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epowell
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Joined: September 23, 2015
Posts: 4733
Location: Czech (mostly) Vancouver (sometimes)
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 Posted: Tue May 07, 2019 2:33 am Post subject: Clutch master cylinder replacement |
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Hi Folks...
In my quest to solve my rough shifting issue, I finally had the brilliant inspiration to investigate the origin of the tiny puddle of brake fluid I have been observing under my feet near the pedals for about a year now!
Low and behold I discovered a kind of cylinder (what I subsequently learned is my Clutch Master Cylinder > I previously didn't even know such a thing existed - I have always just assumed that the BMC doubled as a CMC! ooops!)
So this thing is slowly leaking.... I guess there is no question that it needs replacing. But I have a few questions:
- The PO said that he recently replaced the slave cyl., but it doesn't look so new and the bleeder was stripped > so I am thinking to play it safe and just replace that also.... good idea? ...or waste of time and money?
- I'm not quite sure how to block off the lines to prevent fluid from entering the system... this article https://campwestfalia.com/vanagon-clutch-master-cylinder-replacement/ suggests using clamps on the rubber lines, but I have heard that this technique is a big NO NO. ...thoughts?
Any other considerations I should look into?
Thanks
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epowell
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Location: Czech (mostly) Vancouver (sometimes)
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| Posted: Tue May 07, 2019 2:54 am Post subject: Re: Clutch master cylinder replacement |
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OK, I just re-read some old emails from the PO who said he replaced the clutch fluid LINE, not the slave... so I will go now and just order both cylinders: master and slave.
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dobryan
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Joined: March 24, 2006
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Location: Brookeville, MD
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epowell
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Joined: September 23, 2015
Posts: 4733
Location: Czech (mostly) Vancouver (sometimes)
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| Posted: Tue May 07, 2019 5:01 am Post subject: Re: Clutch master cylinder replacement |
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| dobryan wrote: |
| Replace both master and slave. Do not worry about closing any fluid lines |
Really? So just open it all up and replace, no need to block any lines? Isn't there a risk of getting air backed up into the reservoir?
Does it matter which I replace first, master or slave?
I have ordered both, and will arrive on Thursday! 
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dobryan
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Joined: March 24, 2006
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Location: Brookeville, MD
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| Posted: Tue May 07, 2019 5:28 am Post subject: Re: Clutch master cylinder replacement |
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| epowell wrote: |
| dobryan wrote: |
| Replace both master and slave. Do not worry about closing any fluid lines |
Really? So just open it all up and replace, no need to block any lines? Isn't there a risk of getting air backed up into the reservoir?
Does it matter which I replace first, master or slave?
I have ordered both, and will arrive on Thursday! |
The reservoir will drain down to the level of the hose on the side that feeds the clutch master cylinder. But only that far. It will not drain low enough to get air into the brake lines. The brake master cylinder is fed from the bottom of the reservoir.
I'd replace the master cylinder first, then bleed the air out, then replace the slave and bleed. BTDT recently...
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Dave O
'87 Westy w/ 2002 Subaru EJ25 and Peloquin TBD
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epowell
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Joined: September 23, 2015
Posts: 4733
Location: Czech (mostly) Vancouver (sometimes)
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| Posted: Tue May 07, 2019 6:29 am Post subject: Re: Clutch master cylinder replacement |
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| dobryan wrote: |
I'd replace the master cylinder first, then bleed the air out, then replace the slave and bleed. |
What is the advantage of bleeding each separately consecutively? Isn't that a waste of time and fluid? ...or?
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epowell
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Location: Czech (mostly) Vancouver (sometimes)
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| Posted: Tue May 07, 2019 7:33 am Post subject: Re: Clutch master cylinder replacement |
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...or maybe I misunderstood - does the clutch master cylinder also have a bleeder... can you bleed that locally or do you have to do it thru the slave cylinder?
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cawvin
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Location: Whatcom County
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| Posted: Tue May 07, 2019 7:41 am Post subject: Re: Clutch master cylinder replacement |
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| epowell wrote: |
Any other considerations I should look into?
Thanks |
When I replaced my clutch master cylinder, I believe I wedged a little rubber stopper in the flex hose that comes down from the reservoir. The hard line that runs to the slave didn't leak too bad. I may have done the ol' cut-corner of a plastic bag with a zip tie around it trick.
It is tricky to access the thing, and the best way I found was actually to pull the driver's seat out of the vehicle, sit backwards in that spot, and lie down with my back on the driver's feet floor with my head resting on the brake pedal.
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Dampcamper
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Location: Rainy Portland, Oregon
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| Posted: Tue May 07, 2019 7:45 am Post subject: Re: Clutch master cylinder replacement |
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You'll be opening the hydraulic system up, don't worry about air in there because you'll need to bleed anyway. You can use either a turkey baster (rubber suction bulb) to draw fluid down below the magic line on the reservoir or you can get a length of 3/16" / 5mm clear vinyl tube (maybe 3 ft / 1m), slip one end over the nipple on the slave cylinder and have the other into a collecting jar and just open the nipple. It will slowly drain out just by gravity. This will reduce the amount of spillage you need to clean up. Wear nitrile rubber gloves when working with brake fluid and promptly wipe up spills, it is unkind to hands, paint, etc.
When you have accomplished the replacement take your half liter of brand-new brake fluid and fill the reservoir, open the slave cylinder nipple (with tube attached) and wait until you get bubble-free fluid dribbling down.
