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quick clutch cylinder diagnosis
https://www.ausmini.com/forums/viewtopic.php?f=2&t=38489		 Page 1 of 3
Author:  Shard [ Thu Dec 06, 2007 12:22 pm ]
Post subject:  quick clutch cylinder diagnosis
So I go out to do a routine clutch bleed today because clutch was a lil on the soft side. Attach hose kit, undo bleeder a turn get into cabin, pump 5 times, go have a look at reservoir and notice hardly any fluid has come out. Undo bleeder another notch, go back to push pedal but stand half outside car so I can see fluid and notice nothing is coming out. Tighten bleed screw and pedal has no resistance.

Oh great.

I've disconnected the metal pipe on top of the master cyl, if I pump the pedal and no fluid comes out of the top of the cylinder is it safe to say my 6mth old or so clutch master is dead?
Author:  Mike_Byron [ Thu Dec 06, 2007 12:59 pm ]
Post subject: 
No not safe to say that

To work a clutch hydraulic system must be a closed system - to bleed it you need to create some pressure in the line and then bleed it.

If you cant have someone opening and closing the bleed nipple (or pumping the pedal ) then get a cheapy supercrap one man bleed kit with a one way valve. Mere dollars - say less than $20.

You may have (and probably do) have hydraulic problems but the way you were doing it is not the way.

PS - I bought a new clutch slave cylinder from Tony Cullen at minisports just a few weeks back - next day delivery and from memory it was less than $60.

Mike
Author:  Shard [ Thu Dec 06, 2007 1:04 pm ]
Post subject: 
I've got one of the one way bleed kits that's what I was using.

Initially one pumps worth of fluid came out and then nothing after that.

Clutch was working fine apart from being a bit soft even today when I moved it from street to driveway.

I pulled the bleeder off the slave and put it in the top of the master cyl, attached bleed hose and still nothing so i'm leaning to the seals inside have died right? Off to mitcham to go get a new kit + flex hose sigh.

edit: forgot to mention that I did check the clevis pin and rclip and they're working normal (ie. clutch master pin thing is getting pushed up when pedal is pushed in).
Author:  gibovski [ Thu Dec 06, 2007 1:22 pm ]
Post subject: 
I can't imagine that your master cylinder decided at that exact moment to completely stop working. If your seals are gone you will still pump fluid through just fine if there is no resistance, eg a clutch spring fighting against it.

Might be a mechanical problem inside the master cylinder.
Stupid question but you do have plenty of fluid in the reservoir?
Author:  Shard [ Thu Dec 06, 2007 1:34 pm ]
Post subject: 
Yeah plenty of fluid in the reservoir. I agree it seems bizarre strange it'd stop passing fluid right when I go to move it after working fine getting the car offstreet onto a driveway; but I don't know what else it could be.

Given the pin is sliding up and down the master ok all I can think of is one of the seals has maybe torn completely or something strange so that the MC isn't pumping any fluid at all.

Using the bleeder off the slave that's isolating the MC from pedal -->MC-->bleed right? So if something wasn't broken inside the MC I should be getting some fluid out of the bleeder no? First time i've had a MC fail on me like this and I need the car sat so i'm hoping a rekit fixes the problem (haven't got time to pul the MC apart and look before going and getting a kit before link closes).
Author:  Shard [ Thu Dec 06, 2007 5:10 pm ]
Post subject: 
Well got a kit for it and have my master pulled apart, it wouldn't leak anything when I turned it upside down so I had to drain it via the reserve cap.

The rubbers look fine on the piston bit and there's nothing I can see damage wise along the piston shaft. Going to give it a clean, is it possible somehow that crud got into the reservoir and is blocking intake?
Author:  Shard [ Thu Dec 06, 2007 7:51 pm ]
Post subject: 
what a crap waste of a day.

Rekitted M/C, fitted new flex hose, put everything back together, bolted it all in and still nothing through the bleed valve.

There is an air hiss escape so the MC is building up pressure and pumping, it's just refusing to pump fluid.

