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How to bleed the accumulator type ABS brake system
Hi All,
After replacing my two front brake callipers I thought it would be a easy job to bleed air out of the system.... I was wrong. I started with a "traditional" bleeding process with nipples, some tubes and 2 persons.
My brake system:
http://s64.photobucket.com/user/Sasi..._1962.jpg.html
During the night with the brake callipers removed, I expected fluid to stay inside the open brake tubes, as I had the pedal being pushed and hold down. This didn't work, some fluid came out anyway during the night.
Now, there seems to be some air trapped in the ABS/ESP- accumulator system. I did several bleeding combinations without any success... and an pedal without normal brake response.
1) Are there some options to bleed the trapped air out of the system without the use of an special diagnostic tool the Intelligent Tester Tool II?
2) Is there an hidden nipple on the ABS/booster module?
3) Or is there some methods to get the ECU in a "bleed" mode?
Experiments I've done so far... without getting the air out:
Pumping out air with ignition OFF went OK --> Brake pedal got firm again.
Switching ignition ON (engine off) --> electronic pump pumps ~30sec - when pushing the pedal, its totally empty feeling, as if all the oil is gone and I'm pumping air... when pedal is pushed, electronic pump kicks in...sound is like air is being pumped.
Ignition OFF --> a few pumps and its firm again
If pedal is firm --> while switching ignition to ON --> sound of the pump is as if it's pumping some oil during the first second / the first pedal stroke, then it gets an empty sound "air pumping sound". If ignition is switched off and on again, same short oil pump sounds returns, followed by empty air pump sound.
When bleeding nipples are opened after pressing pedal:
- when ignition is OFF --> no air comes out of the tubes, only fluid
- when ignition is ON--> no air comes out, like with ignition off, but pumping feeling is as an "empty feeling" as with closed nipples. It feels as I'm only pumping air. This is what I expected, as the booster helps with pushing out the fluid
Closing the nipples:
- when ignition is OFF --> pedal is immediately firm,
- when ignition is ON --> empty "air" pumping feeling remains a few pedal strokes, than suddenly within one stroke, it gets firm again --> as if some volume is filled up with oil, which is pumped empty when ignition is switched ON.
When engine is started, effect is same as with ignition ON, however --> after few strokes of the pedal, all lights ABS/VSC show a Christmas tree, beeper beeps loud and pump doesn't stop anymore after 30 seconds --> as if some other internal area was emptied now as well.
I'm pretty clueless what to do next. All help is appreciated!!
After replacing my two front brake callipers I thought it would be a easy job to bleed air out of the system.... I was wrong. I started with a "traditional" bleeding process with nipples, some tubes and 2 persons.
My brake system:
http://s64.photobucket.com/user/Sasi..._1962.jpg.html
During the night with the brake callipers removed, I expected fluid to stay inside the open brake tubes, as I had the pedal being pushed and hold down. This didn't work, some fluid came out anyway during the night.
Now, there seems to be some air trapped in the ABS/ESP- accumulator system. I did several bleeding combinations without any success... and an pedal without normal brake response.
1) Are there some options to bleed the trapped air out of the system without the use of an special diagnostic tool the Intelligent Tester Tool II?
2) Is there an hidden nipple on the ABS/booster module?
3) Or is there some methods to get the ECU in a "bleed" mode?
Experiments I've done so far... without getting the air out:
Pumping out air with ignition OFF went OK --> Brake pedal got firm again.
Switching ignition ON (engine off) --> electronic pump pumps ~30sec - when pushing the pedal, its totally empty feeling, as if all the oil is gone and I'm pumping air... when pedal is pushed, electronic pump kicks in...sound is like air is being pumped.
Ignition OFF --> a few pumps and its firm again
If pedal is firm --> while switching ignition to ON --> sound of the pump is as if it's pumping some oil during the first second / the first pedal stroke, then it gets an empty sound "air pumping sound". If ignition is switched off and on again, same short oil pump sounds returns, followed by empty air pump sound.
When bleeding nipples are opened after pressing pedal:
- when ignition is OFF --> no air comes out of the tubes, only fluid
- when ignition is ON--> no air comes out, like with ignition off, but pumping feeling is as an "empty feeling" as with closed nipples. It feels as I'm only pumping air. This is what I expected, as the booster helps with pushing out the fluid
Closing the nipples:
- when ignition is OFF --> pedal is immediately firm,
- when ignition is ON --> empty "air" pumping feeling remains a few pedal strokes, than suddenly within one stroke, it gets firm again --> as if some volume is filled up with oil, which is pumped empty when ignition is switched ON.
When engine is started, effect is same as with ignition ON, however --> after few strokes of the pedal, all lights ABS/VSC show a Christmas tree, beeper beeps loud and pump doesn't stop anymore after 30 seconds --> as if some other internal area was emptied now as well.
I'm pretty clueless what to do next. All help is appreciated!!
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