some newer cars can give you more information, but in general you should book in full diagnostic service as soon as the engine light comes on.

9.    Noisy neutral

Lumpy or loud idles can creep up slowly. You may not even notice your car is loud in neutral until someone else points it out. This could be a transmission fluid problem, or it could be a mechanical fault:

  • Worn bearings
  • General wear and tear
  • Worn out reverse idler
  • Worn gear teeth

Whatever the cause, noise in neutral is almost certainly related to transmission problems.

10.  Clutch dragging

Dragging is common in manual gearboxes, and occurs when there is too much slack in the clutch pedal. This means the clutch and flywheel fail to disengage, so you can’t change gears even with the clutch depressed.

Although this is a serious problem (you can’t change gears, after all) the fix is relatively straightforward for a professional gearbox service team. We can usually tighten the clutch pedal without replacing any parts, lowering service costs and keeping you safe on the road.

How S&G Gearboxes can help

We are gearbox servicing experts, but that’s not all we do. Using advanced diagnostic equipment and high-quality parts, S&G Gearboxes take care of your car from engine bay to exhaust – and everything in between.

There’s no transmission problem we haven’t seen during almost 40 years in business. That means when you drop your car off for a service, whether it’s a brand-new automatic transmission or vintage manual, it’s in good hands.

Get in touch to learn more about gearbox servicing or pick our brans about a specific transmission problem.