my clutch is on the floor every morning!!!!

[jaki&sue]

Every morning my clutch pedal is down to the lowest point, after pulling it up with my toe, it goes back down again, a few pumps of the clutch it comes to alighnment, but i cannot change gear, or even get into gear until i go through the process, The garage has said it is not the clutch itself, i bought some clutch/brake fluid but my English converted manual does not tell me where to put it, where is the resevoir for it please? and any idea what it could be. Garage has also suggested they will replace something that needs 2 parts and will be fairly costly, though at the moment i can't remember what they said it was called. any help for this tired woman would be gratefully recieved. thank you Jaki

[scanner]

Sounds like either the master or slave cylinder in the clutch hydraulic system is leaking and that is what they want to replace. If either/both have gone they will need to be replaced/repaired - no alternative.

Mine's an auto, so I have no idea where either is located I'm afraid.

[Trouble at t'Mill]

It might be down to excessive wear on the master cylinder piston seals, or possibly the slave. The former wouldn't necessary mean the fluid leaks out of the unit, but just by-passes the piston, rendering it ineffective.

Perhaps the remaining engine vacuum after switching off is drawing the piston down? Or perhaps the servo unit itself is malfunctioning?

(Lots of 'perhaps', I'm afraid.)

[teenmal]

It might be down to excessive wear on the master cylinder piston seals, or possibly the slave. The former wouldn't necessary mean the fluid leaks out of the unit, but just by-passes the piston, rendering it ineffective.

Perhaps the remaining engine vacuum after switching off is drawing the piston down? Or perhaps the servo unit itself is malfunctioning?

(Lots of 'perhaps', I'm afraid.)

Hi TAM,I think its the clutch pedal that is giving the problem.
Mal..

[scanner]

Perhaps the remaining engine vacuum after switching off is drawing the piston down? Or perhaps the servo unit itself is malfunctioning?

Yep as teenmal says it's the clutch not the brakes - no servo on the clutch.

[Trouble at t'Mill]

How embarrassing!

Ok, then - it's the first stuff I said!

One of the symptoms of worn or torn master cylinder piston seals is that when you apply a steady pressure to the pedal, it'll sink slowly to the floor. I can't really see the weight of the pedal alone doing this, but perhaps the return spring is broken allowing it to happen over many hours?

If you pump the pedal hard, it'll often temporarily 'seal' itself as the pressure of the fluid being pressed tends to press the edge of the piston seal tighter against the cylinder wall. So, a 'slow' press can be ineffectual, whereas a quick 'stab' can work.

By pulling the pedal back up yourself, the fluid is being drawn around from the 'wrong' side of the piston seal to the front - where it should be!

(Assuming it's a hydraulic clutch, of course. If it's cable, I'm stumped.)

Jaki and Sue, could the parts mentioned have been 'piston seals', 'rubber seals', 'master cylinder repair kit', etc?

(If the 'same' piston seals go in the 'slave' cylinder (ie: the cylinder at the clutch end which pushes the clutch open), then the unit will tend to leak with noticeable fluid loss. At the 'master' end, the fluid won't actually be lost, as the reservoir is there to hold the fluid.)

As most of us have automatics, we can't go out and look for the reservoir! However, they are almost always sitting right next to the brake reservoir, as the master cylinders are usually operated directly by the pedals. (I have heard of some unusual setups where the clutch cylinder is operated remotely by a cable due to lack of room, but I wouldn't have thought this would apply to the Mazda.)

[scanner]

How embarrassing!

Ok, then - it's the first stuff I said!

One of the symptoms of worn or torn master cylinder piston seals is that when you apply a steady pressure to the pedal, it'll sink slowly to the floor. I can't really see the weight of the pedal alone doing this, but perhaps the return spring is broken allowing it to happen over many hours?

If you pump the pedal hard, it'll often temporarily 'seal' itself as the pressure of the fluid being pressed tends to press the edge of the piston seal tighter against the cylinder wall. So, a 'slow' press can be ineffectual, whereas a quick 'stab' can work.

By pulling the pedal back up yourself, the fluid is being drawn around from the 'wrong' side of the piston seal to the front - where it should be!

(Assuming it's a hydraulic clutch, of course. If it's cable, I'm stumped.)

Jaki and Sue, could the parts mentioned have been 'piston seals', 'rubber seals', 'master cylinder repair kit', etc?

(If the 'same' piston seals go in the 'slave' cylinder (ie: the cylinder at the clutch end which pushes the clutch open), then the unit will tend to leak with noticeable fluid loss. At the 'master' end, the fluid won't actually be lost, as the reservoir is there to hold the fluid.)

As most of us have automatics, we can't go out and look for the reservoir! However, they are almost always sitting right next to the brake reservoir, as the master cylinders are usually operated directly by the pedals. (I have heard of some unusual setups where the clutch cylinder is operated remotely by a cable due to lack of room, but I wouldn't have thought this would apply to the Mazda.)

If it is leaking past the master cylinder seals how does it get back into the master cylinder reservoir?

If it's leaked past the seals it's out of the cylinder and either dripping down inside the bulkhead, or outside the bulkhead, dependent on how the cylinder is mounted.

If it's leaked - it's leaked.

