Leaking master cylinder

[Bigdougal]

Having replaced my entire brake system I went to fill and bleed the system only to find that I have brake fluid pouring out of the master cylinder where the pipe exits the cylinder, it is pouring out especially when the pedal is depressed. The nut securing the pipe was certainly tight, it isn't cross threaded and the pipe appears to be seated correctly. I am wondering if there is a flaw,in the master cylinder which is a new (VW type I think) from Dale.

I was always paranoid about getting problems where the fluid enters the master cylinder but that is fine.

Any ideas, is there anything I have potentially done incorrectly?

cheers

[heinkeljb]

Doug,

We need to know where the fluid is actually coming out before we can offer an effective solution. The pipe comes from the outside, in through a hole, up in between the "saddle".

The pipe goes through a "T" shaped nut, the pipe is then swagged trapping the nut on the pipe.

Pipe goes into master cylinder, nut slides down pipe, starts on the threads. Before the nut gets to the bottom of the threads in the master cylinder it should lock the pipe up nice and tight.

If your leak is between the threads of the nut and the threads of the master cylinder, If your leak is between the pipe and nut then either the swaged on your pipe is damaged, or the end of the hole in the master cylinder is damaged / has dirt stopping it doing up correctly.
You might be able get away with putting something like Tefflon tape or thread lock (medium or low strength - in case you want to undo this joint again), round the end of the pipe between the swaged end and the nut

Now both of the above scenarios have the same root cause, the swagged end of the pipe is not begin pressed by the nut against the end of the hole in the master cylinder.

Hope this helps

John

[Goatwerks]

You must first install the brass fitting for the pipe before fitting the pipe.
57-63 beetle or Karman Ghia is same length and bore, carefull not to crack the brake line.

[Bigdougal]

Thanks Jim,

You may well have identified my error. I am using a new set of pipes from Robert P in Austria and I have screwed the pipe fitting(nut)'directly into,the bottom of the cylinder. I have just looked at page 7. 10/0 in the parts book and it identifies 2 parts which appear to be fitted to the exit on the master cylinder. Firstly there is item 12 which is part number 9004204 which is listed as a joint ring and item 13 which unfortunately is not identified and has no part number. Is that the brass fitting you are referring to, if so does it have a part number?

Hopefully my screwing the nut and swaged pipe directly into,the cylinder is the problem.

[Goatwerks]

The fitting was on the old master cylinder,1/8 pipe thread to 1/8 brake pipe.

[heinkeljb]

Doug,

I have an old master cylinder which I will take a photo of and post later today for you. If I remember correctly, the hole in the end is quite deep, much deeper that any of the ports on the side. If you look in the ports on the side, you will see the conical surface the swaged end of the pipe pushes up against. The hole in the end maybe to deep for your pipe to reach the end.

John

[Bigdougal]

Jim and John, I have found the brass fitting in question still fitted to the bottom of the old master cylinder.

Firstly, how on earth I forgot to take it off and fit to the new MS is beyond me and secondly it is the only part of the old system that I hadn't thrown out. Good omen, could be a good day!

Thanks again

[heinkeljb]

Well done Doug,

You might get brakes working at this rate before MAY, then you can bring it along to the Dutch Treffen!

John