After driving around for about an hour I did a turn to line up with the driveway to reverse in. But the brake pedal went straight to the floor before the car stopped. I kept pressing the brakes as I went into the driveway and sometimes it worked fine (perhaps not the normal way, just not to the floor) while other times it went to the floor.

 

I've not done any work on the car for a few weeks, and I've driven ~300 miles without any issues. Saying that...

The last work I did was replacing the springs on the one of the rear drum brakes (the little ones that point outwards) as one had fallen off. This seems to have worked fine so hopefully I didn't break something!

I'm pretty sure ~3 years ago the master cylinder & a slave cylinder was replaced. 

 

What I've checked so far

- Fluid in the reservoir is full

- Holding my foot on the brake with the engine off, the pedal stays in one place

- Having my foot on the brake, turning the engine on, the pedal slowly sinks (not to the floor)

- Turning the engine off and pumping the brakes, it slowly gets harder

- No leaks at the master cylinder by the looks of it

- No leaks around the ABS thing

- I've taken each wheel off and there are no obvious leaks

- I think I found the slave cylinder that was replaced with the master cylinder, but i'm not sure if it's seated correctly? I've looked under the seals and although one looks a little wet, i'm not sure if i'm just seeing things. There's also something white but I don't know what that is. Here's a link to some pictures - https://imgur.com/a/SUf276i

 

The last thing I can do is bleed the brakes but i'm not sure where the air has come in, and why its occurred suddenly? The heat? If this doesn't work I might have to change the master cylinder.. 

 

Any thoughts? 

I suspect the master cylinder, those wheel cylinders look dry to me.

7 minutes ago, sepulchrave said:

I suspect the master cylinder, those wheel cylinders look dry to me.

 

They look dry, which is a good thing? Wooo

 

That seems like a short lived master cylinder? If it's not leaking, is the symptom just a poor pedal? Or perhaps it'll leak over night like it did last time ☹️

 

I think i'll bleed the brakes (practise!), nervously drive it and if it's still there I'll replace the master cylinder. Thanks for your reply

Did the ABS block get bled after changing the master cylinder?

If not, it's air trapped in the valve block.

4 minutes ago, sepulchrave said:

Did the ABS block get bled after changing the master cylinder?

If not, it's air trapped in the valve block.

It was taken to a garage and I'm not sure what they did. But this was ~3 years ago so hopefully there's no air from that 😛

 

I'm following the Haynes manual and It only says about bleeding the 4 brakes. Should I be bleeding other stuff too?

1 hour ago, OJSkoda said:

I'm following the Haynes manual and It only says about bleeding the 4 brakes. Should I be bleeding other stuff too?

 

No, just the four brakes if there's no air in the ABS block. I find a Gunson Eezibleed works well to bleed them.

Edited 25 June, 20205 yr by TMB

I've bled the system and replaced maybe 400ml of DOT4. It was pretty dirty and hasn't been changed in a few years, so I'd like to think it just got hot and caused some air bubbles. It seems to be working okay now.... 🤔