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-   -   slave cylinder bleeding how to help.. please (http://forums.pelicanparts.com/porsche-911-technical-forum/425839-slave-cylinder-bleeding-how-help-please.html)

rcaradimos 08-18-2008 06:34 PM

slave cylinder bleeding how to help.. please
 
Not sure why I can't get the clutch pedal to come off the floor.

1. Should pedal be on floor or up while using power bleeder?
2. Do I have to bleed master clutch cylinder and slave separately?

What I'm doing is filling reservoir, hooking up motive power bleeder and pumping up some pressure (15 psi ) with over flow line pinched closed not to lose fluid from reservoir.
Going under car and opening bleeder on slave some air some fluid closing bleeder valve. Check clutch pedal nothing...

Drivers rear is up on a jack stand..with wheel off
Thanks in advance

wastintime 08-18-2008 08:48 PM

Bob,

NO! the clutch pedal should not be on the floor! You may need to pull it up and depress it serveral times, but while you a bleeding it the pedal should not fall to the floor. Sometimes while bleeding you can inadvertantly depress the pedal and vacuum air back into the system...

Also, that 7mm bleeder screw is very hard to get to. Make sure you have closed and tightened it properly...

I doubt you have any real problems though, lol, I've seen tons of cars where you'd bleed the slave cylinder just for maintenance purposes and the pedal randomly decided to be stubborn.

Best of luck

btw, where in cape cod are you? I was just in Chatham.

Dixie 08-19-2008 03:31 AM

I've always bleed mine at the slave, the old fashioned way.

Hydraulic pressure makes the clutch pedal rise is hydraulic pressure. I suspect you simply don't have enough pressure built up to take up all the "slack" in the system. Try working the pedal by hand four or five times. See if that builds enough residual pressure to make the pedal work.

rcaradimos 08-19-2008 04:55 AM

Just south of the Bourne Bridge

So its a two person job? One to push on clutch pedal and as it's being depressed second person opens bleeder and closes bleeder before pedal is released? This should build pressure up on pedal.

Pushing the pedal by hand I feel just some slight pressure at a inch from bottoming out.. I should have someone hold down the pedal and then open the bleeder releasing any air fluid in the system then closing the bleeder before the pedal is released, repeating this procedure several times?

deep_uv 08-19-2008 05:27 AM

Quote:

Originally Posted by rcaradimos (Post 4127823)
Just south of the Bourne Bridge

So its a two person job? One to push on clutch pedal and as it's being depressed second person opens bleeder and closes bleeder before pedal is released? This should build pressure up on pedal.

Pushing the pedal by hand I feel just some slight pressure at a inch from bottoming out.. I should have someone hold down the pedal and then open the bleeder releasing any air fluid in the system then closing the bleeder before the pedal is released, repeating this procedure several times?

No, you shouldn't touch the clutch pedal while bleeding. You just need to bleed the crap out of it. The pedal should be all the way up while bleeding and never depress it while bleeding. Once you have air in there, it takes a lot of bleeding to get it out.

MatthewBrum 08-19-2008 07:24 AM

Is it possible to un-bolt the slave cylinder from the bell housing and cycle the slave cylinder by hand. I had a 928 with a hydraulic cluth and had a hard time bleeding the air. I got a tip online about disconnecting the slave cylinder and pushing in the rod by hand in and out.

I could instantly hear the air coming out of the master cylinder. After a couple of cycles I bolted it back up and it was perfect. On the 928 the slave cylinder is connected by a rubber hose and made it really easy to use this method.

wastintime 08-19-2008 08:11 AM

the slave cylinder is not coming off without removing the transmission on a 911.

Like most of us have said, you'll probably need to pump the pedal a few times to build up pressure, and then just let a lot of fluid run through it. You should be fine.

rcaradimos 08-19-2008 09:10 AM

Quote:

Originally Posted by deep_uv (Post 4127868)
No, you shouldn't touch the clutch pedal while bleeding. You just need to bleed the crap out of it. The pedal should be all the way up while bleeding and never depress it while bleeding. Once you have air in there, it takes a lot of bleeding to get it out.

How much fluid would I need to run through the system to get the air out?

Some conflicting information here...

Can and should all the bleeding be done at the slave?

wastintime 08-19-2008 09:44 AM

if you haven't touched the master, then the slave should be fine.

Not really conflicting information. When you bleed the slave, you should not depress the clutch and allow it to come down. For whatever reason that happened, now you probably need to pump it several times, probably reaching and physically pulling it back up. Normally, however, you simply don't touch the pedal when you bleed it.

I wouldn't think it could possibly take more than a liter of fluid.

deep_uv 08-19-2008 03:10 PM

Quote:

Originally Posted by wastintime (Post 4128279)
if you haven't touched the master, then the slave should be fine.

Not really conflicting information. When you bleed the slave, you should not depress the clutch and allow it to come down. For whatever reason that happened, now you probably need to pump it several times, probably reaching and physically pulling it back up. Normally, however, you simply don't touch the pedal when you bleed it.

I wouldn't think it could possibly take more than a liter of fluid.

