Brake Help Needed

[LH16v]

Hi, need a little help. Phase 2 19 16v with bosch abs.

Handbrake wasnt working so found that rear calipers were in terrible condition.

Removed and replaced calipers and bled the rear brakes.

Test drove the car and the brake peddle felt very soft. I could press the peddle almost to the floor and when the peddle was at the bottom the brakes would kick in. At least they worked.

Thought that this might be because of air in the system. I tried bleeding the last caliper that I put on (rear right) and pretty much no brake fluid came out when pressing the brake peddle.

I did not bleed any of the other brakes as I ran out of time this morning so put everything back and noticed that now the front brakes are stuck on.

All brake lines and hoses look in good condition and i have been unable to locate any holes or anywhere that air could enter the system.

What have I done? Could this be that the rear bias valve is not working and has built up pressure at the front of the braking system? The brake fluid reservoir is just under the max line so it has enough fluid.

Any suggestions?

 

[Chris H]

the ABS modulator is probably the issue here, there should be 2 bleed nipples on it

 

[LH16v]

the ABS modulator is probably the issue here, there should be 2 bleed nipples on it

Thanks for the reply.

The Haynes manual doesn't seem to like people working on braking systems with abs, it doesn't say much.

Is the abs modulator under the brake fluid reservoir? How much needs to be bled? How would the modulator stop fluid from reaching the rear brakes?

Sorry for all the questions.

 

[LH16v]

If I bleed the whole system will this also bleed the ABS module? Or is the ABS module seperate and requires bleeding independently?

 

[Chris H]

yes it will but won't help much if there is air trapped in the modulator.

Turn the ignition on and off a good few times to cycle the unit (does a solenoid check) that might purge it to release the brakes then try bleeding again.

 

[LH16v]

yes it will but won't help much if there is air trapped in the modulator.

Turn the ignition on and off a good few times to cycle the unit (does a solenoid check) that might purge it to release the brakes then try bleeding again.

Thanks for the reply. If I bleed the system and get the brakes operational (i.e. not jammed on) take for the car for a drive and try to make the ABS kick in, will this eventually push any air lock out of the modulator and towards the calipers?

 

[Chris H]

might do, might not, you'll soon know by the fact the pedal will drop a bit further.

 

[LH16v]

I bled the brakes twice, some air and some 5 or 6 year old brake fluid came out and now the brakes have freed up. The brakes feel better than ever, probably because they are now running on new fluid.

ABS seems to be working (or at least the light on the dashboard is not coming on whilst driving) so I take that as a good sign. I suspect that there probably is a small amount of air left somewhere in the system but I will bleed the system again once it becomes more noticeable.