1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Clutch hydraulic problems. Bleeding problems. Need help.

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Old 07-22-06, 08:04 PM
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Question Clutch hydraulic problems. Bleeding problems. Need help.

Two questions into one. How do you bleed the clutch system and what's my problem?

Okay, I have just installed a new clutch master and slave cylinder, along with a stainless steel line and hard line. Everything's on. Here's my problem: Apparently, I have either a leak or air still in the lines. I'll try to be as specific as possible.

First, I figured that bleeding the clutch system would be the same as bleeding a brake system, like a wheel cylinder. Have someone pump the pedal a few times, hold it to the floor, open up the bleeder valve to expel the air until liquid comes out, then close it and repeat the process.

Now, herein lies my problem. I do that and yet, everytime I went to open the bleeder valve and release any air and go to close it, the pedal remained at the floor. You had to manually pull it back up and then continue pumping it, which would bring pressure up. During this, I don't recall seeing the fluid level really going down in the MC. NOTE: The MC cap was off at the time, not on, if that makes a difference.

I also checked all the fitting ends and tighten them to ensure no leaks. I did spot a couple after pumping the pedal. Now, from what I can tell, no leaks, after tightening.

So now, after it was felt that I DID have pressure in the pedal, I took it for a small spin up and down the road by my house. The pedal does feel more "full", as it doesn't engage so soon once the pedal comes from the floor like it used to with the old stuff. After the test drive, I parked the car and checked the level. The fluid level was a bit below the FULL mark. Filled it to the FULL mark, and did another test drive. This time, when I pulled up to the driveway to turn around, I kept the clutch pedal all the way to the floor as I shifted into Reverse, let off it a bit and noticed that the pedal did not come off the floor. I quickly reached down, pulled the pedal back up, and shifted it into 1st, and quickly parked the car in the driveway.

So, what's my problem? I checked again after that "pedal to the floor" problem and did not see any leaks. Could there still be air in the system to have that problem? Also, how do I bleed the clutch system? Any/all help would be appreciated. This is my daily driver and I'll be needing it before the weekend's over with.
Old 07-22-06, 09:24 PM
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My clutch was doing the same thing and I bought one of the vacuum bleeders and it helped it bleed it very quickly. But Im loosing brake fluid somewhere so it still doesn't work


You can also look into the easy bleeder valves.

When I bled my clutch I had someone push the clutch to the floor with the valve open, and then shut it and had them lift it up and repeat.
Old 07-22-06, 09:58 PM
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Did that, still had the pedal to the floor until you lifted it back up. The Haynes manual says to have a helper to do the pumping action, but to also use a jar filled with about an inch of fluid in it, and to have a tube lead from the bleeder into the jar. So, I'll try that tomorrow, see if that works for me.
Old 07-22-06, 10:20 PM
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I went through about 2 pints of fluid and still had bubbles the first time with the slave mounted. It seemed near impossible to get the air out...

I then removed the slave cylinder, moved it higher than the highest hose in the system, put a clear tube on the slave bleed nipple, a C-clamp across the slave unit to keep the piston from flying out, and it took about 30 secs.... This put the air bubbles into the highest part of the system and also gave me something to push against (the c-clamp). Make sure you don't push too hard, just enough to get some load on the clamp.

I also had a stripped hole on one of the bolts holding the slave, I took a new bolt, cut it in half and put a metal wedge in there to get a 8.25mm bolt

Good luck,
Scott
Old 07-22-06, 11:46 PM
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I'm going to try the Haynes manual with using that bottle method. If that STILL doesn't work, then I might have to buy that $20 vacuum pump at Auto Zone to do it myself.
Old 07-23-06, 03:28 AM
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When you are bleeding, do you have a vacuum tube on the bleed nipple that goes into a container with brake fluid in it? This is the easiest method to prevent air from re-entering the system before the nipple is tightened.
Old 07-23-06, 07:27 AM
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I bought one of those $6 one man bleeding kits from Auto Zone. It comes with a small bottle with a cap that has one tube leading inside the bottle and another tube on the outside to place onto the bleed nipple. I tried using it before but didn't put fluid in it, so maybe that is my problem. I'm wondering if I should buy that hand vacuum pump instead.
Old 07-23-06, 09:59 AM
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Okay, I just went out, used that $6 one man kit, and low and behold, it actually worked. So, I made sure everything was tightened up, made sure that I saw clear fluid throughout the whole tube and then closed the bleed nipple. Took the car out for a test drive, using that clutch extensively, and parked it.

I checked the fluid level and I'm still losing fluid somewhere. The fluid was about 1/2" below the Full mark. I'm wondering if fluid is finding it's way through the (brand new) slave cylinder piston. I'll still be checking the fluid level through the upcoming days to check up on things.

