One-third of cars face sudden brake failure

Date: 09 November 2006

Braking systems become defective when brake fluid absorbs water from the atmosphere over time, which reduces effectiveness by lowering the boiling point.

This can result in so-called 'soft-pedal', the symptom of reduced hydraulic failure, or unexpected total brake failure.

The problem is compounded because once the brake fluid cools again, braking appears normal. The problem can only be identified by testing the boiling point.

Brake fluid testing experts, Alba Diagnostics, recommends replacing fluid when it begins to boil at 200 degrees Celsius, while anything below 180 degrees Celsius is potentially lethal. However, some of the cars tested by Comma had boiling points as low as 100 degrees - the same as water.

However, cars under three years of age - the age of most business cars - performed best in the report, with an average boiling point of 228 degrees - well above the point at which Alba Diagnostics suggests replacing fluid.

Mike Bewsey of Comma said: "Once your brake fluid is contaminated, there is a much greater risk that it will boil.

"There is a real lack of knowledge amongst drivers of the importance of brake fluid and how it works. Brake fluid is a safety critical item, and it's important that this is recognised and its boiling point tested on a regular basis."

Nearly 700 cars were checked for the report.

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