Date: Sat, 12 Feb 2005 14:13:52 -0600
Reply-To: John Rodgers <inua@CHARTER.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: John Rodgers <inua@CHARTER.NET>
Subject: Re: The second bleeding: Clutch master/slave failure observation
In-Reply-To: <F29D6897-7D12-11D9-8E65-000A959B3796@knology.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Jim,
When I replaced my clutch master, I refilled the tank, loosened slightly
the fitting on the top of the master, then pressed the clutch petal a
few times until I got fluid running out (catching it up with a rag).
Then I tightened the fitting. Next I topped the tank again, an proceeded
to pump the clutch pedal at least 75 times if not more. At first there
was no pressure, then near the 75 mark it began to pressure then around
75 for so I was able to get full pedal. I have never ever done anything
else to it and that was 30,000 miles or so past.
Somewhere, I have/had read that the manula tranny clutch system will
self-bleed. For me, it appears that such was the case. And I have never
had a problem with it ever. Oh, I do expect slave cylinder trouble
......eventually. It is after all a mechanical device and all mechanical
devices give trouble ...... sooner or later. But after 30,000 miles I
don't think any clutch slave cylinder failure will ever be related to
changing out the clutch master.
My $0.02.
Regards,
John Rodgers
88 GL Driver
Jim Felder wrote:
> I recently replaced my clutch master cylinder on a hunch. Neither
> cylinder was leaking, and I had replaced the slave cylinder just over a
> year ago, so I had to guess and was right.
>
> In reading up on the how-to, I repeatedly ran across this bit of
> conventional wisdom: if the clutch master cylinder fails in a vanagon,
> the slave is often not far behind.
>
> I am writing this to suggest that that may not always be the case.
>
> Here's why: I also ran across a piece of advice that suggested that
> bleeding the vanagon clutch system, which apparently cannot be done
> with the two-person close-up-open-down method, would need to be done
> again in several hundred miles and only with a pressure (per Bentley)
> or vacuum (per almost everyone else) bleeding tool.
>
> I replaced my master cylinder the night before leaving on a recent 2000
> mile trip. The car shifted well for the first thousand miles, balking a
> few times into all gears after than, and really started giving me
> trouble about forty miles from home. It was as if one of the cylinders
> wasn't working again, and since I had just replaced the master, I
> figured it may be the slave that had gone bad, just as vanagon lore
> said it would.
>
> But I remembered the advice about the second bleeding, and I did that.
> Problem fixed.
>
> I wonder if some of the slave cylinder failures reported after master
> cylinder replacement are due to the fact that after master cylinder
> replacement, some time in the next 2000 miles air bubbles are going to
> cause a problem that make the slave cylinder seem inoperative when it
> really isn't. Since master cylinder replacement puts in a big slug of
> air at the front of the system that has to travel to the back, it only
> shows up after so many brake applications. If the slave cylinder is
> replaced to correct the problem, air that enters at the back end of the
> system is now easily bled out, making it seem that the slave cylinder
> replacement was necessary--when in fact it was only the bleeding that
> was necessary.
>
> Just a theory and will maybe save somebody fifty bucks and some trouble.
>
> THE SECOND BLEEDING
>
> Turning and turning the wrong size flare wrench,
> The mechanic cannot reach the rag in time.
> Things fall apart, the repair will not hold.
> The new parts lack cleanliness while the
> floor is filled with brake fluid,
> And everywhere the front upholstery is drowned.
> Surely some revelation is at hand;
> Surely the second bleeding is at hand.
> The second bleeding! No sooner are those words out of my mouth
> Than my mind is trouble by a page out of Bentley.
> ...
> The darkness drops again, but now I know
> That twenty years of dependability were vexed to nightmare
> By a dripping fitting.
> ...
> And what rough beast, its hour come round at last,
> Is slouching toward Wolfsburg to be born?
>
> Apologies to W. B Yeats.
>
> Jim
>
>
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