Brake Bleeding Issues

[mhyphenl 10 1 Cars]

I've finally got to MOT stage apart from the damn brakes. I must have bled them 4 times and still unable to apply much pressure, still a little spongy but fairly solid when you press with the engine off. All the pipes are new, calipers fairly new, it's got ABS and the associated compensators which have been freed off well, there aren't any leaks that i can find

I used a self bleed spare tyre jobbie which is slow as hell on the rears, a bit better on the fronts but I put this down to the compensators.

Are there any tricks I could use or any areas that can cause issues?

[HERMAN 33]

Try a syring to suck it through.

Neil

[rallyeash 155]

Get somone to operate the pedal up and down and crack off the nipples and close accordingly

[matt.f 16]

Presume you made sure it had 20psi in minimum

[welshpug 1,646]

you need to bleed the rears with the car on the ground.

[Matt205 14]

My pressure bleed kit wasn't slow, but it did benefit from applying some pedal pressure a well to dislodge air as the system was dry and don't forget to follow the Haynes manual bleed order and remembers the process if you have a compensator to pump the pedal 4 or 5 times after the 1st read wheel.

[allye 530 3 Cars]

Are you getting plenty of fluid through the rears? It could be the compensators packed up, where they standing long dry and not in use?

[mhyphenl 10 1 Cars]

Many thanks for all your comments. Yes plenty of pressure in the tyre, even tried a little too much at one stage. Also done the 2 man pedal method, this got me much further and the brakes do work now, but no where near safe.

 

Are you getting plenty of fluid through the rears? It could be the compensators packed up, where they standing long dry and not in use?

 

This is where I think some of the issue is, the rear compensators where off the car for a good while and as all the pipeing is new it was a dry system. The fluid to the rears is very slow and although the car is on the ground i think the suspension is set too high. I realised that the compensators might have been an issue but they were freed off well before fitting and I've even tried holding them back to make sure they're not activating. Fluid does flow through them and its the overall braking thats poor so I'm sure there is air somwhere. If there was no air but rear compensators were poo what would be the effect?

[Anthony 1,002]

Are you sure that it's a hydraulic issue?

 

Used and/or mismatched pads and disks can give a horrendously spongy pedal and very underwhelming brake effort until they bed in properly.

[mhyphenl 10 1 Cars]

Are you sure that it's a hydraulic issue?

 

Used and/or mismatched pads and disks can give a horrendously spongy pedal and very underwhelming brake effort until they bed in properly.

 

I really can't be sure as I've only been able to drive it down my road and back since rebuilding as it has no MOT or Tax or insurance for that matter! What is the best way to identify the issue, the pedal seems quite solid when pressed whereas when i first bled it the pedal went to the floor with no resistance . The car stops but i wouldn't want to avoid hitting somthing!!!

[Anthony 1,002]

One other thought - have you triggered the ABS since bleeding the brakes?

 

No experience of it on 205's, but on 306's I've had it a couple of times where bleeding the system after it has been drained just won't give a decent pedal, and instead always feels spongy once the engine is running. In those cases, it's (I'm assuming) been air that is trapped in the ABS unit somewhere, and the fix is to drive down the road (or better still a gravel track or similar) and just stand on the brake pedal so the ABS triggers on all circuits, purging the air.

[mhyphenl 10 1 Cars]

One other thought - have you triggered the ABS since bleeding the brakes?

 

No experience of it on 205's, but on 306's I've had it a couple of times where bleeding the system after it has been drained just won't give a decent pedal, and instead always feels spongy once the engine is running. In those cases, it's (I'm assuming) been air that is trapped in the ABS unit somewhere, and the fix is to drive down the road (or better still a gravel track or similar) and just stand on the brake pedal so the ABS triggers on all circuits, purging the air.

 

Now then, the last attempt to bleed was the 2 man brake pedal job and we did get very fine bubbles at the ABS unit, the ABS isn't working currently (thats the next job!) but i could activate the ABS pump directly from the ABS ECU connector, then go through the process again! I'll have to do it like that as standing on the brake probably wouldn't lock the wheels at the moment!!

[welshpug 1,646]

you need to bleed the rears with the car on the ground.

Are you doing this?

[mhyphenl 10 1 Cars]

Are you doing this?

 

On the last attempt yes and the flow was better, however just to clarify. If the back end is lifted up does this shut off the compensator and stop the flow of brake fluid? I've never really looked at how these work. Is the lever held shut in normal operation and only allowed to open if the back end starts to lift? Or is it allowed to open in normal operation and held shut if the back end lifts?

[Anthony 1,002]

ABS compensators work on the position of the rear suspension, so with the car in the air and suspension at full droop, the compensators will be closed.

[DamirGTI 340]

Ditto , no experience on a ABS fitted on 205's , but on most new ABS systems usually if the pedal feel is not good after a bleeding process the ABS unit needs to be connected to some kind of spec. tool in order to purge the air bubbles and reset the ABS electronics .

 

Damir

[mhyphenl 10 1 Cars]

I'll go through all the diagnostic tests on the ABS which include activating the pump for a couple of seconds as it needs doing anyway! Hopefully that will clear some air and re bleed all round. Need to figure out which way round the compensators work and wether the suspension is too high and make sure it's not these kicking in that os preventing flow to the rears. I assume that the rear brakes get less flow anyway even when fully open as generally you want more braking power to the front?!?

[nixonmi16 5]

best way to test if you still have air in the system is clamp off all 4 hoses and see if the pedel goes hard if so remove them 1 by 1 this will show the problem line. but as said before replacement pads/discs can cause a springy feel till beded in. as long you have a hard pedel with a small amount of travel on first push without the servo you should be fine. 1 thing worth checking some rear pads have a lug on the back to line up with the piston if its not it can cause a poor feel.

[minimaniacwhyard 17]

You can try gravity bleeding. Ive had this issue on. Motors in the past when the system gets drained the abs needs to be bled via a diag tool or "worked" down the road. When this has not been possible due to wiring issues we have Filled master cylinder right up attached an extra bit to the top with more fluid in. Then open the bleed srees slightly over night this should force air out slowely. Has worked a couple of times