Bleeding brake saga continues....

[the_fbi]

Decided I'd spend the evening sticking a full 5L can of brake fluid through the car using the eezibleed (tyre connected type).

Previously I've only put around 3L through so I thought going the whole hog may just eek out a bit more air.

What I've found is something very interesting.... With the eezibleed attached and purged, the pedal isn't too bad, but as soon as you take off the eezibleed the pedal is completely sh*t again.

So, with the master cylinder being fed with +ve pressure its reasonable, although not great. So I'm thinking possibly the master cyclinder is shot, although it was sold to me by somebody on here as a known working one. And very co-incidental that my old one and this "new" one are both dodgy.

I have now got a 3rd one, which I'll try tomorrow, but any ideas, other than master cylinder, spring to anybodies mind?

I was thinking that the ABS has a return circuit which returns "unwanted" fluid when the ABS cuts in, back to the master cylinder. Clearly with 20psi forcing into the reservoir this return circuit has to fight harder (if the circuit is jammed open) to feed back. So possibly I was thinking the solenoid which triggers returning fluid could be at fault (open), sound possible? Luckily I do have a spare ABS block, not 100% sure its the same but looks similar so I could try changing this.

Previous threads with more info below....

1st --> http://www.migweb.co.uk/forums/showthread.php?t=131062
2nd --> http://www.migweb.co.uk/forums/showthread.php?t=138164

Ideas appreciated although it seems to point towards master cylinder (or perhaps ABS jobby).

Ta
Regards
Chris

[Spankee]

When i fitted my 6 pots on i bleed the system 3 times and pedal was hitting the floor all the time WTF...then found out because am running ABS i needed to have the engine running and bleed the system.....got air trapped in the ABS pump did the bleed and brakes are Sh-t Hot ...................

[cavgsi]

then found out because am running ABS i needed to have the engine running and bleed the system.

never knew that

[the_fbi]

Originally Posted by Spankee

When i fitted my 6 pots on i bleed the system 3 times and pedal was hitting the floor all the time WTF...then found out because am running ABS i needed to have the engine running and bleed the system.....got air trapped in the ABS pump did the bleed and brakes are Sh-t Hot ...................

People have suggested having the ignition on, which I have, but I've not tried having it running.

I'll give that a go first, then I think its 3rd master cylinder, then new ABS block.

ta
Chris

[Astra Dan]

The ABS doesn't know if the engine is running or not.
I have completely changed the fluid in my Mk3 which has ABS without the ignition on.
The problem I think you might have is something seized in the ABS route. You are right in thinking the ABS has a return to the MC for undeed fluid, basically a set of solenoids.
I'm wondering if it's worth trying to jack the car up and get all wheels spinning, then jam the brakes on. I know the engine will probably stall, but 'forcing' the ABS to try to do something might free it up?
Or just replace the damn thing.

[the_fbi]

I'm 99% sure the more I think about it that its a solenoid stuck on bypass in the ABS block. Although why I have no idea.

I'll try smacking it about with a nylon hammer and see if it frees up. Ideally if I knew which wires did what I could just whack 12v on the correct pins and fire off all 3 solenoids in turn to loosen them up.

I guess removing/replacing the ABS block with another one at least gives me a chance to clean the loom and inner wing on that side, although its tight as a gnats bum around there.

Least its a viable solution though, and its only taken me 3 months to sort out.

It all makes sence now I know that +ve pressure on the master cylinder fluid makes the pedal stiff.

Saturday may be a good day after all......

ta

[the_fbi]

Originally Posted by the_fbi

Saturday may be a good day after all......

OK, well clearly not.....

Took the top of the ABS so I could manually fire off the solenoids to hopefully find the one which is sticking/stuck open (although I do wonder how its stuck in bypass as clearly unless the car was stopped with the solenoid fired it should be OK, unless they failsafe as bypass which is stupid for obvious reasons).

All 3 of them fire manually fine, or at least an audible click + a little vibration of the brake line, although one is slightly quieter (the connection nearest the front of the car with the yellow/black pair rather than the green/black pairs of the others).

So I thought I'd fit my spare ABS jobby, only to find out its the wrong one. Its off a 16v Cally not a Turbo. Same pipe connections just in different places so the nicely bent brakelines are not going to the correct places.

So I now need to find myself a 0 265 208 055 Bosch ABS thingy.

Still don't understand how its failed whilst in bypass mode, but fingers crossed a new ABS block sorts it.

[Dav1d]

So you are saying the abs doesn't work ?
Tried driving it and jamming on the brakes so see if the abs works (prob best on gravel or grass).
Haven't read the other threads so apologies if I'm going over old ground.

[the_fbi]

Originally Posted by Dav1d

So you are saying the abs doesn't work ?
Tried driving it and jamming on the brakes so see if the abs works (prob best on gravel or grass).
Haven't read the other threads so apologies if I'm going over old ground.

I'm sure the ABS would work fine, the problem is the ABS is stuck on bypass so all the brake effort just goes straight back into the master cylinder so you can't stop!

[Dav1d]

Have you tried getting the abs to function though?(to see if it'll free up anything thats stuck?)

[the_fbi]

Originally Posted by Dav1d

Have you tried getting the abs to function though?(to see if it'll free up anything thats stuck?)

Well I don't live on a beach and car's not MOT/TAX/Insured and has no brakes so kind of hard to get it to something slippy to try it on.

I've fired each of the solenoids off manually from the battery so thats all the ABS would do, afaik.

I even tried an Irish spanner a few times on it, didn't make a difference.
I may rebuild the ABS block this afternoon, although I'd prefer to spend £10 on a known working one, I've messaged a few sellers so we'll see.

[Dav1d]

Originally Posted by the_fbi

Well I don't live on a beach and car's not MOT/TAX/Insured and has no brakes so kind of hard to get it to something slippy to try it on.

Oh, does make things a little more difficult.