Anyone else encountered this problem, or know a solution?

NOTE: Oh, when I did get my new SC, I put a small amount of fluid into it and pumped the piston a few times to prime it. I figured doing this would help it, like how the manual says to prime the MC. Did I do a mistake by priming the SC, and now fluid is leaking around the piston?

Last edited by 85 FB; 07-23-06 at 10:04 AM.
Old 07-23-06, 04:18 PM
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Factory manual says:

Old 07-23-06, 04:42 PM
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Already did that, as I did that in my previous post. Haynes manual said the same thing. Still noticed a drop in fluid level, tho no leaks around the fittings, after taking it for a test drive. So, I'll be checking it as I continue to drive it, and if needed, take it to the rotary mechanics and ask them what could be going on.
Old 07-24-06, 12:43 AM
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i wonder if it's leaking down inside the bellhousing.
Old 07-24-06, 08:21 AM
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Here is how you bleed the system.


open the bleeder, have someone press the peddle down and hold. Close the bleeder, You should see fluid leave the Master, do it again, Do it again.

Now Press the peddle and hold Open the bleeder, then close it, you should see fluid leave the master. Do it again, do it again.


With this procedure you bleed the line first and then bleed the slave.
Old 07-24-06, 06:32 PM
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Well, as I said before, I've bled the system just fine with that one man kit. Really simple once I realized that I had to put fluid in that bottle as well. I'm wanting to believe that I'm leaking inside the slave cylinder.

And, the slave clyinder does not connect inside the bell housing, it sits on top.
Old 07-24-06, 06:33 PM
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Well, as I said before, I've bled the system just fine with that one man kit. Really simple once I realized that I had to put fluid in that bottle as well. I'm wanting to believe that I'm leaking inside the slave cylinder.

And, the slave clyinder does not connect inside the bell housing, it sits on top, and has no way for the fluid to go inside it.
Old 06-13-08, 09:07 AM
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I am having the same problem with my friends RX-7 same year (GSL model) can't find the problem. Did you ever figure out what it was?
Old 06-13-08, 10:46 AM
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Everyone has a problem bleeding clutch hydraulics. Speed bleeders (a replacement bleed tit with a check valve) sometimes works. Sometimes the tube and bottle works. Sometimes a power bleeder that forces hydraulic fluid into the system works. One time there was a thread here from guys who'd improvised power bleeders (instead of paying $80 at the autostore) from everything from weed sprayers to bicycle tubes.

Persistence will payoff.
Old 06-13-08, 11:10 AM
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what i did at first (since i reinstalled my tranny, i had to bleed the clutch) press the clutch until the pedal fell on the floorboard, loosened the quick bleed valve on the slave and waited until liquid started to come out (took about 5-10 secs) then i had someone help me pump it and bled it just like you do brakes.
Old 06-13-08, 11:13 AM
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never mind ignore that post, :P i didn't read everything and realized that you'd already bled your clutch sorry.
Old 06-13-08, 11:21 AM
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Stop shaking up the brake fluid! its a no shake fluid!!

My word of advice is make sure once you have it all done that you dont have your clutch travel too far, or you will over travel the shaft on the slave that moves your clutch lever, and this can cause the rubber boot to fill with fluid. You will barely notice if your doing this because the travel stops as soon as fluid can serpt past often allowing the boot and force of the clutch to press it back to tolerance immediatly, or your pedal will stay at the bottom and your gonna be like WTF! (put it in neutral if your driving!). Their is also a clutch return spring attached to the pedal.

gl2ya
Old 06-13-08, 12:55 PM
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I replaced both cylinders on mine and finally have it working perfectly.

The first big challenge is getting most of the air out of the empty system and replaced with fluid. Otherwise the bleeding and pumping seems fruitless.

I got fed up and went to NAPA and bought a hand operated bleed pump that can create a vacuum or pressure.

First, make sure you prime the Master cylinder before you install it. Then, I used the pump and started at the bleed valve and pushed fluid up into the system. Then I pumped the pedal a few times to circulate everything. Then I topped off the master cylinder, and used the vacuum pump to suck fluid down through the system and into the pump's catch can. I operated the hand pump to generate the suction, opened the valve while pumping, and then closed it before I lost suction and got air in the lines.

I kept doing it until the fluid in the master cylinder started going down. Then I refilled the fluid and kept doing it until I didn't see any air going through the pump and only fluid went into the catch bottle. At that point, I was confident that most of the air was gone and the hydraulic system filled.

Then, I attached the bleed kit (tube & bottle) to the bleed valve and had my wife pump the pedal while I bled the clutch the normal way. Did that a few times and was shooting straight fluid with no bubbles. Then double check all your connections and make sure you haven't developed any leaks under pressure.

