Hi there, hope someone can help. The brakes on my 67 1500 Beetle have been erratic for a while and recently failed completely. Fortunately I had felt it coming and was able to carefully get home - just!!
As there was no loss of fluid and all the wheels looked dry (no obvious signs of leaking slave cylinders/calipers) I assumed master cylinder failure. I have the single circuit type of master cylinder fitted and purchased a replacement ATE cylinder.
Fitting was relatively straightforward and so I set about bleeding the entire system. All appeared to be going ok until I spotted three things of concern.
Firstly, and rather importantly, there were still no brakes. The pedal went straight to the floor and no amount of pumping would help. Secondly, after pumping the front brakes were binding and would not release (despite there being no pressure on the pedal at all). Thirdly brake fluid was pouring out of the rubber bung that holds the inlet pipe from the reservoir. Clearly there was some sort of pressure build up in the system which led me to believe the push rod from the pedal might be out of adjustment - I understand the length is quite critical to allow the pressure to release as the piston returns to its rest position. I checked the clearance and it seemed OK. To be absolutely certain I backed it off a considerable amount to ensure absolutely no contact between the rod and the piston in the master cylinder.
I then went through the bleeding procedure again and interestingly (but logical I guess) as soon as I unscrewed the first bleed nipple at the rear the pressure in the system was released and the front wheel binding disappeared.
However after going through the whole process again the result is exactly the same. Brake fluid pouring out of the rubber bung, front wheels binding (possibly the rear as well - I didn't check) and brake pedal goes straight to the floor.
Am I missing something obvious? Have I received a faulty master cylinder? This is driving me mad so I'd really appreciate any thoughts you guys might have. I have only been back in the VW fold since last September so its probably 20 years since I last worked on Beetles and I don't remember them ever being this frustrating!!!
Cheers
Batton

Hello and welcome to the forum. 😃
Interesting problem you have there. How old are the flexible brake hoses on your car? old hoses can sometime swell up and the internal diameter of the hose becomes much smaller or closes completely, brake fluid can be forced through the hose but then can't release so the brakes are stuck on. I'm not quite sure why the brake pedal goes straight to the floor though, unless there is still air in the system.
I think you'd be very unlucky to get a faulty new master cylinder, especially an ATE one.

I had real problems bleeding the brakes on my beetle, no amount of pumping seemed to get the air out. In the end I bought a Gunsons EziBleed kit which worked a treat.

Good luck, let us know how you get on.
Cheers,
John

First thing I thought off when I read this was flexi's too!

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Thanks Guys, its nice to get other opinions. The flexible brake pipes all look in pretty reasonable condition from the outside but you never know what is lurking inside.
I also think that the connection from the reservoir to the master cylinder is non standard. All the diagrams I have seen suggest a short push fit connection to a flexible hose. Mine has a rigid copper pipe with a short flexible connection at the reservoir end. I was a little suspicious to see this pipe held in place in the rubber bung of the old master cylinder by a cable tie.
I think with your help I have convinced myself to replace all the flexible hoses including the feed to the master cylinder so many thanks for your responses. I'll let you know how I get on.
Just out of interest since posting I have found Rob and Dave's Aircooled VW pages website. There's a mine of useful information to be found there. Here's the link:

https://www.vw-resource.com/index.html 

There is a frightening amount of info on brakes there too!. Has anyone any views on/experience of externally bleeding the master cylinder? None of the manuals I have even mention it and yet these guys seem to think its imperative to clear all of the air out of the system!

Thanks again

Batton

If only one wheel is binding it is likely to be a flexi hose. You would be extraordinarily unlucky if all four flexi hoses failed simultaneously. So if all four are binding it's more likely the master cylinder. From what you describe, something is stopping the piston from returning. Release a union at the master cylinder and check for pressure there with the pedal released. Is the only thing causing the pedal to return the spring on the pedal? Make sure the pushrod is not at an angle and binding. Dirt in the piston ports can stop fluid returning to the resevoir but, as you've changed the master cylinder, that would be unlikely.

Thanks Kabman.
I think you are right - as both front wheels are binding (I haven't checked the back yet) it would have to be a rather unlucky coincidence for all the flexi hoses to go at once. That said the car was laid up for about 2 years before I bought it so whether that has contributed to the internal deterioration of the hoses I don't know. The rear slave cylinders were all renewed by the previous owner before selling it so there shouldn't be a problem there.
I think I'll take another look at the master cylinder - there must be some sort of pressure build up there to force the reservoir fluid out of the rubber bung in the top of the master cylinder.
If there's nothing obvious there then I'll replace the flexi hoses and see where that gets me.
I'm off to the Nuremburg Toy Fair for 3 days tomorrow so I'll have an enforced break from lying under the car every evening and maybe time to think through a solution. I can't believe how much brake fluid I'm getting through!!
Many thanks for all your contributions - its a great help to share thinking!
Cheers
Batton

Am i right so far,67 1500,front disc brakes?
And you have already replaced the master cylinder.
Was it a disc brake master cylinder?
As they are different,hence VW usually marking them with a stick on blue plastic band.
I experienced this on a type 2 about 15 years ago.
If i have got the story all wrong ignore the rantings of an old man.

I returned from my business trip to Germany on Friday and spent some quality time on the Beetle yesterday, having ordered several parts for delivery whilst I was away. Obviously the break did me good and I went about the work with renewed vigour.
The result is that I now have brakes again!!
I'm not sure exactly what it was but I basically renewed all the low pessure feed to the master cylinder, removed and then re-installed the new master cylinder, replaced the flexible hoses at the front, put in new bleed nipples whilst I was about it, adjusted the piston into the master cylinder and then bled the whole system - again. Then 'Hey Presto' - brakes!!!
Thanks to everyone for their comments and suggestions - it really helps to have other people's thinking to consider when you have hit a brick wall. I hope I will be able to reciprocate some time when someone else has a problem.
Cheers
Batton