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Question about clutch fluid and bleeding

I have old, ancient brake fluid in the clutch line that no doubt needs to be changed. Parameters: I am broke and alone (so almost no money and no helper for bleeding). Over the last few months, my clutch pedal has slowly sunk lower and lower and now the engagement point is in the very last inch or so from the floor. Everything above that is nothing with no resistance. Last winter, I had some problems with the clutch pedal sticking to the floor when it got very cold - and the cold weather is almost here. So my theory is that there is moisture in the ancient fluid and it froze at those times last winter. I also figure old crappy brake fluid would cause the pedal drop. I doubt there is air in there but that’s a possibility too. Anyway, I am having trouble finding the specifics of how to fully bleed the system by yourself. I know about the vacuum thing that costs $40 or whatever but my price range is more like the $3 for the new bottle of fluid and that is it.

I have been told that what I should do is just suck out the fluid in the reservoir and then fill it with new fluid and just keep repeating that once every few days for the next few weeks until the fluid is nearly all changed-out. Does that work? Does all the fluid just mix and circulate so that bleeding really isn’t needed using this method over time? If not, and the whole thing must be bled out and totally replaced with new fluid all at once - by myself - then what is the best method? I thought that the fluid in any given spot in the line or reservoir would not really move, just get pushed back and forth. So which is correct?

Maybe not. I suspect you have a bad master or slave cylinder, or both. That the pedal sticks to the floor more when it’s cold suggests that the cold is shrinking the internal seals enough to cause fluid to leak past them.

The solution will be to replace the bad cylinder (and really, the solution is to replace both of them because when one croaks, the other often is not far behind).

I’m sorry to say that this is almost certainly not going to be a $3 fix. If you do the work yourself and get the parts from Rockauto, you can probably keep it under $100, though.

I have been told that what I should do is just suck out the fluid in the
reservoir and then fill it with new fluid and just keep repeating that
once every few days for the next few weeks until the fluid is nearly all
changed-out. Does that work?

No, because the fluid isn’t being mixed around like that. It would be like saying “I don’t have to flush my toilet because I just skim the top inch of water off a few times and everything’s clean.” It doesn’t work that way because skimming off the top lets the stuff at the bottom stay at the bottom.

The correct procedure is to bleed the system through the slave cylinder. In some cars, like mine, the slave cylinder has a dumb feature: the bleeder nipple is not the highest point in the cylinder, which means you can’t get it bled unless you either use the vacuum tool you talked about or you take the cylinder off and turn it so that the nipple is at the highest point, then bleed it and re-install. Obviously, vac-bleeding is far easier and faster.

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Suck the old fluid out of the reservoir and refill with fresh. Then put a pan under the bleed screw and open it up and let it drip until new, clear fluid comes out. Close the screw and top off the reservoir.


Gravity bleeding works on some clutch hydraulic systems but not on others.

And from what you describe, it would occur after the clutch hydraulic master/slave were replaced.


If it has an external slave, it should work. How ever I am not confident that it will fix his issues, but he can do it on that $3 budget of his.

It’s probably going to be necessary to replace the clutch master cylinder at the minimum. But if you are trying to just get by spending and doing as little as possible, you could try just sucking out the fluid in the MC plastic bottle with a turkey baster, putting new in, then bleeding the system. No experience w/your make/model, but on my Corolla what I do is find a stick that is just the right length to depress the clutch pedal 90% of the way to the floor when I wedge it between the pedal and the seat. Once you got a stick of the right length, remove the stick and let the pedal go to its normal position. Open the slave cylinder bleeder screw, put a piece of hose on it so anything that comes out the end drips into a glass jar on the other end of the hose. Now use the stick to press the clutch pedal down and wedge it there. Some dirty looking fluid probably is now in the jar. So close the slave bleeder valve, then remove the stick and let the pedal back up. Repeat this process until the fluid runs clear. Check the plastic bottle on the MC to make sure it stays topped off. It doesn’t take long, maybe 15 minutes, to bleed the clutch system by yourself this way.

