Hydraulic clutch absorbing air?

[NickCLotus]

Hi,

Noticed the gear-change was getting a bit more notchy on my Peugeot 307 so have just bleed the clutch, now much improved. However, it was only a year (2.5k miles) ago that I did it last time.

Any thoughts at to why the clutch hydraulics seem to be absorbing air?

Edited by NickCLotus on Friday 11th April 16:56

[GreenV8S]

Do you have a spring pulling the pedal up? Does it pull the pedal up far enough to connect the circuit to the reservoir? If it doesn't, then the circuit would remain under slight suction, which might encourage air to leak in past the various seals.

[NickCLotus]

GreenV8S said:

Do you have a spring pulling the pedal up? Does it pull the pedal up far enough to connect the circuit to the reservoir? If it doesn't, then the circuit would remain under slight suction, which might encourage air to leak in past the various seals.

Yes pedal spring is in place correctly.

[GreenV8S]

NickCLotus said:

Yes pedal spring is in place correctly.

Does it pull the pedal up far enough to connect the circuit through the master to the reservoir?

[SystemOfAFrown]

NickCLotus said:

Any thoughts at to why the clutch hydraulics seem to be absorbing air?

A poorly sealing seal in the slave or master cylinder can allow air to enter without leaking fluid. The (coaxial) slave in my mother's Yaris had this problem, only it got bad enough that bleeding was required weekly but it still didn't lose any fluid.

[NickCLotus]

GreenV8S said:

Does it pull the pedal up far enough to connect the circuit through the master to the reservoir?

I guess so, it dribbles out through the bleed nipple when opened so it must be connected.

[NickCLotus]

SystemOfAFrown said:

A poorly sealing seal in the slave or master cylinder can allow air to enter without leaking fluid. The (coaxial) slave in my mother's Yaris had this problem, only it got bad enough that bleeding was required weekly but it still didn't lose any fluid.

That sounds like the problem then.

[NickCLotus]

Something has just occurred to me, could it be that I am using damp brake fluid? Using the same 5l pot that have had for the past ten years but now wondering if that could have absorbed some moisture over time through the plastic container.

[steveo3002]

certainly worth using fresh fluid

[GreenV8S]

NickCLotus said:

Using the same 5l pot that have had for the past ten years

An unopened bottle should keep for years, but once opened it has a shelf life of about 12 months.

[paul_c123]

Well yes and no. Unlike the brakes, a clutch doesn't really heat up the fluid during normal use, so its not like the excess moisture in the fluid would turn to gas, then be more compressible, and cause "fading".

But still, that's very poor workshop practice to use 10 year old fluid. As above, really.