Bongo Fury

I guess it''s possible that a similar situation could exist at the slave end. If this seal is worn, then perhaps the fluid could make its way past it - the 'weight;' of the clutch pedal pressing on the fluid could be enough to gently trickle the fluid past the seal. The piston stays put...

It's 30+ years since I dealt with this problem, but I clearly remember it was characterised by a need to pump up (as T a t'M says) the pedal rapidly in order to be able to use the system. If you rested your foot on it. the pedal slowly went down. There was no fluid leak to the exterior. I think it is most likely as T a t'M says but without seeing it etc. I wouldn't know.

Trouble at t'Mill wrote: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.

I had this scenario on a bike brake. Slow constant pressure and the lever would pull back to the bars - no fluid loss - it circulates to the reseviour, but a hard pull would operate the brakes.
Clutch pedal must be weighty enough (and/or the spring is broken???) to be causing this.

Sounds like the piston seal wont last too long now!

mikeonb4c wrote:It's 30+ years since I dealt with this problem, but I clearly remember it was characterised by a need to pump up (as T a t'M says) the pedal rapidly in order to be able to use the system. If you rested your foot on it. the pedal slowly went down. There was no fluid leak to the exterior. I think it is most likely as T a t'M says but without seeing it etc. I wouldn't know.

If the pedal goes down like that there HAS to be a leak to outside the system - you may not be able to see it, but it's still there.

No leak no creep.

I think you may be confusing BRAKE master cylinders - two circuits - two separate pistons - two separate systems all in the same housing, with a CLUTCH master cylinder a much simpler device - just one circuit - one piston and the single fluid inlet hole is only open when the cylinder is at rest.

The more I consider the problem here, the more it points to the slave cylinder leaking. Overnight fluid leaks and drains out due to gravity and that draws the pedal down until pressure is restored by pumping the pedal.

So the question is this.

Is the fluid level low in the reservoir?

Hi Guys,If you look at the drawing for the master cylinder you will notice it is not a run of the mill system.
I think ther might be some sort of shut down incorporated.

Only a thought.

Mal..

scanner wrote:So the question is this.

Where Is the reservoir?

Fixed it for you

teenmal wrote:Hi Guys,If you look at the drawing for the master cylinder you will notice it is not a run of the mill system.
I think ther might be some sort of shut down incorporated.

Only a thought.

Mal..

scanner wrote:

mikeonb4c wrote:It's 30+ years since I dealt with this problem, but I clearly remember it was characterised by a need to pump up (as T a t'M says) the pedal rapidly in order to be able to use the system. If you rested your foot on it. the pedal slowly went down. There was no fluid leak to the exterior. I think it is most likely as T a t'M says but without seeing it etc. I wouldn't know.

If the pedal goes down like that there HAS to be a leak to outside the system - you may not be able to see it, but it's still there.

No leak no creep.

I think you may be confusing BRAKE master cylinders - two circuits - two separate pistons - two separate systems all in the same housing, with a CLUTCH master cylinder a much simpler device - just one circuit - one piston and the single fluid inlet hole is only open when the cylinder is at rest.

The more I consider the problem here, the more it points to the slave cylinder leaking. Overnight fluid leaks and drains out due to gravity and that draws the pedal down until pressure is restored by pumping the pedal.

So the question is this.

Is the fluid level low in the reservoir?

Hi Scanner,I think that was the original question JAKI asked (Where is the Reservoir)as she bought fluid to top it up if required.
Cheers Mal..

spout wrote:

scanner wrote:So the question is this.

Where Is the reservoir?

Fixed it for you

Fixed what?

That isn't what I asked.

scanner wrote: So the question is this.

Is the fluid level low in the reservoir?

That is indeed the question. All the rest is academic debate (which we all love on here, much to the bemusement of the casual enquirer )

Jaki, I wonder if the '2 parts' the garage said they'd replace were the master and slave cylinders?

I've just realised that garages these days wouldn't entertain a repair of these parts - they'd either go for brand new (very expensive) or reconditioned (still costly...)

Worth a call to Bell Hill Garage? They can probably lay their hands on lowish mileage used parts and should be able to say pretty accurately what sort of costs are involved.

I bet they could also diagnose the fault over the phone.

Trouble at t'Mill wrote:Jaki, I wonder if the '2 parts' the garage said they'd replace were the master and slave cylinders?

I've just realised that garages these days wouldn't entertain a repair of these parts - they'd either go for brand new (very expensive) or reconditioned (still costly...)

Worth a call to Bell Hill Garage? They can probably lay their hands on lowish mileage used parts and should be able to say pretty accurately what sort of costs are involved.

I bet they could also diagnose the fault over the phone.

The reason most garages replace rather than repair parts is because they tend to get shafted by joe public when the problem reappears in a few months time, especially with brake/clutch cylinders if there's a minute scratch in the cylinder and the new seal leaks again. Joe Public kicks up a fuss and the garage end up replacing the parts as a goodwill gesture. Believe me - I've been there! Fit new cylinders, they're guaranteed for a year and the jobs done properly

The worst one I had was when we replaced a clutch on an old Rover. Within a month the slave cylinder began to leak - customer not happy! He paid for the part and we fitted it free. Within another month the master cylinder seal failed - customer really peed off - he wasn't for telling! The reality of it was the cylinders couldn't cope with the strength of the new clutch spring - we ended up fitting a new master cylinder F.O C.

Thats when I learned to advise them to either replace the lot or expect possible trouble. Problem then is the garage next door won't advise that and quote cheaper for the job "Next door are just trying to rip you off" says next door, come to us - we'll do it cheaper..............................can't win eh????

Thats one reason I packed in the retail trade and retrained to be a teacher in the topic........................

Hi Dandy.

Yes, I fully understand - I wasn't meaning it as a 'slight' on mechanics.

Any repair to these components must be carried out in a perfectly clean environment, and I can imagine mechanics being a bit wary of doing this kind of job - any error/ ingress of dirt particles could have serious consequences (I'm thinking of braking systems).

Also, with labour costs almost always being the highest proportion of a repair bill, there probably wouldn't be any financial advantage in having it repaired over replaced in any case!

Trouble at t'Mill wrote:Hi Dandy.

Yes, I fully understand - I wasn't meaning it as a 'slight' on mechanics.

Any repair to these components must be carried out in a perfectly clean environment, and I can imagine mechanics being a bit wary of doing this kind of job - any error/ ingress of dirt particles could have serious consequences (I'm thinking of braking systems).

Also, with labour costs almost always being the highest proportion of a repair bill, there probably wouldn't be any financial advantage in having it repaired over replaced in any case!

The labour to strip it down clean it and reassemble would be more than the extra cost of a new cylinder.

In the past, purely as a get you home measure, I have used engine oil instead of hydraulic fluid - the extra viscosity is enough to eliminate the leakage for a while.

Yes, that's the point I was making.

Are the rubber seals used in braking systems and engines different in some way, because I was always led to believe that any contamination by engine oil of the seals used in braking systems etc. could cause them long-term damage?