Problems with clutch master

[RazorbackNOR]

Since I have overhauled both cylinders for the clutch, I now have to bleed the system to get rid of any air trapped in it.

That doesn't seem to go so good.....

Fluid is flowing from the reservoir, seals are newly installed(and triplechecked to assure both correct orientation and placement).

So I had the master of(again), and mounted it down in the workshop. Filled the inlet port with fluid and started pumping the piston. it seems to produce pressure and strangly enough more vacuum at the outlet port Pluging the outlet port with my finger produces so much vacuum that the piston does not fully retract and at the inlet port it doesn't seem to draw any fluid.

Allmost like the is a one-way-valve missing somewhere, but the seal shold be acting like one shouldn't they....?

Does anybody have any ideas of where something is wrong or if I'm doing anything wrong....?

Position when opening master



Anders cylinder when he overhaueld his


Mine as of now. From what I can see, they are all identical....

[Jon Weywadt]

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Does anybody have any ideas of where something is wrong or if I'm doing anything wrong....?

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You do have the hoses connected to the right ports on the Master cylinder, of course 

[RazorbackNOR]

He he 

Luckily there is no way of connecting these wrong, since the outlet(pressure) has the brakeline threads(M10) and inlet has M16.

[Bart_Maztra]

Since I have overhauled both cylinders for the clutch, I now have to bleed the system to get rid of any air trapped in it.
So I had the master of(again), and mounted it down in the workshop. Filled the inlet port with fluid and started pumping the piston. it seems to produce pressure and strangly enough more vacuum at the outlet port Pluging the outlet port with my finger produces so much vacuum that the piston does not fully retract and at the inlet port it doesn't seem to draw any fluid.

Doesn't sound wrong to me. When releasing the clutch pedal, fluid is flowing back to the master cilinder.  Fluid is pushed back by the pressure of the clutch-plate. But the spring in the master cilinder is also sucking the fluid back.  If there was a one-way valve, the fluid is not able to travel back, and the clutch will not release.


But bleeding the clutch line can be a pain.

I made myself this to make it easier:




Oh, and if someone is looking for a new hose between the reservoir and the cilinder, i can supply new for free, only shipping costs

[RazorbackNOR]

But bleeding the clutch line can be a pain.

Good to hear Bart. but wouldn't the vacuum in the lines draw fluid from the inlet port through the cylinder? Seems like your setup has the advantage of filling the lines without my problem of getting it past the seals.

Visited my local carparts shop yesterday(Biltema) and got hold of a pressure bleed kit. From what I understand, this uses air pressure to force the fluid up "the wrong way".

Will keep informed on further progress.

[RazorbackNOR]

YES!

Finally got the clutch bled.

The vacuumkit didn't work as I planed, I think that my compressor may have been a bit small in both pressure and airflow to maintain a high enough vacuum for this to work.
So I made a little workaround, removed the piston from the master cylinder, sealed the opening with a plug, so there was nothing to hinder the flow through and applied the vacuum at the slave.

For once, progress on the clutch came in abundance! At this night I also was working alone, and trying to manage the master cylinder, the compressor and the vacuum kit all alone was a bit of a hassle.

But once I had the pipes bled, I filled the master cylinder with fluid, inserted piston and lockring. now the slave was able to push the clutch like it was supposed to! 
There might be some airbubbles left in the master from this method, but for now it was the only way of getting this to work before the snow comes. Also tried holding the pedal down for a while(with engine running and gear engaged) and it didn't seem to slip, so guess it's as good as it gets for now.

No pictures of this one, since it gets dark around 16.00 nowadays, and this was done close to 21.30 still working outdoors.

[roy4matra]

Since I have overhauled both cylinders for the clutch, I now have to bleed the system to get rid of any air trapped in it.

That doesn't seem to go so good...

I realise you have probably fixed this by now but here is some information for everyone with Murena.

