Defective brake fluid could put motorists at risk

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Wed 20 Aug 2014 09:07
Defective brake fluid could put motorists at risk - Trilogy

www.autocar.co.uk/car-news/motoring/how-defective-...k

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Wed 20 Aug 2014 10:28
Defective brake fluid could put motorists at risk - RobJP

The headline should really be "Lack of maintenance could put motorists at risk".

Considering how few people ever even check that their tyres are at the correct pressure, or even if their tread depths are legal and safe, then a lack of brake fluid checking or changing doesn't surprise me.

A few weeks ago, I waved down a lady driving a Galaxy, with 3 kids in the back. Waved her down because, even from 50 yards away on a busy street in town, it was obvious that she had a flat, it was making a huge racket. Properly flat too, not just low pressure. Pointed it out to her, and she basically shrugged and said she'd "try to get it into the garage". I offered to change it for the spare for her, if she had one. She replied that she was 'running late'. I then noticed that all 3 kids were bouncing around in the back, no safety seats or seatbelts.

Was I surprised ? sadly not.

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Wed 20 Aug 2014 11:00
Defective brake fluid could put motorists at risk - thunderbird

Won't be long before some muppet posts saying they have not changed their brake fliud in 20 years claiming its all a money making conspiracy.

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Wed 20 Aug 2014 12:32
Defective brake fluid could put motorists at risk - Cyd

Unfortunately there are people who actually believe this.

Defective brake fluid not only can lead to boiling when braking under duress (rendering the brakes useless), but also reduces the effectiveness of both ABS and ESC even if boiling has not occured. Both these systems rely on precise movements of the actuators to provide precise control over the wheels.

Since ABS is already mandatory and ESC almost certainly will be soon, it is my opinion that a simple moisture check at the master cylinder should be included in the MoT. Or manufacturers could develop a moisture content detection system within the ABS block or master cylinder linked to the ABS warning light.

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Wed 20 Aug 2014 13:37
Defective brake fluid could put motorists at risk - madf

I know a TR7 owner (and poster) who will tell us his fluid is 120 years old and as good as new...

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Wed 20 Aug 2014 13:56
Defective brake fluid could put motorists at risk - Cyd

Yes. More fool him.

It's even more important on older cars as the materials used in the flexible hoses and seals isn't as good as it is today. These materials were significantly improved between 10 and 15 years ago (from the major brands at least). Brake fluids have improved too (major brands again) but the problem can never be erradicated completely.

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Wed 20 Aug 2014 14:00
Defective brake fluid could put motorists at risk - skidpan

I know a TR7 owner (and poster) who will tell us his fluid is 120 years old and as good as new

Would that be the same TR7 owner who never changes his oil or his tyres?

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Wed 20 Aug 2014 15:12
Defective brake fluid could put motorists at risk - madf

I know a TR7 owner (and poster) who will tell us his fluid is 120 years old and as good as new

Would that be the same TR7 owner who never changes his oil or his tyres?

You have him in one.

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Wed 20 Aug 2014 22:38
Defective brake fluid could put motorists at risk - focussed

Could someone explain how or by what process water/moisture gets into brake fluid?

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Wed 20 Aug 2014 23:07
Defective brake fluid could put motorists at risk - RT

Could someone explain how or by what process water/moisture gets into brake fluid?

Brake fluid is hygroscopic - the brake master cylinder isn't air-sealed - the flexible brake hoses and rubber seals allow water to be diffused into the fluid.

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Thu 21 Aug 2014 00:40
Defective brake fluid could put motorists at risk - Andrew-T

Could someone explain how or by what process water/moisture gets into brake fluid?

Brake fluid is hygroscopic - the brake master cylinder isn't air-sealed - the flexible brake hoses and rubber seals allow water to be diffused into the fluid.

I'm not sure this is the whole explanation. I think much of it is simply condensation during the heating and cooling cycle that takes place in the engine compartment between driving and parking overnight. Air is gently sucked into the master cylinder during the cooling phase and any moisture is absorbed by the fluid. A tiny amount each time, but it accumulates.

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Thu 21 Aug 2014 08:03
Defective brake fluid could put motorists at risk - Cyd

- the flexible brake hoses and rubber seals allow water to be diffused into the fluid.

This is true. Materials have improved over the years to reduce the effect.

Edited by Cyd{P} on 21/08/2014 at 08:04

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Thu 21 Aug 2014 23:23
Defective brake fluid could put motorists at risk - focussed

Could someone explain how or by what process water/moisture gets into brake fluid?

Brake fluid is hygroscopic - the brake master cylinder isn't air-sealed - the flexible brake hoses and rubber seals allow water to be diffused into the fluid.

But all modern master cylinder reservoirs have a rubber concertina diaphragm separating the fluid from the atmosphere. All four of my vehicles have this, a car a truck and two motorcycles. As the level rises and falls the diaphragm follows the fluid level, so the brake fluid is not in contact with the atmosphere.

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Wed 20 Aug 2014 23:22
Defective brake fluid could put motorists at risk - The-Mechanic

Brake fluid is hydroscopic so it will absorb moisture from the atmosphere. The fluid reservoir is not an airtight container as it needs to allow for the fluid level to drop as the brakes wear because if it were totally sealed it would create a vacuum in the reservoir.

The older the fluid, the more moisture it will absorb. This in turn lowers the effective boiling point of the fluid by allowing the moisture (water) to boil away under heavy braking causing air pockets from the steam produced by the boiling water. Air is compressible so the pedal will sink lower to compensate which can, in extreme circumstances mean the pedal being pressed fully to the floor with little braking effort being applied to the wheels.

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Thu 21 Aug 2014 11:44
Defective brake fluid could put motorists at risk - veryoldbear

I blame this modern electronic brake fluid myself ...

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Thu 21 Aug 2014 17:42
Defective brake fluid could put motorists at risk - AlexT

I know, here even mechanics don't feel the need to change brake fluid, last time I changed my pads, I told him to also change the fluid and he looked at me and said "but the car is quite new, only 4 yrs old, why change the fluid? He was surpised when I showed him on the bottle of brake fluid "change every 1 year".

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Thu 21 Aug 2014 18:43
Defective brake fluid could put motorists at risk - madf

I know, here even mechanics don't feel the need to change brake fluid, last time I changed my pads, I told him to also change the fluid and he looked at me and said "but the car is quite new, only 4 yrs old, why change the fluid? He was surpised when I showed him on the bottle of brake fluid "change every 1 year".

And I read stuff about only qualified machancis being allowed to work on cars.

ROFL: that would mean a waiting list for servicing of 100 years... or more.

The "mechanic" trade has some very competent people - and an awful lot who know no more than the "expert" who taught them.

I have a collection of spanners and lamps donated by them to show how professional they are .......not. In one case, still attached to the suspension....

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Thu 21 Aug 2014 19:34
Defective brake fluid could put motorists at risk - Andrew-T

<< I have a collection of spanners and lamps donated by them to show how professional they are .......not. In one case, still attached to the suspension....>>

Yes, I remember (way back) finding a ring-spanner beside the sump on a Mini after a service.

But then the fitters who replaced a sealed-unit on our conservatory roof recently left a pair of pliers on the house roof nearby.

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