Brake Failure

[Bluemx16]

Hi, I have an 02 Avensis D4D which just failed the MOT on the brakes. A couple of times when driving the pedal has been rock hard and the light came on, then the next time it is ok. All so when the examiner pumped up the pedal then started the car the pedal stayed rock hard instead of sinking. Anybody got any ideas?

[gazza1286]

That sounds like a brake servo fault. These have no serviceable parts and are replaced complete. However there could be a problem with the hoses connecting it to the intake manifold or the non-return valve (if there's one fitted).

They generally last the life of the car so buying from a breaker isn't a problem.

[Bluemx16]

Thanks Gazza, I'll check the hoses first.

[Mike169]

Hi Stephen

it is often the hose that goes but it self destructs internally so checking it is challenging as the hose deteriorates inside and the internal walls close together when the vacuum is being generated. If at all possible try and check the hose internally, see if any rubber flakes out, possibly even take it off the servo end, run the engine and see if you get a good 'suck' on the hose with your finger over the open end and try and see if the walls of the hose appear to close in towards each other. If in any doubt just fit a new hose, a genuine one, heater hose won't do, as if you end up changing the servo you'll end up changing the hose anyway.

Mike.

[Bluemx16]

Thanks Mike.

[Devon Aygo]

When was your vacuum pump last serviced? A hard pedal can be a lack of brake vacuum assistance to the servo, the pump should be overhauled every 10 years or 120,000 miles whichever is soonest

[Bluemx16]

Hi Lee, not sure when it was last done, I've only had the car for about 8 months.