To be clear…the car is a 2001 Chevy Cavalier manual transmission. The whole clutch was replaced with a new one last year which includes the interior slave. There are no leaks at all anywhere around the outside of the slave, the bleeder or the master and the fluid level has not dropped at all - ever.

I have the bleeder valve all cleaned up, ready to crack open and a new bottle of fluid. I just would love to know if I can gravity bleed this thing without pushing the pedal down since I am alone. Again - no leaks, no loss/drop in fluid level in reservoir and the clutch works fine. The problem is that the pedal engagement point has gone from around the 50% point down to the last inch - around 10% from the bottom with the top 90% travel doing nothing. And yes, I have inspected everywhere for fluid at the top of the pedal inside too. Bone dry.

Since you said the clutch was replaced and the “interior slave” which sounds like the clutch master cylinder was replaced. That means it got new fluid a year ago so that’s not your problem. At this point I’d say the slave cylinder is failing.

I think you’re misunderstanding how brake / clutch cylinders can leak. It’s possible for them to leak internally. The setup is just a piston inside a cylinder. The piston has a rubber seal which fits tightly against the cylinder wall and serves as a blocker for the hydraulic fluid. If that rubber seal is damaged or degraded, fluid can leak past it. The fluid doesn’t drip out anywhere because it’s still in the system, but because it’s slipped behind the seal where it’s not supposed to be, the piston ends up not being able to apply hydraulic pressure to the system.

Picture a syringe, which works in a very similar manner. You fill it with medicine, then a rubber-lined plunger comes down and forces the medicine into your arm via hydraulic pressure. But if that rubber has a hole in it, it lets the medicine flow behind the plunger, so the medicine ends up staying in the syringe, and not going into your arm.

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Thanks very much for the replies.I have spent the last few days doing research and inspecting things more. Really still puzzled. The slave is inside the transmission and was part of the whole kit that was replaced last year. That’s what I meant by internal. I thought that the procedure for replacing the master - which I can buy for about $55 - would be a 20 minute piece of cake job. But the more I look at how in the world I am supposed to get to either the pedal connection on the master or the engine side of the thing - they both have tons of crap in the way that I can’t see how to remove. Assuming I could do that - I figured my only shot was to use the car’s breaker bar / tire iron to try and wedge it between the pedal and the drivers seat to try and bleed the fluid out alone.
Lots of people I’ve tried to describe the problem to misunderstand and think I mean that the pedal sometimes get stuck all the way down and stays there. That is not what is happening. Over the last 6-8 weeks, the point at which the pedal engages or disengages has dropped lower and lower so that I am afraid if it goes another half inch, I won’t be able to shift at all. Now I would think that is symptomatic of a fluid problem rather than a leaking (internal) master. But I’ve heard all sorts of theories. They would have had to put new fluid in there last year when the clutch kit was installed, right? Before that, I had never had anything like this ever happen before and that was with 15-year-old fluid so why would 18 month old fluid do this now?

anyway, thanks again for the replies

I think you just need to bite the bullet and replace the master, even though it sounds like a bear of a job.

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Generally you disconnect the rod at the clutch pedal, then the whole assembly is removed from the firewall side. If there are no bolts on the MC on the firewall side, then you just turn the MC CCW about an eighth of a turn to remove it.

BTW, I don’t think the issue is the master cylinder. I think your mechanic made a mistake and the clutch assembly will need to come out. Did you get a guarantee with it?

One more thing, is the MC completely full of fluid? If it is, remove a little of it and see if that works.

Replacing the clutch master cylinder on my Corolla is a bit of a challenge. Definitely not a 20 minute job. It’s positioned – by necessity – at a corner of the engine compartment. And the brake booster is right in the way, just to make things even more interesting. When I do that job, I remove the battery, the air cleaner ass’y, and the throttle body intake boot and associated stuff first. Then I undo the bolts holding the brake booster to the firewall, which allows me to push the booster a little to the side and yield enough clearance to access the clutch MC. Then there’s the challenge of removing the hydraulic tube and the MC bolts in that cramped area. I discovered by trial and error that a pair of long reach curved-tip long nose pliers are most helpful.