[francophile1947]

Agreed scanner Whenever I've had a badly leaking master cylinder, the fluid has ended up all over my left foot
jaki&sue - where are you? If you put your location in your profile, somebody local may be able to look for you

[mikeonb4c]

T.a.t'M. is right I think. The seal he is talkng about is not a seal to the outside world (i.e. a gasket) but functions rather like (well is in fact) a piston ring (i.e. keeps fluid in the working section so it can be pushed down the pipe, prevents it leaking past the piston into the plenum area that includes the reservoir). I recall having this problem myself years back - no leak to exterior.

Shoot me down if I have this wrong

[scanner]

T.a.t'M. is right I think. The seal he is talkng about is not a seal to the outside world (i.e. a gasket) but functions rather like (well is in fact) a piston ring (i.e. keeps fluid in the working section so it can be pushed down the pipe, prevents it leaking past the piston into the plenum area that includes the reservoir). I recall having this problem myself years back - no leak to exterior.

Shoot me down if I have this wrong

BANG

The fluid leaks past the seal to the outside of the piston and is then held behind the rubber boot that keeps the bore of the cylinder clean eventually either the movement of the piston forces the fluid past the boot or the boot rots and leaks the fluid all over your foot as Franco remembers.

I repeat if it's leaked - it's leaked to outside whatever is trying to hold it in.

Just think of it as hydraulic incontinence.

[teenmal]

http://www.lushprojects.com/bongopartsm ... mgno=.html
This might help.

Mal..

[Trouble at t'Mill]

Hi, this is based on previous experience of this same problem on cars many moons ago!

Hard to describe, but imagine the clutch master piston sitting in its bore, with a round, tapered, seal on its shaft. The fluid reservoir sits above this setup, providing a constant supply of fluid. This main piston seal - the front one which drives the fluid down the cylinder and out the pipe at t'end - sits (I think) just behind the little supply hole from the reservoir when in it's 'resting' position. If needs be, fluid can come down from the reservoir in front of this piston seal to keep the level correct.

Then, when you press the pedal and this piston seal moves past this supply hole, it'll then start to press the fluid down the cylinder. If this seal is worn, then the fluid will simply force itself past the seal and find itself sitting behind the seal instead - where is has access to the reservoir.

There is then a second seal further up the piston shaft (towards the pedal end) which stops the fluid from actually exiting the whole cylinder. If you ended up with fluidy feet, then I guess it's this other seal that had 'gone'.

[scanner]

Hi, this is based on previous experience of this same problem on cars many moons ago!

Hard to describe, but imagine the clutch master piston sitting in its bore, with a round, tapered, seal on its shaft. The fluid reservoir sits above this setup, providing a constant supply of fluid. This main piston seal - the front one which drives the fluid down the cylinder and out the pipe at t'end - sits (I think) just behind the little supply hole from the reservoir when in it's 'resting' position. If needs be, fluid can come down from the reservoir in front of this piston seal to keep the level correct.

Then, when you press the pedal and this piston seal moves past this supply hole, it'll then start to press the fluid down the cylinder. If this seal is worn, then the fluid will simply force itself past the seal and find itself sitting behind the seal instead - where is has access to the reservoir.

There is then a second seal further up the piston shaft (towards the pedal end) which stops the fluid from actually exiting the whole cylinder. If you ended up with fluidy feet, then I guess it's this other seal that had 'gone'.

Exactly - but how does the fluid that has got past the first seal get back up into the reservoir?
And if it doesn't matter if the first seal leaks - what is the point of it?

[Trouble at t'Mill]

Oh! Extra posts!!

Yes, the other seal at the pedal end of the cylinder will (should) prevent fluid from actually exiting the cylinder at all times. When the OP releases the clutch pedal (or, should I say, pulls it back up...), then the main piston seal will, fairly easily, allow the fluid (which was in the wrong place) to flow past it to the front - it's a tapered 'one-way' seal (think of a bicycle pump - when you pump it down, you force the air out the end. When you pull it back out, you don't 'suck' the air back out of the tyre; fresh air is drawn past this tapered seal.)

Actually, if you do have a bicycle pump handy, try this: block the outlet with your finger and draw out the pump handle. Then try: pressing the handle down very slowly - I bet there's a good chance the piston will travel all the way down without too much effort because the air is slipping past the piston seal (like in the OP's clutch). If you try this again, but pumping quickly and hard (ooh-er, missus), the piston will seal and you won't be able to push it down.

[Trouble at t'Mill]

Scanner.

The cylinder has at least two seals. One sits at the very 'pedal' end of the cylinder and its job it to simply prevent any fluid from escaping the cylinder. This is a simple 'round' seal, with the piston shaft passing through it on its way to the pedal.

Then there is the actual 'main' piston seal which is a special shape - tapered like a cone so that fluid can pass over it when going in one direction but not t'other. The wide part of this cone faces 'forwards' towards the clutch. When you press the clutch pedal, this 'cone' seal shouldn't allow any fluid to slip past it. However, when the pedal is released, fluid can - if it wants to - get past it to the front of the piston.

As the actual clutch wears and the slave piston might need to move further to disengage it, more fluid might indeed need to move past this seal to get in front of the piston. There will always be fluid both in front and behind the main 'cone' seal - the end seal mentioned before stops it coming out of the whole contraption.

Any fluid behind the cone seal when the pedal is pressed has access to the reservoir, so when the pedal is released and the piston comes back up it'll force this fluid back into the reservoir.

Something like that, anyways!