You'll still need to do the traditional bleeding process but this will prime your system. Keep the level in reservoir topped up while you do this.
And if your brake fluid has been in there for a while (5 years?) it might be wise to flush your brake system too. Buy another couple of half-liters of brake fluid for this. (Brake fluid absorbs moisture which can coalesce out inside your slave cylinders, these drops can cause corrosion inside the cylinders leading to leakage).
If the brake fluid in the reservoir is not nice and clear (kind of brown like weak coffee or darker) it may be telling you it is old. |
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shagginwagon83
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Joined: February 07, 2016
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| Posted: Tue May 07, 2019 8:00 am Post subject: Re: Clutch master cylinder replacement |
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i drained my brake fluid by using the drain bleeder on one of the brakes.
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"Jo Ann" - '83.5 Westfalia EJ22e w/Peloquin
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crazyvwvanman
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| Posted: Tue May 07, 2019 8:03 am Post subject: Re: Clutch master cylinder replacement |
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That is what I would be inclined to do, but some at all 4 brake bleeders.
Mark
| shagginwagon83 wrote: |
| i drained my brake fluid by using the drain bleeder on one of the brakes. |
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epowell
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Joined: September 23, 2015
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Location: Czech (mostly) Vancouver (sometimes)
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| Posted: Tue May 07, 2019 8:16 am Post subject: Re: Clutch master cylinder replacement |
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My brake fluid is less than 2 years old and very clean after a total brake system rebuild summer 2017. Never had to put a drop into the reservoir since then.
So 2 years (I was hoping to leave it until 3  ) ...but yes, might as well just bleed the entire system including brakes. I am a bit afraid to touch drain nipples... for fear that will crack off.
Regarding bleeding the clutch master cylinder, I see on this vid at 8:43 the guy just uses the 12mm hydraulic line nut to bleed... hmmm.... pretty messy, and how will you really know all the air is out?
https://www.youtube.com/watch?v=StawBx6oXNA
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Igeo
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| Posted: Tue May 07, 2019 8:42 am Post subject: Re: Clutch master cylinder replacement |
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However you decide to drain the system will work. One important tip would be to aquire a flare nut wrench aka line wrench. Using a standard open end wrench may strip the nut flats.
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dobryan
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Joined: March 24, 2006
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Location: Brookeville, MD
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| Posted: Tue May 07, 2019 8:43 am Post subject: Re: Clutch master cylinder replacement |
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I did the master cylinder bleed at the 12mm banjo bolt first. Then bled at the slave to clear any small amount of air in the line out and flush new fluid in, then remove and replace the slave and bleed just the slave.
If you are afraid of the brake bleeders breaking then I'd leave them alone for this.
I did not remove the drivers seat or go contortionist. I could do it by working from the open drivers door and kneeling on the ground.
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Dave O
'87 Westy w/ 2002 Subaru EJ25 and Peloquin TBD
"To travel hopefully is a better thing than to arrive." Robert Louis Stevenson
MD>Canada>AK>WA>OR>CA>AZ>UT>WY>SD
https://www.thesamba.com/vw/forum/viewtopic.php?t=620646
Building a bus for travel in Europe (euroBus)
https://www.thesamba.com/vw/forum/viewtopic.php?t=695371
The Western Syncro build
https://www.thesamba.com/vw/forum/viewtopic.php?t=746794 |
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epowell
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Joined: September 23, 2015
Posts: 4733
Location: Czech (mostly) Vancouver (sometimes)
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| Posted: Tue May 07, 2019 8:49 am Post subject: Re: Clutch master cylinder replacement |
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this is interesting
Link
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crazyvwvanman
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| Posted: Tue May 07, 2019 8:51 am Post subject: Re: Clutch master cylinder replacement |
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Well, if you really did a "total brake system rebuild summer 2017" why would there be any concern about the newish bleeder nipples now?
Mark
| epowell wrote: |
| My brake fluid is less than 2 years old and very clean after a total brake system rebuild summer 2017.....I am a bit afraid to touch drain nipples... for fear that will crack off.... |
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epowell
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Location: Czech (mostly) Vancouver (sometimes)
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| Posted: Tue May 07, 2019 9:02 am Post subject: Re: Clutch master cylinder replacement |
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Is there only one bleeder... my mind is a bit foggy on this > I thought there were bleeder screws and also separate "drain" screws? ? ?
Yes all of the ordinary BLEEDER screws are fresh and working easily.
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dobryan
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MarkWard
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| Posted: Tue May 07, 2019 9:49 am Post subject: Re: Clutch master cylinder replacement |
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Not sure why you would mess with the brake hydraulics at all replacing the clutch master and slave cylinders. Two completely different systems other than the shared reservoir which someone already stated won't completely empty so that air might get introduced into the brake system. Its a fail safe.
Bleeding the master, there is no bleeder valve. The idea is to work some fluid through the clutch master so that it is not dry. Opening and closing the outlet hose while you pump the pedal is all you need to do. The real work is when you get back to the clutch slave to bleed it.
With the reservoir topped off, open the clutch bleeder and wait for gravity to get the fluid back there and running out. You are now ready to bleed the clutch slave cylinder.
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Ahwahnee
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| Posted: Tue May 07, 2019 11:26 am Post subject: Re: Clutch master cylinder replacement |
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Since it sounds like you'll be replacing the slave, you might consider this:
https://www.thesamba.com/vw/forum/viewtopic.php?t=717571&highlight=
May depend on parts availability where you are but if done at the time of slave replacement it would be a doddle to add a remote line. |
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