'71 Bus with a serious brake fluid habit

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JLT
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'71 Bus with a serious brake fluid habit

Post by JLT » Mon Apr 26, 2010 1:01 pm

This spring, I had the brake fluid in my '71 bus flushed out and replaced with new stuff (I figured that the PO had never had this done in his 30+ years of owning the car, and it was time).

Lately, my bus has a serious jones for brake fluid, like six ounces (half a bottle) every hundred miles or so. I've looked at all the places where you'd expect to see brake fluid leakage, short of actually taking the wheels off and eyeballing the cylinders directly, but there's no sign that the stuff is leaking out there. Likewise with the master cylinder, which is dirty but dry. No drips under the bus. It seems to me that with that amount of brake fluid being used up, any leakages there should be glaringly obvious.

Somebody told me that it sounds like the seal between the master cylinder and the brake booster ruptured and that the fluid is getting sucked into the booster and, ultimately, the engine itself, which is why there's no evidence of leakage anywhere. Is this likely, or even possible? And, if so, does it mean that the booster as well as the master cylinder needs rebuilding?

And could the brake fluid flush and replacement have somehow caused or aggravated this problem?

FWIW, once the brake fluid reservoir is topped up, the brakes work fine.
-- JLT
Sacramento CA

Present bus: '71 Dormobile Westie "George"
(sometimes towing a '65 Allstate single-wheel trailer)
Former buses: '61 17-window Deluxe "Pink Bus"
'70 Frankenwestie "Blunder Bus"
'71 Frankenwestie "Thunder Bus"

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vdubzen
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Post by vdubzen » Mon Apr 26, 2010 1:07 pm

had something similar with my super. replaced the master cylinder and the gulping has stopped.
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Runamuck Bus
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Post by Runamuck Bus » Mon Apr 26, 2010 1:30 pm

I recently had a brake booster rebuilt by 'that Texas guy'. He did a good job and also told me to replace my master cylinder because he found brake fluid in the booster.
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Randy in Maine
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Post by Randy in Maine » Mon Apr 26, 2010 5:57 pm

Runamuck Bus wrote:I recently had a brake booster rebuilt by 'that Texas guy'. He did a good job and also told me to replace my master cylinder because he found brake fluid in the booster.
That is what JLT needs to do also.
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JLT
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Post by JLT » Wed Apr 28, 2010 8:52 am

Randy in Maine wrote:
Runamuck Bus wrote:I recently had a brake booster rebuilt by 'that Texas guy'. He did a good job and also told me to replace my master cylinder because he found brake fluid in the booster.
That is what JLT needs to do also.
And that's what I'll do. I've read the threads elsewhere on this site about recommendations for parts. From what I can glean from the Bentley, it doesn't look too hard to replace the master cylinder.

I would be interested in whether I should assume that the booster is bad as well. From what I've heard, it may well be fine once the brake fluid has been drained from it (or what's left of it after the remainder has been sucked into the engine).

I still haven't heard about whether the springtime flush-and-fill might have been part of the problem, but it's sort of academic anyway. Still, it would be good to know, for people who might have this procedure done in the future.
-- JLT
Sacramento CA

Present bus: '71 Dormobile Westie "George"
(sometimes towing a '65 Allstate single-wheel trailer)
Former buses: '61 17-window Deluxe "Pink Bus"
'70 Frankenwestie "Blunder Bus"
'71 Frankenwestie "Thunder Bus"

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Post by Amskeptic » Fri Apr 30, 2010 8:46 am

JLT wrote:I still haven't heard about whether the springtime flush-and-fill might have been part of the problem, but it's sort of academic anyway. Still, it would be good to know, for people who might have this procedure done in the future.
Sometimes your car responds to a flush by bleeding to death because the new fluid doesn't get along with your old seals.

Carefully and thoroughly vacuum out your booster, a 12mm vacuum hose taped to a shop-vac hose should do it.
BobD - 1978 Bus . . . . . . . . . . .111,130 miles
Chloe - 1970 bus . . . . . . . . . . . 206,787 miles
Naranja - 1977 Westfalia . . . . . 81,366 miles
Pluck - 1973 Squareback . . . . . 55,510 miles
Alexus - 1991 Lexus LS400 . . . 72,113 miles

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Post by Gypsie » Fri Apr 30, 2010 10:51 am

I'm curious, would the brake fluid that may be getting sucked down the brake booster vacuum line damage the line or the backcheck valve if it sits in there? If so would it be advisable to flush out this system to clear any residual fluid?
So it all started when I wanted to get better gas mileage....

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Post by JLT » Mon May 03, 2010 4:57 pm

Amskeptic wrote: Sometimes your car responds to a flush by bleeding to death because the new fluid doesn't get along with your old seals.

