Leaking brake fluid

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Arya2.0S
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Leaking brake fluid

Postby Arya2.0S » Sat Sep 23, 2017 3:02 pm

So the 2.0 S still seems to be suffering from a leaky brake fluid reservoir.
Over a long period of time fluid will leak out from between the rubber seals in the master cylinder and the plastic reservoir, eventually resulting in my brake fluid getting so low the light on the dash came on the other day.

These seals have been replaced already during March with brand new ones, and the problem is the same as before. The fluid is definitely coming from this area as you can see it all over the master cylinder and over time it trickles down and accumulates on the servo and then drips onto the chassis rail, resulting in melted paint on said parts.

Brakes work perfectly fine, theres never any loss of pressure or even anything abnormal to suggest theres even a problem, you can only tell by looking at it.

Someone suggested because i have an aftermarket exhaust manifold which is bigger than the normal Ford one, the heat coming from this is affecting it, and the constant cycling between hot and cold is ruining the seals, suggesting that a heat shield would be a good idea but i dont think this theory holds much water personally, as the heat will still be trapped under the bonnet as a whole resulting in the same problem surely?

That and in all my years on Capri forums have i ever seen a single Capri thats needed a heat shield for this problem, or even anyone mentioning this in forums all over the internet.
I have however seen people put a cable tie around the master cylinder and reservoir to pull them together tighter. My one does seem a bit wobbly, and doesn't seem to sit into the master cylinder with any sort of security, so maybe thats the problem?

Any recommendations (cheap as possible as im broke at the moment) will be very much appreciated.

Paul G
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Re: Leaking brake fluid

Postby Paul G » Sun Sep 24, 2017 7:51 am

Arya2.0S wrote:So the 2.0 S still seems to be suffering from a leaky brake fluid reservoir.
Over a long period of time fluid will leak out from between the rubber seals in the master cylinder and the plastic reservoir, eventually resulting in my brake fluid getting so low the light on the dash came on the other day.

These seals have been replaced already during March with brand new ones, and the problem is the same as before. The fluid is definitely coming from this area as you can see it all over the master cylinder and over time it trickles down and accumulates on the servo and then drips onto the chassis rail, resulting in melted paint on said parts.

Brakes work perfectly fine, theres never any loss of pressure or even anything abnormal to suggest theres even a problem, you can only tell by looking at it.

Someone suggested because i have an aftermarket exhaust manifold which is bigger than the normal Ford one, the heat coming from this is affecting it, and the constant cycling between hot and cold is ruining the seals, suggesting that a heat shield would be a good idea but i dont think this theory holds much water personally, as the heat will still be trapped under the bonnet as a whole resulting in the same problem surely?

That and in all my years on Capri forums have i ever seen a single Capri thats needed a heat shield for this problem, or even anyone mentioning this in forums all over the internet.
I have however seen people put a cable tie around the master cylinder and reservoir to pull them together tighter. My one does seem a bit wobbly, and doesn't seem to sit into the master cylinder with any sort of security, so maybe thats the problem?

Any recommendations (cheap as possible as im broke at the moment) will be very much appreciated.


Are you sure you haven't got a hairline crack in the reservoir? Probably quite easy to do when wrangling the reservoir into the new seals.

Also when you rebuilt the cylinder did you put the little pin that holds the first piston in place back? if not it could be travelling past it's stop position then when the brakes are applied forcing some fluid up past the seal.

Wash the fluid that has leaked out with loads of soapy water as soon as you see it. It is hygroscopic so water will dilute it down and clean it off.

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Arya2.0S
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Re: Leaking brake fluid

Postby Arya2.0S » Sun Sep 24, 2017 1:36 pm

Paul G wrote:Are you sure you haven't got a hairline crack in the reservoir? Probably quite easy to do when wrangling the reservoir into the new seals.

Also when you rebuilt the cylinder did you put the little pin that holds the first piston in place back? if not it could be travelling past it's stop position then when the brakes are applied forcing some fluid up past the seal.

Wash the fluid that has leaked out with loads of soapy water as soon as you see it. It is hygroscopic so water will dilute it down and clean it off.


This problem existed before i replaced the seals last time, so if there is actually a crack in the reservoir then its been there for a while. Thats why i replaced the seals last time though, because of this very same problem, and prior to this i had never touched the master cylinder or the reservoir at all.
I have not done anything to the master cylinder since owning the car apart for replacing it with a brand new one before i put it back on the road in 2014, apart for replacing the seals that the reservoir sits into a few months ago.
I guess it cant hurt to drain it and see if theres any cracks, should i fill it with water and watch for leaks?

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Re: Leaking brake fluid

Postby 340truck » Sun Sep 24, 2017 7:38 pm

Try the cable tie first!
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Re: Leaking brake fluid

Postby Arya2.0S » Mon Sep 25, 2017 11:52 am

340truck wrote:Try the cable tie first!


Thats a legitimate fix then i wasnt just imagining it? lol. I 'll give it a go.

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Re: Leaking brake fluid

Postby 340truck » Mon Sep 25, 2017 4:46 pm

I used to knock the reservoir off the master cylinder frequently until I put a cable tie on. Pull it down reasonably tight and it should stop the leak.
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Re: Leaking brake fluid

Postby Arya2.0S » Tue Sep 26, 2017 5:32 pm

Right ive tied it down with three cable ties pulled as tight as i could, i also cleaned off all the old fluid off the master cylinder, heres hoping this rather ugly but super cheap fix works!
I'll keep you updated.

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Re: Leaking brake fluid

Postby ollyw » Sun Oct 01, 2017 7:27 am

Arya2.0S wrote:
I guess it cant hurt to drain it and see if theres any cracks, should i fill it with water and watch for leaks?


While still fitted to the car? Errr no. Thats pretty dangerous.

Brake fluid has a natural "search action" for finding gaps or cracks. If the reservoir is cracked I'd have thought theres plenty of new or 2nd hand reservoirs still about. It could also be that the seals you fitted aren't quite to spec. Where they from a genuine gurling or ate kit? Don't take risks with brakes. The cable tie might get you home but it shouldn't be a permenate fix.

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Re: Leaking brake fluid

Postby Arya2.0S » Sun Oct 01, 2017 1:39 pm

ollyw wrote:
Arya2.0S wrote:
I guess it cant hurt to drain it and see if theres any cracks, should i fill it with water and watch for leaks?


While still fitted to the car? Errr no. Thats pretty dangerous.

Brake fluid has a natural "search action" for finding gaps or cracks. If the reservoir is cracked I'd have thought theres plenty of new or 2nd hand reservoirs still about. It could also be that the seals you fitted aren't quite to spec. Where they from a genuine gurling or ate kit? Don't take risks with brakes. The cable tie might get you home but it shouldn't be a permenate fix.


I wasn't going to put water in the reservoir while still on the car i meant take it off and do it lol. Im stupid but not crazy haha.

I have no idea about the seals, they came off a fresh, brand new master cylinder i just swapped them over, the old seals were totally knackered and even damaged, there were chunks missing out of them and everything so no wonder it leaked and fitting brand new ones should have shown some kind of improvement yet the exact same problem persisted. So far the cable ties are working perfectly but still too early to tell because the fluid always leaked very very slowly over time and its only been a few days.
Unfortunately theres very few options available at the moment so this will have to do if it works.

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Re: Leaking brake fluid

Postby Paul G » Sun Oct 01, 2017 1:47 pm

One other way of testing where the leak is coming from is to get hold of an easi-bleed or something similar. It will pressurise the reservoir and then leaks should show up.


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