[RS3100]

No different to many other modern cars I'm afraid. The clutch slave cylinders are made with plastic bodies and parts and can be prone to failure. Several post on here from owners who have had a failure. Mine has just gone at 17K miles and 7 years. The new component is a modified part, but as far as I can see externally the only difference appears to be a gaiter around the return spring and cylinder. Whether that's to stop dirt getting into the piston or clutch fluid leaking out, who knows

It's not a cheap repair, as the gearbox has to be removed to access it, and depending on the damage, may also require a new clutch and perhaps flywheel if they've been contaminated. The Ford Focus also suffers similarly and shares parts with the V40, but I've seen the same issues with other brands such as VAG.

 

[RS3100]

Thanks for the reply. No horror stories then. More to do with luck and how the car was treated. With that mileage I just hope the previous owner was an elderly couple or a lady and didn't drive it too harsh.

I'd say luck and poor choices by manufacturers. There are only a few companies that produce the clutch components. Volvo use Luk, but even if you go for another brand they all make extensive use of plastic mouldings because it's cheaper than metal.

As I said above, 17K from new, ex advanced police driver, never driven hard or abused, always double declutched and the clutch itself shows no abnormalities or excessive wear. The new clutch disc friction material has an overall thickness of 9mm. The old disc has 8.83mm constant around the circumference. But the slave cylinder is leaking from the piston bore, so either the seal has gone or the piston is scored, possibly as a result of dust from the clutch entering the bore. I guess the metal particles in the friction plate material are harder than the plastic and rubber, hence perhaps the external gaiter on the revised slave cylinder

But many cars have no issues. Those that do appear to be significant in number, compared to random chance though.

Having said that, I wouldn't let it put you off. Other marques have similar issues. Frying pan or fire?

 

[RS3100]

I drive 2011 c30 right now and these have similar slave cylinders afaik. Had absolutely no issues with gearbox during 9 years of owning the car. It seems all I can have is hope Will be carefully listening to any funny noises from transmission. Thanks.

I noticed a very slight weep of fluid from the bellhousing drain about 18 months ago. Hardly worth a mention, and didn't seem any worse at the last service. Earlier this year the clutch pedal started occasionally sticking down or not returning fully and was getting worse. The car has not be used for 3 months as we were abroad. Now I'm home I decided to investigate and fix it before putting the car back on the road.

I'd say that clutch pedal misbehaviour is likely to be the first symptom of slave cylinder failure, either that or a sudden drop with no return at all due to complete loss of fluid. Any funny noises are likely to be something else entirely.

 

[RS3100]

That's probably the reason for the bellows gaiter on the new cylinder then. Having stripped mine down, it's been leaking very slowly from the end of the piston bore by the release bearing. I could see where fluid had been sprayed around the inside of the bell housing by the rotation of the bearing, but the clutch disc and pressure plate don't appear to have been contaminated. I've changed them anyway. Dust from the friction plate material was stuck to the leaking fluid on the slave cylinder body under the release bearing and around the bell housing, so it could have been a combination of increased friction and loss of pressure I suppose, the latter perhaps also caused by dust from the friction material contaminating the seal in the cylinder bore. Either way, if the return pressure is inadequate when the pedal spring has pivoted to help depress the pedal, it will stick anywhere between about half way to fully depressed.

You can see the dark band of fluid and dust particles around the inside of the bell housing in the photo.