First, the Murena 1.6 and 2.2 use a different bore clutch master cylinder.  I point this out since I have found a 2.2 one on a 1.6 car, which will push more fluid and over-stroke the slave cylinder.  Conversely a 1.6 master cylinder on a 2.2 would not provide sufficient fluid.

Regarding bleeding after overhauling the master cylinder or slave cylinder, the main problem lies in the fact that these units were originally designed to have a metal pipe and unions but we have a plastic pipe instead.  To seal the plastic pipe ends in to the master or slave, they have used a small rubber sleeve.  Over the years, the pressure this causes on the plastic tube, causes it to become permanently narrowed in diameter.  When it is out, look carefully and you will see this.  Once you disturb this seal when removing the pipe from the master or slave cylinders, you cannot simply put the pipe back with a new seal as it cannot provide the tight seal with the tube now smaller in diameter.  This is why it draws in air and prevents you from bleeding the clutch.  You must remove the plastic tube inner metal support, cut off the narrowed end of the tube and re-insert the support.  Now the end is full diameter again, and will seal easily with the new rubber seal.

All this was detailed in a previous club magazine with photos.  This is the sort of useful information you get when you are a Matra club member :-)

Roy

[RazorbackNOR]

Some previous joker has replaced the plastic tube with this some time ago...



Is seems to have done the job thou, but not really looking good. When I had alll parts of, I replaced this with a proper banjo w/bolt, which should have more then enough passage through all of it. Despite this, I was not able to bleed the brakes the "normal" way.

Wil try to get a picture of the new setup on the car in storage.

[roy4matra]

Some previous joker has replaced the plastic tube with this some time ago...

So I noticed.  That is for the reservoir pipe connection and is not the one I was talking about.  It is the pipe between the master and slave cylinders that gets narrowed after some years and if not rectified makes it difficult to bleed the system.

Is seems to have done the job thou, but not really looking good. When I had alll parts of, I replaced this with a proper banjo w/bolt, which should have more then enough passage through all of it. Despite this, I was not able to bleed the brakes the "normal" way...

Under this connection are two holes from the reservoir feed down in to the bore and piston.  When this reservoir connection is modified, you have to be careful that neither hole is blocked but particularly the tiny hole.  I had to repair one for a customer, where the tiny hole had been blocked by black mastik or something similar!  That car would not bleed as the fluid could not pass through properly.  Once it was cleaned out, and the usual narrowed pipe end rectified, it bled fine.

Roy

[RazorbackNOR]

Some previous joker has replaced the plastic tube with this some time ago...

So I noticed.  That is for the reservoir pipe connection and is not the one I was talking about.  It is the pipe between the master and slave cylinders that gets narrowed after some years and if not rectified makes it difficult to bleed the system.

Is seems to have done the job thou, but not really looking good. When I had alll parts of, I replaced this with a proper banjo w/bolt, which should have more then enough passage through all of it. Despite this, I was not able to bleed the brakes the "normal" way...

Under this connection are two holes from the reservoir feed down in to the bore and piston.  When this reservoir connection is modified, you have to be careful that neither hole is blocked but particularly the tiny hole.  I had to repair one for a customer, where the tiny hole had been blocked by black mastik or something similar!  That car would not bleed as the fluid could not pass through properly.  Once it was cleaned out, and the usual narrowed pipe end rectified, it bled fine.

Roy

Ah, I see. Seems like someone allready has noticed the problems with this, since is has been changed to pipe som time ago.


Yes, I noticed these as well. Also measured to be sure that the banjo didn't block either of the holes. Could be that the small holes is not open enough, if it was I would guess that it would have sucked the necessary fluid through. Either way, I got enough fluid tin the system now, and it seems stiff enough to hold the clutch as is now.

[Oetker]

You need the hooked connection.
This connection wil trap air in the inlet pipe.
The original pipe between the brakefluidpot and the clutchmaster has that problem to.
I did this to make it better, but there is to little room for it.
Still thinking about something better.