Tracking Down Brake M/C leak

[KRL]

I've noticed my Brake m/C is leaking in two places:

 

1. From the cap under heavy breaking and cornering.

 

2. Small leak from where the rear brake pipe connects to the M/C. Picture here.

 

For #1 I understand I can fit this race cap. My question is does this fit the standard AP Master Cylinder as fitted to my 2008 Sigma?

 

For #2 - what could the problem be? I've tried tightening up the nut a little and after going out on a blat and trying some heavy breaking the leak appeared again as per the pic.

 

Thanks in advance

[virden]

Re: 2 The first signs of corrosion/ failure of the pipe?

[ChrisC]

I agree, I can't see how the flare can leak like that, unless the pipe end is damaged in some way or the pipe is cracking. I suppose it would be possible to try re flaring the pipe, but a replacement would be my first choice solution.

 

Chris.

[colindavies56]

yes,that cap does fit the standard m/c,

i was given one when my 2010 sigma had its 1st medical.

[colindavies56]

forgot to add,it will not pass the mot with this cap.

something about no light on dash.

[KRL]

Ok thanks.

 

I'll get a new m/c race cap ordered.

 

Replacing the rear break line looks like quite a big job! Lots of things in the way like the gearbox, prop shaft and diff. Anybody have any tips for this job?

[Mark Durrant]

Replacing the rear brake pipe will be very difficult with the engine and gearbox still in the car. I would start by examing the existing flare on the end of the pipe and if possible use a tool to reflare to see if this fixes the leak. If this does not work an easier solution would be to make up a short replacement length of pipe and connect this to the existing brake line within the engine bay.

[TomB]

It is possible to replace the brake lines with the assembled - but it is difficult and not the work of an afternoon. I had the seats out, the tunnel off and the rear tunnel opening off, car on stands, rear wheels off. If you've not done it before, its a tricky awkward job, even if the actual pipe is just two small connections!

 

I replace the pipes over the winter, and the rear took three attempts to get right. Fortunately brake pipe is cheap, but good flaring tools are not. I removed the old pipe, measured it and then order the length ready flared with fittings from Redline. The main difficulty was shaping around the pedal box within over bending, kinking or missing the port on the BMC. A bugger of a job I wish I hadn't started when half way through - at least now its done and I wont have to revisit it for another 15 years.

 

You might be able to just reflare the leaking end, but to do so will loose at least a couple of cms of the pipe length, assuming you get it right first time. If it takes a couple of attempts with a hand hand tool (which arn't great in my experience) which your reduced length pipe is likely to cause difficulties.

 

I have chat with a small local garage or someone like the 7 workshop who with more experience of pipe pipe tools might be more likely to get it flared correctly first time.

[KRL]

Thanks for the replies and information, it is much appreciated.

 

This job looks like it could be quite a can of worms

 

Judging on TomB's experience I am inclined to attempt a re-flare of the pipe or perhaps use an in-line joint with some new pipe as Mark suggests.

[KRL]

Update:

 

After fitting the AP Race cap the problem has totally disappeared

 

I think the standard cap must have been leaking brake fluid onto the rear brake pipe. Then the brake fluid was running down the pipe and gathering at the joint making it appear as if the joint was leaking.

 

Will only change back to the standard cap now when it is MOT time.

[Roger Ford]

I think the standard cap is only needed for SVA/IVA, not MOT. Check the MOT manual. I've not had one on mine for the last six MOTs.