Brakes won’t bleed 62’ split window bus single cab

[UncleBuck66]

Hi everyone,

I’m new to this forum and new to Volkswagens. I inherited a 1962 split window single cab bus and I’m in the process of going though and fixing all of its ailments. The brakes have been kicking my ass for the past couple months and so here I am.

The problem I’m having is this: I replaced the master cylinder when I first got it and all was well, I never put in fluid in because I wasn’t ready to bleed it yet. I struggled with putting on the brake pedal return spring on for a few weeks. (Don’t ask me why I just could not get that sucker on there ) after getting the spring on I wanted to bleed it finally. I put fluid in and started pumping away, keeping the reservoir full at all times. I’m using a vacuum bleeder, the cheap little guns you can get at the auto parts store because I’m a one man army. I started on the passenger rear wheel and I got a couple dribbles to come through the line after about an hour and not much more after that. Then I noticed the master cylinder leaking. I bought a new master cylinder and just replaced it and I’m in the same situation essentially. I’m not exactly sure if it’s leaking from the reservoir and leaking down or leaking from the rubber boot. I’m thinking I keep running the master cylinders somehow and there’s air getting in the system. Or the soft rubber brake lines (I believe that’s what they are called, sorry for my lack of knowledge) have collapsed allowing very small amounts of fluid though. I figured I should diagnose the leaking master before anything first. I’m not sure what I’m doing wrong. Any help would be greatly appreciated.

If you need more details or pictures I’m happy to provide them
Thanks

[timjames722]

Might want to try and bench bleed the master cylinder before installing. Where is it leaking from? I believe if you over fill they will leak from the cap, happened to me when I had it filled to the top. Might not hurt to try and bleed them with someone, just my 2 cents. Hope it works out for you.

You did mention the soft lines, did you replace them?
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[Eric&Barb]

Vacuum bleeders tend to suck air into the brake system due to the cylinder seals are designed to keep pressure in, not out.

Single circuit or dual circuit master cylinder?? Each needs different brake bleeding procedures.

If you do not know that the flex brake lines are less than ten years old, then replace them.
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[UncleBuck66]

I bench bled the new the master that I just put on. As long I have the fundamentals of bench bleeding right? I filled up the reservoir and pushed the piston until fluid came out of the three holes where the brake lines would go. I then installed it.

I’m not exactly sure where it’s leaking from, I’ll try to snap a picture to give you a better idea.

My apologies for not knowing but I don’t know if I have a single or dual circuit if I had to guess it would be single. Any way to tell and I can get back to you?

I was planning on replacing the lines and I was on the fence about it, I didn’t know if I should address the leaking master first. So no, I have not replaced them yet.

I’ll see if I can wrangle up somebody to come give me a hand and try it that way, who knows it might just work then? Haha.

Thank you for your information, much appreciated.

[Eric&Barb]

Go up to the very top of the split bus forum to the stickies and the very top one of those is the "Split Bus FAQ and How Tos - *Read before posting*". Left click on that link and scroll down to the different links till you find the ones about brakes. That sticky has the best of the best of threads on all sorts of subjects, and should be the very first place you should delve into not only when you have a question, but also to read up and find out stuff you would never know you had a question about.

The next place to find answers to questions is the search feature. If you find a thread on same subject, but does not answer your exact question, do feel free to post on that older thread. That way anyone who has posted on that thread will get a notice about your question. This helps to keep down threads on the same question posted over and over.

Then if still no luck, post a new thread with your question.

Single circuit master cylinder had a reservoir with only one chamber. Dual circuit has a two chamber reservoir and thusly connects to two places on the top of the reservoir. Dual circuit is MUCH SAFER, and you should switch to one ASAP.
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[UncleBuck66]

I checked that out before I made this post. I couldn’t seem to find anything for my exact situation, but I very well could have missed it. I will look again and lot more thoroughly to find some answers. I understand that having people posting the same question over and over again can be quite frustrating so my apologies. Thanks again for all the help

Turns out I was correct, I do have a single circuit master cylinder.

[Split 66']

I had the same problem for a while when installing a new dual-circuit master cylinder. My problem ended up being the short brake line that connects the two wheel cylinders on the passenger side front drum. If there is any air leak in the system, anywhere, you'll never get a solid pedal, especially with a single circuit master cylinder.

Try going back over every fitting and connection, to make certain they're all tight. You must have a leak somewhere.
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[ted698]

Do you have the 1mm play on your pushrod?
If not it will not refill the master cylinder properly on its return pedal stroke.
Quick check is grab the pushrod going into the M/C - can you clack it back and forwards everso slightly?

[UncleBuck66]

Yes, I do have play in the pushrod. When I push the brake pedal I can see bubbles coming up. Which I’m assuming is brake fluid going into the master.

I did however notice that the rubber boot just ripped :/ huge bummer. Do I have that on wrong somehow? Is that easily replaceable?

I still have yet to check every one of my connections, but the only leaks I saw on the ground were from the master cylinder.

[Clara]

I've been able to bleed the front by myself under the bus.
If the bus has been sitting, replace the soft rubber lines. the MC lasts better than the rubber hoses.
are you sure the MC is leaking? that it wasn't spill?

What reservoir are you using? I'd found the old original ATE ones are better than the new aftermarket reservoir. new one was junk cracked and leaked on install.
This bus I used the old aluminium reservoir.
On the old plastic ones, I wipe it clean inside with rubbing alcohol and a clean rag.. I want CLEAN fluid in there.
the boot is a dust cover.

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[UncleBuck66]

I agree with you, I think replacing the rubber hoses is the next logical step. Any tricks I need to know with replacing those? I assume it’s pretty straight forward. Take off old one, put on new one? I believe I have a line wrench that I can use on them.

I am positive the Master was leaking, it was coming from the reservoir though. I am using the plastic reservoir that I ordered with the new master. Seems like cheap plastic. I definitely want to try maybe getting a new reservoir. Where did you find yours? I have the reservoir that came off the old reservoir. I cannot confirm if it it’s original or not, at least with the knowledge I have now.

Thank you very much for the information

[Eric&Barb]

Put a little anti-seize on the male brake line threads to keep them from rusting up. Each of the little nuts on the ends of the metal brake lines should be worked away from the end of the lines. Then apply a little anti-seize onto the metal line where those nuts reside, that will help greatly to keep those parts from rusting together.

If the metal brake lines are rusted to the nuts and end up shearing the lines off, just bite the bullet and get a stainless steel brake line kit and never have that problem.

Curl the front flex brake lines slightly to keep them from rubbing the tires.
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[Teeroy]

If your new to VWs, buy a manual, correct year Bentley preferably. Always replace the 4 soft lines if age is unknown. You will probably end up changing or rebuilding the wheel cylinders before your done.
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