Clutch isn't bleeding...

[peterh]

Hi all,

I'm still working on getting my clutch working again. Unfortunately two hurricanes (Frances and Jeanne) have caused this to become a rather lenghty exercise. However the car is now back out from under all the other stuff that was put in the garage.

I rebuilt the clutch master cylinder with the rebuild kit and re-installed it. So far so good.

Then I went to bleed the system and after I got a little fluid out of the bleed nipple on the slave cylinder it just stopped. I can't seem to get any fluid to flow now. The system doesn't seem to be leaking anywhere so I am thinking that either it has an airlock in there or it's got some crud that is blocking it.

Any thoughts?

 

[Keoke]

Peter, remove the slave unit from the bell housing but do not disconnect it from the fluid lines let it hang and remove the bleed nipple from it and see if you can now get fluid to flow through it. If fluid flows the nipple is likely to be blocked. If no fluid flows using a screwdriver or what ever force the piston back in the clyn if fluid flows the flex line is probably bad-FWIW---Keoke

 

[screenprinter]

Peter,

Did you benchbleed the master cylinder? It's difficlut to evaculate all the air from the system if you don't do this before you re-install the master cylinder.

Please don't think I'm second guessing you, but is there any possibility the seals in the rebuild kit got installed with the lip facing in the wrong direction?

What Keoke suggested is the best thing to try first - If this doesn't remedy the situation try disconnecting all lines and hoses and blowing them out with compressed air - After years of exposure to brake fluid the inside of the flexible lines get gellied and swell partially shut - So that's a good place to start.

Good Luck

Bob M.

 

[peterh]

I removed the bleed nipple and cleaned it out. After doing this the fluid is flowing nicely. I have gone thru one 12oz can of fluid and am still getting no pressure.

Based on your comment about benchbleeding the master I am concerned that I might just keep putting fluid thru without getting the air out? Do you think I should remove the master again and benchbleed or do I just need to keep bleeding? Also could you explain how to benchbleed.

Thanks.

 

[screenprinter]

Bench bleeding is done before you install a new or rebuilt unit - It's easiest if you have a vise mounted on your workbench.
I protect the sides of the cylinder with thin pieces of wood and clamp the master cylinder in the vise with the clutch line end slightly elevated so any air will rise toward the line.
Often when you buy a replacement unit the manufacturer ships dummy lines and fittings to facilitate bench bleeding, if that's not the case you'll need to fabricate one which is nothing more than a spare fitting, short length of steel line assembled so that it looks like a clutch line which has been cut an inch or two after leaving the cylinder, some plastic tubing and a small hose clamp.

With the cylinder in the vise, screw the short line into the output end of the cylinder and then clamp a short length of appropriately sized plastic tubing to the end of the line.

Loop the tubing over the rim of the fluid reservoir and secure with a rubber band, twist tie, etc. Add brake fluid to the reservoir until the end of the tubing is well submersed in the fluid. When this is done SLOWLY push the operating rod of the master cylinder just like working the pedal would, Be gentle because fluid can fly everywhere if you're too enthusiastic.
You'll see air bubbles rising from the tube into the reservoir- Continue to pump slowly until no more air can be seen exiting the line.

with the reservoir fairly well full and the dummy line still in place, install the cylinder in the car and connect the pedal to the operating rod.

Remove the end of the bleed line from the reservoir but keep it screwed into the cylinder then cover the opening of the reservoir with a layer of sheet plastic and screw the top on securely. Carefully remove the dummy line from the output end and screw the real clutch line into the cylinder. The plastic over the reservoir should prevent massive fluid loss.

Proceed to bleed the slave cylinder making sure you never let the reservoir go dry. If all has gone as planned there should be no air in your system and you should have effective pedal - If not you have to track down what's going on - most likely a pinhole in the rigid line or a bad flexible line to the slave unit.
A hydraulic clutch is Hydraulics at it's most simple level - if the system is completely sealed, allcylinder bores, seals and pistons are in good shape and full of the correct fluid it WILL operate the clutch fork.

Let me know how it shakes out..

Good Luck!

Bob M

 

[aeronca65t]

I just went though a frustrating process of bleeding the clutch on my brother's Midget.
In the end, I discovered two pinholes...one in the metal hydraulic line and one in the flexible hydraulic line. I replaced both and the system bled properly after several attempts.
To bench-bleed a clutch master cylinder in the car, I just fill it with fluid and make sure the steel hyraulic line is removed. I have someone press down on the pedal while my thumb is over the outlet connection. Usually some fluid will spritz out past my thumb. As they release the pedal, I keep my thumb in position and it forces the cylinder to draw fluid from the resevoir. I do this several times and that usually does the job (I often do this myself, just using a stick to press down the clutch pedal).

 

[bob hughes]

When my slave cylinder seals packed in, I renewed the rubbers in both the slave and the master at the same time. I did not bench bleed anything, just lubricated the rubbers with a drop of brake fluid after assembly and got stuck in to bleeding straight away and all was OK. If you can lock off the nipple and still push the pedal to the floor without movement on the slave, one must seriously question if the master cylinder rubbers are properly installed. Always assuming that you are not leaking fluid through the pipes.
/ubbthreads/images/graemlins/cheers.gif /ubbthreads/images/graemlins/england.gif
Bob

 

[peterh]

Guys,

Firstly thanks for your help. I realised that I was in trouble when I couldn't even get the bench bleed to work. I took the cylinder apart but it was exactly like the diagram and matched by drawing perfectly from when I took it apart first time. However given that it still wouldn't work I knew something was wrong.

In a blinding flash of perspiration I realised that what had happened was that when I took it apart the first time the end seal had somehow become caught on the plunger where it actually fitted very nicely into the grove. I just thought that the end seal had disintegrated and was gone. So when I put it back together I added a new end seal but never removed the one that was now nicely fitted on the grove in the plunger.

So having removed that from the plunger the cylinder worked perfectly and now I can get the car back on the road...that is assuming that my hands recover from the gallons of brake fluid they have experienced over the last couple of weeks.

Thanks...Peter.

 

[screenprinter]

Glad to see that things came around Peter - It's not difficult to miss something like that and the good thing is it will definitely let you know something is not correct and won't come back around until you find it and remedy it.

Bob M.