The other day I was driving and on braking the pedal went to the floor with almost no resistance. I stopped for a while and the problem seemed to rectify itself. I had the car checked in a garage but they could find no fault with the brake system.
It was a very hot day, could this cause the brakes to overheat? Or is some other explanation for this one-off incident and how can I prevent it recurring?
It as about 10 year old astra.
I assume you have not replaced any pads or shoes immediately before the incident occurred, if you have replaced the pads or shoes the extra travel of the pedal could have been caused by the pistons in the hydraulic system reseating otherwise it could be a faulty master cylinder. I had a VW 15 years ago that intermittently did the same the cause a faulty master cylinder.
Could suggest that the brake fluid isn't perfect - mainly the fact there is an air bubble somewhere. It may sound expensive, but getting a reputable garage to replace and flush the brake fluid could save your, or someone else's, life.
if the brake fluid has not been changed as recommended then almost certainly it is a master cylinder fault.
probably a hundred or a little less for bits and about sixty quid to fit.
mrcheerful
This exact thing happened to me the other week in similar aged astra under similar conditions.
My first thought were the master cylinder; although I had changed the rear cylinders recently I thought it was too big a time gap to be related, and I couldnt get any air out of the system.
A local garage looked at it and pronounced something internal and flappy on the master cylinder had gone. New one cost me 120 quid all in, but they threw in a bottle of brake fluid ;)
Richard
Seals on the master cylinder I would say, fairly common on GM's of this age.
Tim..
Vapour lock due to water in old brake fluid ? If its old fluid it is naturally hygroscopic and over time will absorb moisture. Heat it up and water boils to vapour in system which has little if no hydraulic effect hence floored pedal ???
Far more likrely it's the master cylinder seals though. & you'll have changed all the brake fluid by the time you've changed them.
Before I replaced the brake fluid on my motorbike the front brake lever would go all the way to the handle bar. I was amazed at the state of the old fluid.. it was awful milky stuff. I guess there has to be a breather hole near the resevoir to allow air and hence moisture in to the system.
motorcycles should have a diaphragm that drops lower with the fluid, so doesn't draw air /moisture in. unfortunately people damage or don't replace the seals properly. same rules about two yearly replacement though.
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