TD4 Hard to push clutch pedal

The gears engage ok but the clutch pedal is heavy (or hard). 2001 @ 107,000 miles and probably running on all original from new parts. Makes my leg ache! any ideas?

Thanks

Might be worth changing the clutch cylinders to see whether that makes a difference - about £50 or so. They often have issues and need replacing.

Could be the clutch master cylinder. That's the easiest and cheapest bit to replace.

If it's the slave cylinder then do the clutch as well, as the cylinder's located inside the bell housing. Long (and expensive) job if it is that one, I'm afraid: front subframe off, rear prop and front driveshafts off, IRD off before you can even consider taking the gearbox out.

I'd get a proper diagnosis done if I were you and make your decision on that basis.