I had a recurring problem with my cluth while on holiday - I have a good enough setup to go 250 to 300 miles between stops , but the longer I drive without using the clutch , the less it wants to work (if that makes sense ?)
The pedal (on first press) is `long' - it goes right to the firewall without releasing - but 5 or 6 slow presses and it's back to normal .
I have a 16mm integral master cylinder and a concentric slave cylinder - I changed the fluid (which was black...) , which helped a bit - but 2 days later I changed it again , and it was black again !
No leaks , no air in the system - and no clue as to what is wrong.................

if it black as you say then the seals are starting to go, time for a rebuild

i only know that as i have just had to rebuild my landy brake mc as it was starting to take a couple pumps of the pedal to get the brakes to work and the fluid was black

Is it getting too hot? Maybe DOT5 would work better?

I was wondering if it was heat related - the master cylinder is very close to the engine , and only a couple of inch's from the exhaust .
Odd thing is - use it constantly , and it's fine , so no problems around town , or up and down mountains , but leave it one gear and just drive and it goes away.................just clears off

What hoses are you using? the OE stuff can start to break down and cause the blacking of the fluid, it also goes soft with heat, and behaves like a baloon, when you press the clutch.

Sounds like at some time some oil contamination has got in the system --- it takes only a tiny ammount even WD40 destroys rubber seals even if it is wiped off the surfaces.

Fit clean & new seals in the master cylinder, you might get away without doing the slave.

[Edited on 5/9/10 by britishtrident]

Master cylinder rubbers on the way out. Sort it out now or it could fail at any time . Guess how I know!!

to test the seals

start engine

foot on clutch

select a gear

keep foot on clutch pedal and wait and see if it engages the clutch for you

if it does then seals are fecked

Im not an expert in hydraulics by any means, but surely if the oil (fluid) boils, then it would produce a gas, thus causing the effect that you describe as a result of an "Air" lock?

Personally, i think its heat that has destroyed the fluid after 2 days, which may also have done the seals.

quote:

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Originally posted by tomgregory2000
to test the seals

start engine

foot on clutch

select a gear

keep foot on clutch pedal and wait and see if it engages the clutch for you

if it does then seals are fecked

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quote:

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Originally posted by MakeEverything
Im not an expert in hydraulics by any means, but surely if the oil (fluid) boils, then it would produce a gas, thus causing the effect that you describe as a result of an "Air" lock?

Personally, i think its heat that has destroyed the fluid after 2 days, which may also have done the seals.

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quote:

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Originally posted by clairetoo

quote:

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Originally posted by MakeEverything
Im not an expert in hydraulics by any means, but surely if the oil (fluid) boils, then it would produce a gas, thus causing the effect that you describe as a result of an "Air" lock?

Personally, i think its heat that has destroyed the fluid after 2 days, which may also have done the seals.

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I did check the fluid level in the master cylinder at one stop , without pressing the pedal , and the level had risen significantly so you may be on to something there......

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I had this problem but without the fluid going black, no discernable loss of fluid but clutch was always shot in the morning but would work in a fasion when pumped up.

Turned out to be the slave in mine, it was leaking a tiny ammount of fluid out when left for any length of time.

It presented the same symptoms as a M/C fault, I even changed that before I admitted to myself it was box off time.

quote:

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Originally posted by MakeEverything
Is it getting too hot? Maybe DOT5 would work better?

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Did you get it sorted Claire?

What was the outcome~?