Stuck and I have no ****ing idea. Stupid car can sit out there till Jan when i've got some $$$.
Author:  mikkis37 [ Thu Dec 06, 2007 8:13 pm ]
Post subject: 
Was having a similar problem a few weeks ago after pulling clutch apart for a rebuild. We thought it was the Master cylinder but turned out it was the slave cylinder. It didn't leak fluid at all but the piston inside it had collapsed. After replacing it everything worked fine. Replace the slave before the master and is cheaper too
Author:  Shard [ Thu Dec 06, 2007 8:14 pm ]
Post subject: 
If it was the slave wouldn't I be getting fluid out of a bleeder on top of the MC still?
Author:  mikkis37 [ Thu Dec 06, 2007 8:21 pm ]
Post subject: 
Good point should really read it all as I go. Is the arm moving at all when you pump the peddle?
Author:  Mike_Byron [ Thu Dec 06, 2007 8:25 pm ]
Post subject: 
Shard
No !!!!!!
Again, a hydraulic system needs to be sealed to pump fluid. Now, nip up the things you are calling the MC bleeder. Squeeze the pedal slowly, wait a second or two and release the pedal - do this a couple of times and then undo the thing you are calling the bleeder on the MC. DO this with pedal down.

You will get fluid !!! Doing it your way you are pumping the fluid out and then sucking it back. Now nip it up again.

Now, that we know the MC is working - go to the bleed nipple on the slave. Undo it so that you know it undoes and then does up. Nip it up again.

Repeat the slow pump as described above. With the pedal pressed down, undo thje slave bleed nipple to let out the air and traces of fluid and then nip up. Repeat until no more air is being expelled and that the clutch throw arm is moving properly.

Do it my way and then tell me the outcome.
Mike
Author:  Shard [ Thu Dec 06, 2007 8:25 pm ]
Post subject: 
No. After it stopped sending out fluid i'm guessing it sucked in a crapload of air and because it's not pumping out fluid I can't get air out of the system. There isn't enough fluid pressure to move the arm. Infact because the MC isn't outputting fluid there's stuff all fluid in the system except for the reservoir.
Author:  Shard [ Thu Dec 06, 2007 8:29 pm ]
Post subject: 
Mike_Byron wrote:
Shard
No !!!!!!
Again, a hydraulic system needs to be sealed to pump fluid. Now, nip up the things you are calling the MC bleeder. Squeeze the pedal slowly, wait a second or two and release the pedal - do this a couple of times and then undo the thing you are calling the bleeder on the MC. DO this with pedal down.

You will get fluid !!! Doing it your way you are pumping the fluid out and then sucking it back. Now nip it up again.

Now, that we know the MC is working - go to the bleed nipple on the slave. Undo it so that you know it undoes and then does up. Nip it up again.

Repeat the slow pump as described above. With the pedal pressed down, undo thje slave bleed nipple to let out the air and traces of fluid and then nip up. Repeat until no more air is being expelled and that the clutch throw arm is moving properly.

Do it my way and then tell me the outcome.
Mike


I don't have a bleeder on the MC. I tried using the slave bleeder on the top where the metal pipe comes out.

If I hook everything up properly so it's a closed system, I still can't get the MC to pump anything out of the reservoir (not even a little bit of fluid with a ton of air).

If I hook up my hose with valve to the slave bleeder and open it a bit, I get no fluid but I get a bit of air pressure because it makes an air pop noise when I remove the hose.
Author:  Morris 1100 [ Thu Dec 06, 2007 8:36 pm ]
Post subject: 
You have to get all the air out.
If the cylinder is off the car just place your finger over the hole where the pipe goes and push the piston in, the piston will displace a little air.
Let your finger off the hole to let that tiny bit of air out and replace your finger over the hole and let the piston out.
Repeat till all the air is out.

Cheap one man bleeding kits are useless. They just do not work. :evil:
Author:  Mike_Byron [ Thu Dec 06, 2007 8:40 pm ]
Post subject: 
Yes - now we are on the right track - exactly as I was saying. When you get the "pop" air with the pedal pressed down you nip up what ever you have undone and repeat the the process. Sooner or later it becomes fluid. Once you have fluid there you move to the slave cylinder and bleed it from there.

Just keep on repeating the pump, pedal down, undo bleed nipple to release air and air combined with Brake fluid process, Nip up the nipple with the pedal still pressed down and repeat process again until no more air in the system.

Mike
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