Bleed'in Brakes!

[t-tony]

I don't remember using anywhere near 2-3 litres of fluid to be honest. I don't know what the capacity of an empty system is but I would be surprised if it were more than 1ltr. We change brake fluid regularly at work and I do not recall having any issues bleeding through an ABS pump. Possibly only because we've never had a completely empty system? But, I fitted an ABS pump on a member's Z3 a few years ago and bled it with no issues.

Tony.

 

[mrscalex]

1 litre, 250ml per corner seems to be the consensus for a straight-forward brake fluid change as I looked around the various forums at the weekend.

I have no idea how the ABS pump bleed works. But are we talking about passing 2-3 litres through when that is running?

 

[Mike68]

I normally put a liter of fluid through a brake system every two years. I don't honestly know if the master cylinder ran dry initially as it was only after I had the problem with the pedal that I thought this might have occurred and by then it had, had a liter of fluid through it. You are right about the brake hoses, I'll clamp them tomorrow.

 

[mrscalex]

I have the same issues Robert, no pedal, I do have a plan of attack though when the time comes.

Well I was thinking of you too @Sean d when I went into all the detail with Tony.

I got my old rear pipes off, all old fittings removed and new pipes bent up and installed tonight.

So we'll see if I have any better luck when I bleed the brakes tomorrow night. And when I do the fluid change in a few days.

 

[t-tony]

I normally put a liter of fluid through a brake system every two years. I don't honestly know if the master cylinder ran dry initially as it was only after I had the problem with the pedal that I thought this might have occurred and by then it had, had a liter of fluid through it. You are right about the brake hoses, I'll clamp them tomorrow.

Good luck with it Mike, I hope you get it done ok.

Tony.

 

[Stevo7682]

Wow, I used a pressure bleeder and only had about half litre in the jar afterwards, maybe thats my problem

Sean its not a pressure bleed as such when you do a full abs ( well certainly the way our Bosch one does it ) is
Once you have linked up the computer and initated the bleed program it will then tell you which corner to start from ( say it's n/s/f ) you the go yo n/s/f connect bleed hose and drain bottle to bleed nipple and open nipple then you would press confirm on diag comp .
The computer then operates the abs pump for only that circuit usually several short bursts and then a couple of long ones sometimes followed by a few short again.
To do that to just one corner usually uses anything up to a half litre or so of brake fluid it will then tell you to close bleed nipple and once you confirm that it will tell you what the next corner is so a fair bit of fluid to do all 4 so we connect our pressure bleeder purely to use it's large reserve tank so to slow the need to constantly top up fluid level.

 

[Stevo7682]

I don't remember using anywhere near 2-3 litres of fluid to be honest. I don't know what the capacity of an empty system is but I would be surprised if it were more than 1ltr. We change brake fluid regularly at work and I do not recall having any issues bleeding through an ABS pump. Possibly only because we've never had a completely empty system? But, I fitted an ABS pump on a member's Z3 a few years ago and bled it with no issues.

Tony.

Would agree Tony very rare we ever do a full electronic abs bleed ( usually only because all else has failed) like you say pressure bleed will sort pretty much most things .
I had a rear caliper fail on my skoda one weekend at the house it was raining all weekend so I wasn't out Monday morn for work system totally empty no brakes .
Took pressure bleeder home started bleed fluid pouring out caliper clamped flexi to it bled other 3 pedal solid replaced caliper following day removed clamp bled brakes mint.
Like I say only had to full abs bleed a couple of times in all else has failed situations.
@Mike68 is there any members near you that could maybe come put a fresh pair of eyes over it in case something you have missed.
Stephen.

 

[Mike68]

I'm about 25 miles South West of Inverness, so sadly I doubt there are any members within a hundred miles of me. Consolation is that I have some of the best drivers roads you could wish for on my doorstep (although not enjoying them so much in my wife's Hyundai Sante Fe ).

All the calipers are good, no leaks anywhere and I've bled each corner repeatedly with just the pressure bleeder and then yesterday with the BMW software using the ABS pump (ran it several times on each corner). I've done it with just the pressure bleeder again since then.

I'll try clamps, but I'm struggling to see air trapped below the hoses after the amount of bleeding I've now done.

No takers for the master cylinder theory?

Mike

 

[mrscalex]

I don't think @t-tony has ever given me any advice which wasn't useful. And I've sought much advice from him both on and off the forum.

So without actually knowing what the answer is and accepting I am nothing other than a novice in this area I would personally be doing as he suggested.

If you clamp off each corner in turn and you don't find/narrow down your issue then you can report back on here and see what Tony suggests next. But if you don't do the clamping it could make it more difficult for Tony to help. And Steve/others of course.

That said I would possibly be a little sceptical going into it. But in Tony I trust

 

[t-tony]

If clamping the hoses doesn't highlight any thing what I would do next would be disconnect all pipes from M/cyl. and block ports off. If pedal still crap then it must be the M/cyl.

Tony.

 

[Mike68]

OK, clamped hoses with mole grips, still no firm pedal. Took grips off and fitted G-clamps done up real tight and still no firm pedal. I'm leaving to travel for work the day after tomorrow & the kids are on holiday at the moment so I'm going to have to draw a line under this soon, but I'll post how I get on when I return.

Tony, what would you use to block off the ports?
Mike.

 

[t-tony]

You'll need 4 100mm bleed screws mate. If you can't find them send me a pm and I'll loan you some.

Tony

 

[Mike68]

Appreciate the offer Tony, but I'll just order some as they won't break the bank. The seem to come in two flavors, M10 x 1mm BPN23 & M10 x 1mm BN84. Don't suppose you know which it is?

There seem to be two pipe outlets and 2 sensors, do I just need to block the lines or sensors too. Or are there a couple more I cant see?

Mike

 

[Stevo7682]

Just the pipe outlets the sensors are fluid sealed otherwise they'd be leaking and you would see that.
Edit.
This will also allow you to bleed the master independent from the rest of the braking system.
Shame your so far up Inverness is still a good 4hrs drive north for me

 

[Mike68]

Yep, it's a long way from most places. I'll order the bleed screws and pick this up when i get back form my work trip.
Mike.

 

[Stevo7682]

Yep, it's a long way from most places. I'll order the bleed screws and pick this up when i get back form my work trip.
Mike.

Keep us posted

 

[the Nefyn cat]

Just a thought, are the calipers on the right way up? Had this problem a few years ago on a friends car, turned out he'd had the calipers off for some reason, and refitted them the wrong way round. Bleed screw should always be at the top so the air comes out upwards.

 

[Mike68]

Yes, they are all the right way up. Waiting on some 10mm bleed screws to find out weather it's the master cylinder or air somewhere else.
Mike

 

[t-tony]

Back in the day when it was worth re sealing a M/cyl. i used to fit the reservoir and fit 4 bleed nipples and pre bleed the cylinder before even fitting to the servo. Connect the pipes in turn and 1 pump on each. Job done as Edd used to say.

Tony.

 

[Mike68]

Well, I should get home from work this weekend, before I left I'd picked up two 10mm bleed nipples. I assume I need to plug the two lines with these, the two sensor ports get left alone and then see if I can get a firm pedal. If no, I'll need a new master cylinder from the stealers and if yes, get a gallon of brake fluid and re-bleed ever corner until some air finally emerges.

I feel I must be missing something as I could only see two brake lines emerging from the MC not four?

Mike