Spongy brake pedal and poor braking

[A4LLY]

After a bit of advice really. I'd recently changed my front discs and pads and rear pads. Took a while to bed in so I tried bleeding them and got some air out which solved the issue.

Last week I'd noticed they've went spongy and the pedal goes to the floor. Tried bleeding them again and got some more air out but this didn't help much. Its not leaking brake fluid though so I'm at a loss if there's air getting in.

Would a fault in the master cylinder cause this issue or is it more likely to be something else?

 

[MartinR]

Bleed a full 1 litre bottle of fluid through 250ml per caliper starting with the furthest from the master cylinder.

 

[A4LLY]

Ok. Tried bleeding them again the day. Bled each caliper through until good clean fluid came through. Still no luck though. Pedal is still going down to the floor but there is a reasonable amount of braking. The only thing that I'm not sure about us the brake fluid reservoir feels a bit loose although it doesn't appear to be leaking.

Only thing that I can think of is that theirs either air in the abs unit somehow, or the master cylinders faulty.

 

[MartinR]

All the resivoirs wobble.

Does the pedal become harder when the cars off and the pedal is pumped a few times?

 

[A4LLY]

That solves that then.

Yeah Martin. The pedal goes hard when the engines off. When it starts it goes to the floor again.

 

[MartinR]

Maybe a vacuum problem check there is no damaged or melted pipes at the back of the engine.

Tbh i would get it looked by someone asap,due to the fact of it being the brakes and endless possibilties

 

[A4LLY]

Thanks for the help. I was just hoping it would be something easier to fix. As you said could be anything though.

I've got it booked into SWR to get checked/repaired in the new year so ill not be driving it until I take it through there.

 

[MartinR]

Good luck and hope you get it sorted

 

[Bryan1]

Thanks for the help. I was just hoping it would be something easier to fix. As you said could be anything though.

I've got it booked into SWR to get checked/repaired in the new year so ill not be driving it until I take it through there.

Hi! Did you get this sorted?
Im having exact same issue.

 

[A4LLY]

Hi! Did you get this sorted?
Im having exact same issue.

Just needed bleeding again, they got more air out. They pressured the system up and couldn't find any leaks. He did say that when they took it out to try the brakes felt quite sharp so it's obviously done the job. It's been fine since but mike did say just to keep an eye on it incase they do go again.

He did say that they've rarely had to change master cylinders on them.

 

[Bryan1]

Glad you sorted it!
My pedal is soft and hit the floor only for the first time braking then firms up thereafter, going to try a fluid flush and proper good bleed, hope this cures it.