Brake pedal

[Black Black]

Hi can someone help me with a brake problem ,on my 2014 yaris, last year I had new master cylinder put on, because my pedal was going to the floor, well a year later its just started happening again, there are no leaks at all anywhere, is there a known problem with the yaris master cylinder known. 

[TonyHSD]

Hi, 

I think you should go back to the place where the master cylinder was replaced and ask them to check. Only a year time if new original part was fitted correctly should not be an issue then. Perhaps it might be something else too. 
Good luck 

[Mooly]

Had something similar happen on our Corolla about 10 years ago (still have the car) where the pedal would randomly go down to the floor. This happened some weeks after new front discs and pads were fitted by a main dealer and happened coming home after a week of pretty intense use on the Isle of Man where there are some long very high speed descents where you have to be careful not to cook the brakes. In other words it was fine for quite a long time after brake work had been done.

I suspected a master cylinder but on investigation I was told it was simply air in the brake system and the dealer said that occasionally this can happen. I think they have a way of running the ABS pump while bleeding 'problem cases' to make sure all the lines are purged of air. They said it was not a common issue but apologised it happened after previous brake work had been done. It has been fine ever since.

[TonyHSD]

13 minutes ago, Mooly said:

Had something similar happen on our Corolla about 10 years ago (still have the car) where the pedal would randomly go down to the floor. This happened some weeks after new front discs and pads were fitted by a main dealer and happened coming home after a week of pretty intense use on the Isle of Man where there are some long very high speed descents where you have to be careful not to cook the brakes. In other words it was fine for quite a long time after brake work had been done.

I suspected a master cylinder but on investigation I was told it was simply air in the brake system and the dealer said that occasionally this can happen. I think they have a way of running the ABS pump while bleeding 'problem cases' to make sure all the lines are purged of air. They said it was not a common issue but apologised it happened after previous brake work had been done. It has been fine ever since.

That’s why when doing a brake bleed on cars with abs and no diagnostic tools to set the car into brake service mode it is a good idea to do so with engine running and after completing all wheels to get the car on the road, find a quiet place with dirt road and brake few times sharply to activate the abs pump , and then start with a short wheel spin to make sure all valves open and close and eventually air escapes into the brake fluid reservoir. If after that procedure there is still a sponge feel to the pedal repeat bleeding again. Job done. Similar things can happen to clutch after parts replaced and one way to fix that is slow press and sharp and quick release of the clutch pedal. All done on older car with positive experience. 👍

[Black Black]

Yes I think your right Tony ill go back to the garage and ask them , it's just a week over the warranty for the cylinder hope they'll be good to me and sort it out, thanks for your advice both.

[APS]

21 minutes ago, Black Black said:

it's just a week over the warranty for the cylinder hope they'll be good to me and sort it out,

They should. A part as critical to safety as a master cylinder most definitely has a life expectancy beyond a year (that's a slight understatement :) ). I'm really surprised you've had to have it replaced in the first place on a car of that age. As Mooly and Tony stated, ABS systems can be finicky to get all the air out of.