Carefully and thoroughly vacuum out your booster, a 12mm vacuum hose taped to a shop-vac hose should do it.
Thanks, Colin. That's what I needed to know. I'll suck as much of it up as I can, and we'll see what happens. As Gypsie pointed out, the back check valve might need monitoring, as well. (On the other hand, the brake fluid might have been giving it a nice shot of lube ....)
-- JLT
Sacramento CA

Present bus: '71 Dormobile Westie "George"
(sometimes towing a '65 Allstate single-wheel trailer)
Former buses: '61 17-window Deluxe "Pink Bus"
'70 Frankenwestie "Blunder Bus"
'71 Frankenwestie "Thunder Bus"

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Another question, this time about '71 brake fluid reservoirs

Post by JLT » Thu May 06, 2010 1:12 pm

Sorry to keep pestering you guys, but the master cylinder story has taken a new twist. I'll leave it to our adminstrators to decide whether to keep this message on the existing thread or have it start a new one.

Since I needed a new master cylinder, I ordered one from Wolfsburg West. The write-up for my model of master cylinder, for the '71 bus with the brake booster, said that the original reservoir wouldn't fit on to it, and that I'd have to order the reservoir for the later bus. (BTW, one of the other suppliers -- Bus Depot maybe? -- said the same thing on their web site, and I figured that they had the same source.) So I ordered both the master cylinder and the reservoir.

When I got the new reservoir out of the box and held it next to the original, I could see right away that I had a problem --- the inlet tube was at right angles to the original. So the fill tube wouldn't stretch far enough to fit. I called Wolfsburg West and explained the problem, and they basically said it was my problem, not theirs. That wasn't the answer I wanted to hear, so they referred me to the SAMBA, where I found that the hose was basically unavailable new, and that most plastic/vinyl/neoprene hose material wouldn't stand up to brake fluid. More news I didn't want to hear.

So I took out the old master cylinder, pried the reservoir off, and laid the old and new master cylinders out side by side. Surprise: I could see no reason at all why the old reservoir wouldn't sit on the new master cylinder. The distances between the to inlets were identical, and the outlets on the reservoir itself were identical, both in size and shape.

The upshot is that I've decided to use my old reservoir (using new seals, of course). But the question remains: why did Wolfsburg West think that the old reservoir wouldn't fit? Is there a possibility that my MC and reservoir was itself a retrofit?
-- JLT
Sacramento CA

Present bus: '71 Dormobile Westie "George"
(sometimes towing a '65 Allstate single-wheel trailer)
Former buses: '61 17-window Deluxe "Pink Bus"
'70 Frankenwestie "Blunder Bus"
'71 Frankenwestie "Thunder Bus"

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Post by hambone » Thu May 06, 2010 1:22 pm

In my experience, WW is an awesome vendor with high quality and accurate parts. But no one is perfect.
Usually they will do a refund if something isn't right. Not sure what is up. I'd call them again and ask for the owner.
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Re: Another question, this time about '71 brake fluid reserv

Post by Amskeptic » Thu May 06, 2010 8:16 pm

JLT wrote:Sorry to keep pestering you guys, I've decided to use my old reservoir (using new seals, of course). But the question remains: why did Wolfsburg West think that the old reservoir wouldn't fit? Is there a possibility that my MC and reservoir was itself a retrofit?
VW was jerking around with lots of different configurations for reservoirs, locations thereof, master cylinders. The blue upper reservoir-to-lower reservoir inlet hose I am pretty sure is available at Pelican Parts is it?

So your inlet nipple of the lower reservoir was oriented 90* from the replacement reservoir? Make two notes:
a) good thing that your old one was not cracked or nasty.
b) you CAN use the new one if yours does go bad, just get McGyver on it.
Colin
(I use my old parts where possible anyways)
BobD - 1978 Bus . . . . . . . . . . .111,130 miles
Chloe - 1970 bus . . . . . . . . . . . 206,787 miles
Naranja - 1977 Westfalia . . . . . 81,366 miles
Pluck - 1973 Squareback . . . . . 55,510 miles
Alexus - 1991 Lexus LS400 . . . 72,113 miles

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JLT
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The end of the story (I hope)

Post by JLT » Thu May 13, 2010 4:13 pm

Here's the story as of today:

As I said, I installed the new master cylinder using the old reservoir. I then proceeded to bleed the brakes to get rid of the air in the system. The front brakes bled beautifully, but the back ones didn't .... no pedal going to the floor, no significant amount of air or brake fluid coming out of the bleeder valve (just a measly bit somewhere between an ooze and a dribble). At this point, I gave up and decided that I was in over my head.

I took the bus to Kombi Haus, and they said that the rear brake lines were fairly well plugged up, and that the flexible parts needed to be replaced. (Justin also said that there were no issues with either the master cylinder or my installation job ... just the lines between the master and slave cylinders.

The total bad news: two brake hoses (left and right rear) at about 17 bucks apiece, two hours of labor ... a total of about $220, not including the $150 I paid for the master cylinder itself. I'm returning the unused reservoir and seals to WW for a refund, and I'm sure they'll treat me right. (Note to others: I ordered the seals for the junction between the MC and the reservoir but didn't need them, since the seals already came installed in the MC.)

I'm taking a long road trip to the coast this weekend, and we'll see if we've licked the problem.
-- JLT
Sacramento CA

Present bus: '71 Dormobile Westie "George"
(sometimes towing a '65 Allstate single-wheel trailer)
Former buses: '61 17-window Deluxe "Pink Bus"
'70 Frankenwestie "Blunder Bus"
'71 Frankenwestie "Thunder Bus"

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