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Brake (and clutch) brake bleeding woes

Posted: Tue Sep 15, 2015 3:19 pm
by healeyneil
My braking system is all new or rebuilt and therefore dry. Filled up today and connected a pressure bleeder. Nothing happens ! tried the pedal - still nothing. Same happens on the clutch, zilch. Ive come across systems in the past where you have to prime the master cylinder in some way. Is that the case here ?
A bit p*ssed of cos the engine wont run anymore either ! ( not related - it looks like the crank sensor has died when the car was in storage I hope )
Brakes have a professionally rebuilt master cyl, many new hard lines, new aeroquip flexies, rebuilt callipers, new rear cylinders. Started the bleeding process (ha) from the furthest away rear wheel.
Suggestions welcome please
Neil

Re: Brake (and clutch) brake bleeding woes

Posted: Tue Sep 15, 2015 11:57 pm
by Jeroen
That's weird, should be fine, can't think of anything blocking the E21 lines :?

Re: Brake (and clutch) brake bleeding woes

Posted: Wed Sep 16, 2015 12:21 am
by Dammizi
had a similar problem on my e21 after 15years standing I tried bleeding the brakes and with no pressure at the bleed nipples I gave up and bought a new m/c only to find that I got the same prob, filled the m/c with brake fluid and all the pumping produced no oil pressure at the brake lines.... eventually found that afte pumping for a long time with the rear lines opened at the wheel cylinders I got a popping sound and suddenly got oil flowing out of the lines... must have been some sort of blockage in the lines, now all is working fine after a full bleed. try opening the lines exactly before the m/c and see if u get oil flowing out from there. if there is, must be some blockage somewhere in the system...

Re: Brake (and clutch) brake bleeding woes

Posted: Wed Sep 16, 2015 7:48 am
by E21-driver
If the system was completely rebuilt, it was completely empty. Then it can happen that classic pumping method is not sufficient enough to supply all the new lines and cylinder. You can it with vacuum at the bleeding nipples or overpressure max. 1 bar from the top of the brake fluid container.
There are cheap tools for that purpose available. Just try it. Then, when they start to bleed, you can go on with the classic pumping method if you like.
M.

Re: Brake (and clutch) brake bleeding woes

Posted: Wed Sep 16, 2015 8:02 am
by Jeroen
The funny thing is that he appears to use a pressure bleeder which makes the chance of this happening a lot smaller. If there are no leaks and you have pressure build up, there should be something coming from your bleed nipples, air for starters! Nothing coming out on any of the nipples, even if you completely remove them?

Re: Brake (and clutch) brake bleeding woes

Posted: Wed Sep 16, 2015 9:03 am
by polov8
With a pressure bleeder the only reason you'd not get fluid is due to a blockage, there's nothing in the system that would stop flow. I swapped out my master cylinder and slave in close succession (one failed withing a week of the other) and both times I was able to get it bled 90% of the way there with just gravity.

Re: Brake (and clutch) brake bleeding woes

Posted: Wed Sep 16, 2015 10:02 am
by pandemonium001
Has the rear bias valve been removed and the lines swapped round?
is the pedal or master rod fully returning to home? If not the fill port holes will be covered by the plunger seals, I think?
try the other wheels, might be a kinked line or a collapsed end when forming the copper

just some ideas

Re: Brake (and clutch) brake bleeding woes

Posted: Wed Sep 16, 2015 12:28 pm
by healeyneil
Thanks for the ideas from all. The above idea about the master rod returning is one worth investigating, as I had noticed the pedals werent sitting level

Re: Brake (and clutch) brake bleeding woes

Posted: Wed Sep 16, 2015 5:45 pm
by healeyneil
Lack of patience was part of the problem. Still not convinced the pressure bleeder is working right tho, but Ive got a leaking front calliper! so no more brake bleeding till thats sorted. Oh and Ive got a failing fuel pump too :(