Clutch pedal has no resistance - first things to check?

[ant_thomas]

Running a 64 plate Berlingo Van 1.6 HDI.
Got in it this morning after it had been parked on a steep hill in gear for around 36 hours.
I've done this a number of times recently without issue, obviously not today.
The clutch pedal had no resistance across probably 90% of the travel, with a small bit of resistance over the last 10%.

Managed to get moving, changing gear relatively ok. But it got gradually worse along the drive where I wasn't actually to deselect/select gears without some difficulty. Eventually drove around 30 miles home.

At no point during the drive did the clutch "slip". Once in gear it drove as normal with no issues.

Arrived home and the clutch/brake fluid reservoir is definitely empty.

Am I looking at a new clutch master cylinder or is it more serious?
What should I check first?

[cancunia]

I take it that the brakes are fine?
I'd top up the reservoir asap to stop any air getting into the brakes if it's a shared reservoir. The clutch is a fairly simple circuit, it may be the slave cylinder or the master, or the pipework in between. I'm not sure where the slave is on the 8v engines, but if it's the same as the 16v it's below the battery at the front. You need to see if there's any sign of fluid leak anywhere.

[ant_thomas]

As it happens I've been getting brakes/ABS/ESR warnings intermittently for a couple of weeks. I've had this on a previous car and the issue was around the sensors. Just assumed the same and was going to investigate fully on a dry weekend. Turns out this wasn't the issue.

Refilled the system and bled the clutch side of things. Fully repressured and it feels like nothing has happened, van back to normal. Clutch working fine. I'll keep checking the fluid level. There's obviously a minor leak somewhere, which could easily develop into a larger leak. But for the moment it is definitely driveable. I'll fully investigate the issue soon.

Refilling the system has resulted in no more brake warnings. Find it a bit lazy/stupid to have them both running off the same reservoir. Where a clutch issue could result in brake failure. I'm hoping there's some other failsafe in there to prevent something too dramatic but it feels like that could be possible.

[cancunia]

Agreed, it does seem a daft way to save a few pennies. Good to know it was an easy enough, if short term, fix.

[GraemeT]

Hello - brake pipe output from a shared reservoir is below the clutch so if your clutch leaks then you still should have brakes.

Your symptoms sound the same as we had with a (ptooey! Renault) - that was the clutch remote cylinder (ptooey! inside the bellhousing FFS). Start up, everything goes fine and then gets worse & worse until we ended up using the ancient art of double declutching up and down the gears or else just bung it in third and try not to stop.
Leave it overnight, next morning, all fine and then same old stuff.

No idea if your one has a master/remote setup or a master/cable - in either case check the clutch master cylinder seals - chances are that they are a bit worn so allow fluid to pass where it shouldn't.

[ant_thomas]

Kept it topped up, clutch still working but now the ABS/ESR warnings are back.
Will try and investigate further but may just bite the bullet and get it into the garage since there's clearly some issue that needs looking at properly.

[Sol]

If you get hold of a strong UV torch, I got one from the Tesco petrol station, brake fluid glows in a milky white fashion under UV. You need a dull area indoors or at night to really see it well, but it's worth a shot for a few quid to see where it's coming from.

There are dye / UV kits on eBay to trace brake fluid, oil and fuel leaks but I'm not keen on adding chemicals to my brake fluid. The torch by itself is good enough in a darker setting.