One thing to note, the master cylinder plunger is probably fully extended out of the box. Once you get the system installed and clutch bled and working, you'll need to adjust the pedal free play to get the proper feel and engagement point.

Once you do all this, you should be fine.
Old 07-12-08, 08:37 PM
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Romeo is bleeding

Ok, I searched and found this thread. Heres my 0.02, this thread was helpful and the closest match to my prob. none of the offered solutions helped directly however everybody did get the angry frustrated inventive juices flowing. So thank you.

In 20 years as a professional and home auto mech I have NEVER had to bleed a CMC. So todays the day and yesterday and the day before that. Yeah 3 friggin days.

Its always bothered me that the bleed nipple on a slave cylinder was below the main line. But I've never had to touch one so....

The two trans mount bolts were stripped so I JB welded the SC and kept moving. Then It came time to bleed. Ugly. I went through everything the OG poster went thru except i had the muzzel of the shotun in my mouth and my toe on the trigger when I was about to give up. Just then It hit me, a glimmer of hope. An idea.

Move the SC above the system. but that would involve breaking the JB weld, said the other scarier voice in my head. It worked like a charm ALL bubbles gone.

It also hit me that the SC wasn't hitting the bottom of its travel, doing it by hand ensured full travel and a butt load of bubbles at the end of travel of the SC. videos posted for the next guy that get hit with this as a new FB33 owner

now I just have to tap out the stripped tranny bolts an voila

<object width="425" height="350"> <param name="movie" value="http://www.youtube.com/v/RldyGs8JoOo"> </param> <embed src="http://www.youtube.com/v/RldyGs8JoOo" type="application/x-shockwave-flash" width="425" height="350"> </embed> </object>

http://www.youtube.com/watch?v=RldyGs8JoOo

http://www.youtube.com/watch?v=mI3xOFnZe5U

http://www.youtube.com/watch?v=iGwhsc5wm6s

http://www.youtube.com/watch?v=GNZW4AOyc_g

http://www.youtube.com/watch?v=heGSzVbE-Mw
Old 07-12-08, 09:31 PM
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Possibly, if you re-read my original post, you would find 2 fixes you could have used and saved you from that gun in your mouth

Scott
Old 07-13-08, 08:07 PM
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Originally Posted by Scott1982
Possibly, if you re-read my original post, you would find 2 fixes you could have used and saved you from that gun in your mouth

Scott
Yours was one of the first I tried. No clamp though and I could figure a way to keep it from popin out. Then you throw in some general exhaustion. It wasn't till the 2nd time around that i saw a roll of electrical tape.......

But, thank you cause it was your idea that got me halfway there.

And there are times when I wish I could see these shortcuts first hand so I took a break and made some vids for the next guy.

I think there is a wide manufaturing tolerance because i put the old one back on and it bled fine. Of course it leaked past the piton after a while but....

I do wish i could see your "cut in half bolt" modification.
Old 07-13-08, 08:41 PM
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Originally Posted by phalerider
Yours was one of the first I tried. No clamp though and I could figure a way to keep it from popin out. Then you throw in some general exhaustion. It wasn't till the 2nd time around that i saw a roll of electrical tape.......

But, thank you cause it was your idea that got me halfway there.

And there are times when I wish I could see these shortcuts first hand so I took a break and made some vids for the next guy.

I think there is a wide manufaturing tolerance because i put the old one back on and it bled fine. Of course it leaked past the piton after a while but....

I do wish i could see your "cut in half bolt" modification.
I didn't take pictures - but it is a simple as taking a hacksaw to a bolt vertically if you will, then spreading the two halves so that they the threaded area goes up a .5mm or so. I couldn't fit my tap in there or I would have done that (and will when I change my clutch). I left a metal shim in there to keep the bolt thread area spread appropriately under pressure. The threaded part of the bolt I cut up such that the whole area being split was contained in the threaded area in the bell housing.

Good luck,
Scott
Old 07-13-08, 09:10 PM
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i really don't remember having this much trouble at all... the pedal would go to the floor as soon as you touched it so i would step on it, make it go to the floor get out and open the bleed valve, until the air stopped flowing and i saw a drop of fluid, repeated this procedure until the pedal wouldn't sink so easily anymore then i would pump it until it was extremely stiff, then open up the bleed valve again until it started spraying fluid, then mom came out and i just had her do the pumping and on the last one i would have her hold her foot strongly pressed up against the clutch so that it would go down as soon as i opened the bleed valve to make sure i got all the air out, did this about 10 times and voila!

the key to it, is just to make sure that you keep constant pressure on the pedal so that when you open the bleed valve the pedal drops (yes you'll have to lift it back up after every try) but when the pedal drops it pushes all the air out. makes it a lot easier w/out having to have any special tools...if you don't have a helper, find a brick or something to put up against the pedal once you pump it and get it really stiff


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