Braking issue

[thecremeegg]

So I took my E85 out for a drive a few weeks back and thought the brakes felt a bit spongey.

The other day I go in it to move it and the brake pedal goes to the floor. I also have one error light, the yellow triangle with a circle round it.
If I pump the pedal then nothing happens, it still goes to the floor.
Brake fluid is on low but still has fluid in it.

I've scanned the car with Carly as I've managed to lose my proper cable for the BMW software, and I've got the following errors:



Could anyone advise if I'm correct when I say it's likely a master cylinder rather than an ABS pump issue? I've ordered a used master cylinder off ebay but if it's something else it would be good to know?

Thanks

 

[enuff_zed]

If brake fluid is on low I would suggest you have a leak. If it's not a visible one anywhere then potentially back into the servo.
However, it could be that the pads have worn a lot and you've only now had cause to check the level.
If it is too low then that will upset the pressure sensors and possibly give spurious other codes.
Can't remember on the zed but a lot of cars have a diagonal split on the feeds from the reservoir in case a leak occurs in one corner. This could maybe explain why you have mention of front left and rear right?
As a very quick check you could fill up the fluid and see what happens but I suspect there is already a lot of air in the system now so you'd need to bleed it as well.

 

[thecremeegg]

Hmm yea it's hard to see any leaks on the floor, but the fact it's gone down I guess is likely indicative it's going somewhere! Pads haven't worn much, it's only done about 1000 miles in 3 years. I'm going to probably replace the master cylinder, bleed it and see what happens

 

[colb]

Brake fluid is going somewhere if no leaks from the lines then suspect and investigate the master cylinder, fluid might be getting into the brake servo. Really sounds like the seals in the master have given up so replacement probably the way to go rather than just renew the seals in the master cylinder. The Brake pressure sensors have set codes due to low pressure I would suspect, they do fail and set codes if they do go wrong. Creator 310+ Scanner can monitor them in live data. I had one fail and set a code, replaced it with a new unit from ebay which solved it.

 

[Rockhopper]

Mine had a leak from the pipe running over the petrol tank, no drips on the floor or nothing obvious but that's where it was.

 

[thecremeegg]

Mine had a leak from the pipe running over the petrol tank, no drips on the floor or nothing obvious but that's where it was.

Interesting, thanks.

Brake fluid is going somewhere if no leaks from the lines then suspect and investigate the master cylinder, fluid might be getting into the brake servo. Really sounds like the seals in the master have given up so replacement probably the way to go rather than just renew the seals in the master cylinder. The Brake pressure sensors have set codes due to low pressure I would suspect, they do fail and set codes if they do go wrong. Creator 310+ Scanner can monitor them in live data. I had one fail and set a code, replaced it with a new unit from ebay which solved it.

Yea I'm going to swap it and see what happens, fingers crossed!

 

[john-e89]

Brake fluid is going somewhere if no leaks from the lines then suspect and investigate the master cylinder, fluid might be getting into the brake servo. Really sounds like the seals in the master have given up so replacement probably the way to go rather than just renew the seals in the master cylinder. The Brake pressure sensors have set codes due to low pressure I would suspect, they do fail and set codes if they do go wrong. Creator 310+ Scanner can monitor them in live data. I had one fail and set a code, replaced it with a new unit from ebay which solved it.

Comprehensive answer, my initial thoughts too.

 

[thecremeegg]

So the problem has been diagnosed as one of the rear brake lines failing. They've been mentioned on the last few MOTs but the car does so few miles of late and has had a few big issues that I've had to sort, I never got round to sorting them!

Rather annoying as I wanted to take it to Mike at Zed Shed as he'll do front and back for £250 all in, however I can't get the car there now without paying a fortune for transport!

Anyone down here in Hampshire that can do them for me? :rofl:

 

[enuff_zed]

So the problem has been diagnosed as one of the rear brake lines failing. They've been mentioned on the last few MOTs but the car does so few miles of late and has had a few big issues that I've had to sort, I never got round to sorting them!

Rather annoying as I wanted to take it to Mike at Zed Shed as he'll do front and back for £250 all in, however I can't get the car there now without paying a fortune for transport!

Anyone down here in Hampshire that can do them for me? :rofl:

I suppose the logical answer is Ross at RBM in Hook.

 

[thecremeegg]

Yea but he wants to charge £500 which is a rip off. Every time I've tried to get anything from RBM they either say they can't do it or want to charge a fortune

 

[Zedebee]

Do you know exactly what’s failing and where? Can you see it?

 

[thecremeegg]

I don't know as I haven't been to the garage yet as away with work, but they've said one of the rear brake lines has a leak in it.
I was actually booked in next month to drive the car to Zed Shed, so obviously it breaks now lol!