C5 Clutch bleeding

This is the Forum for all your Citroen Technical Questions, Problems or Advice.

Moderator: RichardW

bumpy001
Donor 2024
Posts: 9
Joined: 08 Sep 2023, 09:01

C5 Clutch bleeding

Post by bumpy001 »

Hello,

Quick question regarding the C5 clutch bleeding - if I use an Gunsons Ezibleed kit and apply a small pressure (a rew psi) to the brake master cylinder reservoir, should fluid come out of the bleed screw on the clutch slave cylinder once bleed screw is cracked open ?

It doesn’t in my case, only way to get fluid to come out the bleed screw is by pressing the clutch pedal and then bad things happen to pedal height.

There seems to be a single spring clip hold the metal hydraulic tube to the slave cylinder, don’t think it’s a complicated setup.

Thanks all.
Timmycitroen
Donor 2024
Posts: 18
Joined: 05 Dec 2023, 19:11

Re: C5 Clutch bleeding

Post by Timmycitroen »

Try wedging clutch pedal down to floor then put on ezibleed till you get good stream then crack off bleed screw
bumpy001
Donor 2024
Posts: 9
Joined: 08 Sep 2023, 09:01

Re: C5 Clutch bleeding

Post by bumpy001 »

Timmycitroen wrote: 30 Jun 2024, 19:11 Try wedging clutch pedal down to floor then put on ezibleed till you get good stream then crack off bleed screw
Okay, I can give that a go. Also people think the reverse direction bleeding is worth a go mostly because that pushes the fluid up hill.
I can try both these because I learnt some lessons this afternoon - see next post.
bumpy001
Donor 2024
Posts: 9
Joined: 08 Sep 2023, 09:01

Re: C5 Clutch bleeding

Post by bumpy001 »

All,
Right I learnt 2 lessons this afternoon, worth sharing, might help someone:

1) the bleed screw doesn’t behave like a conventional tapered seat metal bleed screw. That’s because it’s plastic O ringed affair. It’s possible to get it to pass fluid quite early on using clutch pedal ( high fluid pressure) - where it behaves a bit like a one way valve flowing only with high pressure behind it and resealing as pressure drops. BUT for a low pressure, like the easibleed, the bleed screw needs a good turn (probably 1 1/2 turns) for it to allow fluid past..

2) the brake master cylinder reservoir which also doubles as the clutch master cylinder is divided internally - no surprise there. I did get caught out by how small the clutch section is though - it is tiny. And whilst externally you can see the level of the main reservoir looking full, it is all too easy to empty the clutch reservoir.
Luckily the brake fluid on the car is so grotty and dark in colour it’s possible to show the empty portion :lol: Picture incoming when I get a minute.

Reading many posts on clutch bleeding problems I’d guess it’s point 2 that has caused quite a bit of bother. And further merit is added to the reverse flow bleeding method as it avoids the issue entirely.

Car drivable again within 30 mins once I’d learnt my lessons. :oops:

HTH

BMP
PaulC5
Donor 2024
Posts: 428
Joined: 06 Jun 2023, 15:26
x 104

Re: C5 Clutch bleeding

Post by PaulC5 »

I would not reverse bleed it since all the bits of rubber that wear off the seals will be pushed up into the reservoir and could end up in the brakes.

I have found the best way to bleed the clutch master/slave cylinder is to suck the fluid out through the slave cylinder bleed screw using a Mityvac pump. Pressing the pedal does not work well. A large syringe might also work. Some slave cylinders are bled by moving the position of some clips and pipe but on our C5 the bleed screw has to be undone a bit, just cracking it open is not enough for the fluid to flow. The reservoir outlet is quite high up for the clutch so the fluid level has to be kept topped up when bleeding or air will get into the cylinders.

The Mityvac I have is quite old now and not available but is similar to this one but I have modified a plastic container around 300 ml to use since the included reservoir is quite small and has to be emptied often https://www.uktools.com/mityvac-brake-bleeding-kit.html

I gave up using the Gunsons easy bleed a long time ago, I never liked putting pressure on the reservoir. I stopped filling it with brake fluid since it sprayed out a few times, it overfilled the reservoir and then any left inside had to be cleaned out. I also got fed up of having to pump the tyre up each time.
bumpy001
Donor 2024
Posts: 9
Joined: 08 Sep 2023, 09:01

Re: C5 Clutch bleeding

Post by bumpy001 »

Thanks Paul for your pointers.
Regarding reverse bleeding I agree with your concerns about wear debris heading into brake reservoir, I reasoned that having forward bleed already, most of the debris has already gone. Refreshing contents of the brake reservoir would not go amiss….

I opt for approx 3 psi positive pressure on the brake reservoir applied with a Mityvac via the Ezibleed. I don’t like the Ezibleed really and don’t use it with fluid in it …. I’m using it as a small extra air volume and I rely on inspecting and refilling the brake reservoir.

The real benefit of Mityvac sucking the fluid through slave cylinder, it’s what happens to the air bubbles under vacuum. It’s fascinating to vacuum a jar of freshly poured brake fluid, what you thought was air free fluid, really isn’t. Vacuum bleeding is a good method.