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The hydraulic fluid in my clutch master cylinder disappeared - no clutch action. After moving the PCM and verifying that the reservoir had an exposed inlet, I read up on the system in the service manual.
I checked the actuator cylinder underneath at the flywheel housing and inside the firewall behind the clutch pedal - no leakage evident. I wonder where the fluid went after 22 years? I assume it evaporated.
There is a rubber moisture barrier in the shape of the reservoir well which seals under the cap. If I fill the reservoir to the "full" line, this rubber barrier will obviously displace the fluid unless it is collapsed. There is no evidence of how this should be configured such as in a brake master cylinder with the "accordion" or "bellows" effect. It is not described in the SM.
Can someone suggest the proper procedure and configuration to replace this rubber piece with a full reservoir?
2nd question - the book says to use a special DOT 3 GM clutch fluid to prevent squeaks. Is this absolutely necessary, or could I use some fresh brake fluid?
.....
There is a rubber moisture barrier in the shape of the reservoir well which seals under the cap. If I fill the reservoir to the "full" line, this rubber barrier will obviously displace the fluid unless it is collapsed. There is no evidence of how this should be configured such as in a brake master cylinder with the "accordion" or "bellows" effect. It is not described in the SM.
Can someone suggest the proper procedure and configuration to replace this rubber piece with a full reservoir?..../QUOTE]
The 'hat' shaped rubber clutch reservoir moisture barrier does NOT collapse.
This photo shows the brake reservoir moisture barrier collapsed, and the clutch moisture barrier in the natural state:
The clutch master cylinder in my 1994 vette moisture barrier looked exactly like yours, like a top hat. I figured it had to collapse because the fluid would overflow when I tried to put it back to together and I couldn't see the fluid level marks to know if I had enough fluid. So I collapsed it and it looked normal and the clutch has worked fine since I did the work 6 months ago.
94corvetteC4 - "The clutch master cylinder in my 1994 vette moisture barrier looked exactly like yours, like a top hat. I figured it had to collapse because the fluid would overflow when I tried to put it back to together and I couldn't see the fluid level marks to know if I had enough fluid. So I collapsed it and it looked normal and the clutch has worked fine since I did the work 6 months ago."
Congratulations on collapsing the moisture barrier.
You are not the first to do so. About 10+ years ago.
this same topic was debated on this forum between those with single-digit IQs who collapsed the cap,
versus those who knew the cap did not collapse.
Yes, I tried collapsing the cap, until I realized the cap was not designed to collapse. I'm a slow learner.
If you don't collapse the cap you can't read the full-low marks and their is barely any room for fluid.
Congrats on joining the single-digit IQ club. You are
not alone.
I guess I belong to the "club".
I will enthusiastically accept that membership if only someone can please explain how to put the lid back on the reservoir after filling it to the full mark (about 1/2 way up), with the top hat barrier configured as a top hat, and avoid having the fluid displaced (as in spilled out over the top) as the barrier and lid are pushed down to meet the threads?
Jack, place the moisture barrier outside, or inside, of the reservoir so that you can judge approximately how
much fluid can be added, or any other method you so choose to determine the fluid level. Use a marker pen to note the level.
Add fluid to the approximate level. Wrap a rag around the reservoir to capture the excess/displaced fluid as you position the barrier, and thread the cap.
Once the cap is threaded, it is recommended that you use two slip-joint pliers, one to secure the cap, and one to hold the reservoir from being twisted off from the plumbing while tightening the cap.
If you were to read Richard Newton's book, 101 Projects for Your Corvette 1984-1996, you would see in Project 29 - Clutch master and slave cylinder replacement: "the hydraulic system is self-bleeding, and non-adjustable". Then you would read numerous paragraphs about bleeding the system.
Thanks for the tips on bleeding. However, something still does not seem right - when I add just a 1/4 inch of fluid into the reservoir, which is well below the "add" and "Full" marks, just placing and screwing on the top with the fully extended rubber barrier into the reservoir pushes most of the fluid up the sides, and out the top.
Then, when you stick a finger into the barrier after removing the top, it seems to be bottomed out on the reservoir. When the barrier is removed, there remains fluid in the small area below the entry hole into the master cylinder bore, and the hole itself is exposed without even the smallest fluid head (which the rubber barrier displaced).
I talked to an "older" mechanic I know at the dealership, and he stated that they would just leave it out, and used to just fill the reservoir to the top - end of story. I won't just buy this at face value, however.
I long for the days of pedal free play and sore knees! Lots less work required under the car!
Jack, note post #4 by 'Herb'.
He left his barrier out, and "no problems".
Owned my '93 6-spd ruby for 12 years, and only removed the cap to check fluid level.
Never had a problem replacing barrier.
The barrier is designed to be there for a reason by very smart people. It is your vette, do as you wish.
Sympathize with the knees, as my '92 is an auto.
I agree with the smart people comment, which is why am reluctant to leave the barrier out.
I wonder about collapsing it to halfway, then placing it on top of a properly filled reservoir, while "hoping" it does not recharacterize before the cap gets tightened?
Old vette you might not want my advice since I'm a retarded single digit IQ guy but this is what I did and it works. No overflowing brake fluid getting into your engine bay and on your floor and no guess work required to know if you have enough fluid to begin with. Fill the resivoir with fluid to the full mark. Collapse the hat and put it into the cap. Thread cap onto resivoir and tighten by hand. Your done.
It will look like this.
I did this 6 months ago and no issues. Fluid level is perfect and hasn't changed. Clutch works perfectly.
I did not know this was possible, either, because if it were this obvious, I never would have bothered the forum.
My "top hat" is straight-sided, with no evidence of "fold points", bellows or accordion potential or evidence that it has ever been collapsed a la brake master cylinder seals. When I attempt this with the clutch hat, it won't stay in a collapsed configuration very long - let alone the nice, neat configuration shown in the recent pictures. If I get it to half-way with significant distortion, it may stay long enough to jam it into the reservoir before it opens out again.
I will volunteer for the low-end of the single digit IQ score if I can get this solved.
Mine didn't look like it was ever collapsed either. I folded the sides in from the bottom and pushed down as I was folding and it went into that position.
Mine didn't look like it was ever collapsed either. I folded the sides in from the bottom and pushed down as I was folding and it went into that position.
Did anyone else have a hard time getting the lid off of the reservoir? I've tried and tried and can't get it to budge. My hands are not large, but I cannot get a good grip on it. The way it is on there, I'm afraid that I will break the reservoir. Any tips?
01-07-2016, 09:45 AM
93 Clutch cylinder fluid
