Brake Master Cylinder Leak - How hard to change?

[Chris Berry]

It seems that a seal is leaking on my Master Cylinder, the reason why I believe its a seal is that it only leaks during hot weather!!

On most days, there’s no sign of a leak but once the really hot weather starts it starts to leak out requiring a top up every 3 or 4 days.

 

So, how hard is it to change? I'm fairly mechanically competent & in the past I've changed the turbo, brake callipers, EGR Value etc. However, I don’t know if you need a special tool to bleed the system or if there's a particular method.

 

Additionally, I have a hunch it might be leaking from one of the two seals that seals the brake fluid reservoir tank to the top of the master cylinder. Would it be fairly simple to drain the tank with a syringe, remove the tank & replace the seals with new ones? I believe these are the right ones:

https://www.ebay.co.uk/itm/MK2-GOLF-Plug-for-master-cylinder-T1-T2-8-71-12mm-22mm-Golf-84-357611817/390752604378?hash=item5afaab90da:g:eQUAAOSwSJVap-G7&frcectupt=true

At least if it was one of these seals which were leaking it would mean that I would'nt have to remove the MC or bleed the system as it would still be full of fluid.

 

What say ye kindly folk!

[Tech1e]

You can see the reservoir leaking? That would be a first for me. The seals aren’t under any pressure other than gravity. 

 

Id be tempted so put a pressure bleeder on and see if pressure is dropping off. 

[Chris Berry]

Well, i did say it was a hunch. 😁

 

The brakes are feeling fine as far as I can tell. And, like I said, its only the last day or so since the nice warm weather in Worcester has it started to leak again.

I wonder if one of the pipe connectors is very slightly loose & is leaking?

[Tech1e]

If you are in Worcester and unsure I’d be happy to take a look. 

[Chris Berry]

That would be awesome. However, I'm at work Mon to Fri & only around after 5.30 in the evening.

If evenings arent any good, how about a Saturday? Obvously I'll compensate you for your time.

[Tech1e]

14 hours ago, Chris Berry said:

That would be awesome. However, I'm at work Mon to Fri & only around after 5.30 in the evening.

If evenings arent any good, how about a Saturday? Obvously I'll compensate you for your time.

 

A Saturday works fine for me.

[Chris Berry]

Brilliant!

 

I'll PM you well in advanced to see if you can squeeze me in!! Cant make it on the next few weekends though - family comitments.

 

With the up-coming warm weather, I'll carring a bottle of brake fluid in the car as a precaution! 😬