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Hydraulic gremlins

1013 Views 11 Replies 6 Participants Last post by  nogtv, 
nogtv
OK, 87 Spider Graduate, 54.7K. Just replaced all flex lines for brakes and clutch, discovered the 20 year old master cylinder was a bit tired so replaced that also. Finally got the system bled, thank you bb, and the brakes are fine. Now I meet the clutch gremlin. Replaced the flex line, bled the master and slave cylinders now there is no clutch pedal! I have found that if I pump the clutch pedal 5-6 times I get resistance and clutch but the release is instantaneous, obviously not correct. Bled system with cap off, hose immersed in fluid until no bubbles, than tighten the bleeder while the pedal is depressed. Anything wrong here or am I dealing with worn hydraulics?

Also have signs of fluid collecting at the bottom of the booster then dripping onto floor. Could there be fluid in the brake booster from the previous leaking brake master cylinder? If there is, how the heck is it getting out of the booster? There has been no apparent drop in fluid level, yet.
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ghnl
I've always found it difficult to bleed hydraulic clutch systems. Even more so than brake systems. It seems like you are trying to push air downhill (well, because you are...).

What works for me is to fill a 60ml syringe with brake fluid and attach it to the bleed screw with a short length of hose then open the bleed screw and push the fluid in & up to the master cylinder. This way one is pushing air 'uphill'. (be careful not to allow the master to overflow - brake fluid is a good paint remover) Also, make sure the bleed screw on the slave cylinder is upper-most "12 o'clock" to get all air out of the slave cylinder.

You don't have a failing clutch pedal pivot do you? Have a look at these pages: Droopy Clutch Pedal & Replacing the Clutch Pedal.

re: brake fluid from the booster - a leaking master cylinder can indeed allow brake fluid into the booster. If you are certain the fluid level is stable then it may well be left over from the old master cylinder.
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rogerspeed
Sometimes the clutch will self bleed by just pumping. Did you replace the flex line with rubber or metal? I got two new rubber lines one after another that were defective, when you pressed down on the clutch the line would swell like it had a a cyst. Another trick to bleeding the clutch is to manually, from underneath the car, work the clutch fork back and forth to pump the slave cylinder by moving the piston through the clutch rod. If you remove the master from the booster use a syringe/baster to suck out the fluid that has acumulated in the booster from a leaky master.
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C
Is the clutch pedal at or below the level of the brake pedal? This sounds like it could be a pedal pivot on it's way out...same thing happened to me on my 87 Grad.
Don't know about the brake booster fluid issue.
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nogtv
Both pedals are dead even and high. When I first get in the car during the day, I can push the clutch pedal to the floor with zero resistance. I started the car and gently tried to engage any gear, no can do...everything in there is spinning. Yet, if I pump the clutch pedal a few times I have a clutch, the more I pump it the more clutch I have. I've never experienced this in any previous cars including two Alfas.
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C
2
Those are the exact symptoms mine had...turns out my pivot was bent/twisted, and not completely broken.
Here are the two pivots to compair.

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ghnl
It does sound like there is still air in the system. Try re-bleeding. Try propping the clutch pedal in the 'down' position over night (put a board or broom-stick on it) and re-bleed it the next day. (that sometimes helps bleed a motor cycle clutch - tie the clutch lever to the handle bar over night).

Hopefully it is not a failing clutch pedal pivot arm. It is a lot more work to get that pedal pivot replaced. However, if it is, get a stronger version here.
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nogtv
ghnl said:
It does sound like there is still air in the system. Try re-bleeding. Try propping the clutch pedal in the 'down' position over night (put a board or broom-stick on it) and re-bleed it the next day. (that sometimes helps bleed a motor cycle clutch - tie the clutch lever to the handle bar over night).

Hopefully it is not a failing clutch pedal pivot arm. It is a lot more work to get that pedal pivot replaced. However, if it is, get a stronger version here.
Click to expand...
Should the cap be left off the master cylinder for the overnight position exercise?
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A
Slave orientation

Just want to check that when you bleed the clutch slave that the bleed nipple is in at the top of the slave. If not, just rotate the slave such that the bleed nipple is at the top of the slave. Good chance that's your problem. Good luck,

Adam
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ghnl
nogtv said:
Should the cap be left off the master cylinder for the overnight position exercise?
Click to expand...
My guess is yes - or at least loosely installed. I've not had to do this on any car I've worked on with hydraulic clutch. I've succesfully used the 'fill from below' method on MGA, MGB, & Peugot. The 'hold in the clutch lever overnight' method was advised for a Honda motorcycle.
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Alfajay
Nogtv had written: "Also have signs of fluid collecting at the bottom of the booster then dripping onto floor. Could there be fluid in the brake booster from the previous leaking brake master cylinder? If there is, how the heck is it getting out of the booster? There has been no apparent drop in fluid level, yet."

Yea, that's how master cylinders typically fail - the rear seal wears and stops sealing. The vacuum present in the booster draws fluid out of the MC, filling the booster. So sure, that fluid is the residual from your old MC. Before installing the new one, you should have used a turkey baster or some other suction device to remove the old fluid.

Does your booster still boost? It will die eventually - the presence of brake fluid eventually kills them.

So why is it dripping? Beats the heck out of me. That's why I asked if it still provides boost - might the moisture in the old fluid have caused it to rust out? If is is rusted out, then a) it would be leaking vacuum, and b) it might leak out the old fluid. But, if it does boost, then it should be vacuum tight, and as such, not allow brake fluid to leak out. The drip is puzzling. Especially since you say that the new MC isn't losing fluid.
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nogtv
Well I think the mystery is solved. The leak is apparently from the clutch master cylinder. It is slowly trickling down the booster, collecting on the outside bottom and dripping on the floor. I also checked and found the slave cylinder to be at 10 o'clock instead at 12 o'clock. I should have just replaced them both when I did the brake master. Something to do before the holidays.:)
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