clutch failure
The clutch looks simple but it's a fundamental part of a car (Picture iStock/irman)

Clutch failure can leave you well and truly stranded The clutch is one of those parts of the car that many of us take for granted. That third pedal sitting to the left of the accelerator and brake is fundamental to how a manual transmission works.

That's where a bit of self-diagnosis can pay dividends. If you know your clutch is on its way out, you can book your car into a garage before it leaves you high and dry. And you can shop around to get the best deal possible.

The good news is clutches frequently don't just fail. There will be some tell-tale symptoms. Here's what you should look out for.

What's a slipping clutch?

The first thing to be aware of is what's known as clutch slip. When you select a new gear, release the clutch pedal and continue trying to accelerate, you'll notice the engine racing while you're not speeding up as fast as you normally would. When a clutch is slipping you may also detect an acrid burning smell and sometimes even see smoke.

What does a slipping clutch mean?

The clutch mechanism employs a plate or disc that uses friction to join it to the flywheel where they move at the same speed. If the friction material is getting towards the end of its life, the clutch plate will start moving at a different speed to the flywheel. This won't permit full engine power to be transmitted through the gearbox to the road wheels.

Usually a clutch will start slipping long before it fails. As soon as you notice it, book your car in to have it fixed. You'll be able to drive it there under its own power at a time that suits you and without the panic of being left unexpectedly car-less.

clutch failure
The clutch links the gearbox to the engine (Picture iStock/GregorBister)

What's a sticking clutch?

The opposite problem to a slipping clutch is when the clutch plate
won't release from the flywheel. The input shaft to the gearbox is still turning and that makes it tricky to get the car into gear without a grinding noise. Sometimes you can't get the car into gear at all.

What causes a clutch not to release?

In days gone by, there was a cable that linked the clutch mechanism to the pedal. This could stretch causing the clutch not to release. The cable has been replaced by a hydraulic mechanism employing slave and master cylinders. These can suffer leaks and other defects that prevent sufficient fluid pressure being built to release the clutch. Sadly, there's often not much warning before these problems strike.

Other sudden problems

Back in the day, clutch cables used to break, leaving you stranded. Sudden clutch failure can also be caused by problems with the pressure plates that squash the friction plate onto the flywheel. If the springs behind these plates fail, you might feel the clutch pedal go very heavy and then you'll lose drive.

Is it the clutch or gearbox?

You're in the car and struggling to select or change gear, is it the clutch or the gearbox that's at fault? There's a simple test you can perform that will identify either way. Turn the engine off and see if you can select a gear. If you can then it's usually clutch trouble; if you can't then the problem will lie with the gearbox or gear linkage.

How long do clutches last?

A clutch wears out through use. As with pretty much every other component on a car, how quickly that happens depends on how the car is driven. Treat your clutch with respect and you'll get more miles out of it; it's as simple as that. A clutch should last for 60,000 to 80,000 miles. But if it's been abused and slipped during its lifetime, that distance might be halved.

How much is a replacement clutch?

This is a major component and not cheap. For most family cars, you'll be looking at somewhere between £400 and £500 for a new clutch. But do shop around and you may pay less.

Scott Wilson is Green Flag's vehicle and customer insight manager