I've introduced air in my clutch line by running the level too low during bleeding. When that happened the clutch threw itself to the floor and stayed there when I initially pressed it after the bleed. I had to pull it back up by hand. It took just a little less than a liter as you say to get all the air out. I went ahead and used the whole liter anyway just to be sure

I couldn't pump, it would just body slam itself to the floor. Bleeding will take care of the air. Just get the clutch to stand up by hand and bleed. You're right, you definitely don't want to pump the clutch pedal while bleeding. I think we're pretty much in agreement, it's just in the details. :)

rcaradimos 08-19-2008 03:36 PM

Do you guys have the Bentley Service Manual?
Page 301-10

rcaradimos 08-19-2008 03:42 PM

The manual states: 1. bleed until no air in system with power bleeder 2. with air bleed screw open slowly depress clutch pedal fully several times 3. with pedal fully depressed close bleeder screw 4. remove pressure bleeder top of fluid

Dixie 08-19-2008 03:47 PM

Quote:

the slave cylinder is not coming off without removing the transmission on a 911.
I've removed the one on my 911 without dropping the motor or trans...

But back to Bob-in-Cape-Cod's issue. Have you tried simply pumping the pedal a few times?

burgermeister 08-19-2008 03:56 PM

Remember the front of the car needs to be higher than the rear to bleed the slave cylinder - bleeder screw needs to be at the high spot.

Also, if you got lazy like me and just jacked up one side of the car, the reservoir nipple that feeds the clutch master cylinder is now in a spot with very little (if any) brake fluid (if you use the pressure bleeder dry).

I did not learn the above by introspection like one might presume, but instead by doing the wrong thing and suffering the consequences... goes to show, sometimes it's best to walk away before one does silly things. It usually saves time. Now I just need to follow my own advice.

Once I corrected both of these things, mine bled just fine.

rcaradimos 08-19-2008 04:01 PM

Yes Capt.
No pressure building up.. @ 51 I felt my age laying on the concrete for 3 hours last night, looking for answers in the easy chair before I dive under the trany again to get all greasy for the second time. The first hour was to remove the slave, the next hour was cleaning inspection and reinstalling the slave (by the way removing the little bracket that holds the line was a must for me to get a wrench on the fluid line). 3rd hour was tying to get the pedal back.

rcaradimos 08-19-2008 04:28 PM

Quote:

Originally Posted by burgermeister (Post 4129046)
Remember the front of the car needs to be higher than the rear to bleed the slave cylinder - bleeder screw needs to be at the high spot.

Also, if you got lazy like me and just jacked up one side of the car, the reservoir nipple that feeds the clutch master cylinder is now in a spot with very little (if any) brake fluid (if you use the pressure bleeder dry).

I did not learn the above by introspection like one might presume, but instead by doing the wrong thing and suffering the consequences... goes to show, sometimes it's best to walk away before one does silly things. It usually saves time. Now I just need to follow my own advice.

Once I corrected both of these things, mine bled just fine.

I have one corner up and used the power bleeder dry.. hence the air in the line.
Will fluid in the power bleeder do the trick or is it a must to get the front of the car up

Dixie 08-19-2008 04:51 PM

Let's start at the beginning. What precipitated the need to bleed the line? What did you replace and why?


While I await your response, I suggest you try gravity-bleeding the line. Simply open the bleed screw on the slave, with the clutch pedal up. Just let the fluid flow until the air is out. No pressure devices or assistance needed. When you think the air is out, close the bleed screw, pump the pedal a time or two, and you should be good. It shouldn't take more than ten minutes.

A few helpful tips: Use a length of clear tubing over the bleed screw. You can see the air bubbles, and it keep the mess down. Don't worry about tipping the car. If fluid is coming out the slave, the slave is lower than the reservoir.

Report back. Especially regarding how this problem started.

rcaradimos 08-19-2008 05:38 PM

Two weeks ago Sat. I had some fun at a AutoX event, on one run I went into a spin and put both feet in. I think that's what started the problem... last Sat. running with a group for our monthly run I noticed that my clutch pedal seemed soft at the top 2/3" and my reservoir was lower then normal. Added some fluid (pedal felt better) I put a piece of cardboard under the engine / transmission area; the next morning I checked and had some leaking from the area.
I decided to remove the slave after looking though the inspection opening and seeing the push rod looked wet from fluid. Since I had no problems rebuilding my break calipers 2 years ago I felt that opening up the slave would be worth the effort all of 2 minutes. Cleaned some gunk out of cylinder and around the seal reassembled and reinstalled to test for any leaks. My intention is to replace the slave if loss of fluid appears after getting my pedal back. I guess you can look at this as the practice run on replacing the slave in the near future.
Thanks for your help

rcaradimos 08-19-2008 05:55 PM

http://forums.pelicanparts.com/uploa...1219197147.jpg
http://forums.pelicanparts.com/uploa...1219197175.jpg
http://forums.pelicanparts.com/uploa...1219197215.jpg


More pics from thhe fun run:
http://restlessnative.smugmug.com/gallery/5726544_obzUh#353518348_9TMAx

deep_uv 08-19-2008 06:20 PM

If you did a dry bleed you likely made the most common mistake of running the fluid too low in the reservoir. The pickup for the clutch circuit is mid height in the reservoir as opposed to the brake circuit which is in the bottom. Once the fluid level gets to midway down in the reservoir, you're introducing air into the clutch line. Use the "wet method" and fill your pressure bleeder with at least a liter of fluid and run it through. If it's still blowing bubbles after that, add another liter and try again. That will fix you up. The car tilting thing makes no sense to me. You don't do that when you bleed the brakes, right? This is no different. Just pump fluid through it until you have no more bubbles and don't let the reservoir go below half full in the process.

Regards,


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