sinking brake pedal

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Originally Posted by Outback 1

installed a brand new master cyl and it is still doing it so tomorrow it will be a full manual bleed/fluid change and see how that goes :confused::censored:without the engine running perfect pedal

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Are you aware you can use the ABS pump to pressure bleed the system??? Nanocom makes it easy,there have been posts on AULRO on how to jump a relay to make the pump run;);););););)
Im sure you will find the heads up with a search.
Goodluck
Andrew

Before you do the manual bleed try giving the modulator a work out with HDC. You don't need any hills, just put TC into low range, turn on HDC, then take it up to 40kph and lift off the throttle, and let the HDC brake you down to 7kph, then repeat 4-5 times. That should work any air trapped in the modulator internals into the main brake pipes where you can bleed out as normal.

Quote:

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Originally Posted by LandyAndy

Are you aware you can use the ABS pump to pressure bleed the system??? Nanocom makes it easy,there have been posts on AULRO on how to jump a relay to make the pump run;);););););)
Im sure you will find the heads up with a search.
Goodluck
Andrew

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The Wabco bleed procedure (and from what I've been able to find the testbook bleed also) alternates between modulator bleed which operates inlet and outlet valves plus abs pump and running the ABS pump alone. The sequence is repeated 5 times before doing a manual bleed on each wheel.

Running the pump without the modulator bleed just saves having someone to pump the pedal for a manual bleed.

cheers
Paul

Quote:

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Originally Posted by LandyAndy

Are you aware you can use the ABS pump to pressure bleed the system??? Nanocom makes it easy,there have been posts on AULRO on how to jump a relay to make the pump run;);););););)
Im sure you will find the heads up with a search.
Goodluck
Andrew

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Mr Whippy and i bled it with the nanocom last week this problem did not show up until after we had finished so now i will try a full fluid change and a manual bleed as there must be air trapped in the system somewhere :confused:

Just wondering what the problem was in the end or if in fact there was a problem.
I just did a bleed on my 2002 using a Nanocom bleed on each wheel 5 times using the Wabco procedure.
I then pressure bled the system using a pressure reservoir pump at about 7PSI. This always gives an excellent result on any car I have done.
The pedal is rock hard with engine off.
When the engine is started the pedal sloowly sinks about half way before it firms under heavy foot pressure.
However the actual braking and pedal feel are excellent and the brakes bite very high in the pedal travel and stop excellently.
To see if it made a difference I then went down a steep hill using HDC, but no difference.
Having a look at the Google entries , it seems that this behavior may be normal , but I don't know and it may have been doing it before , but I am now sensitised.
What are other's experiences.
Regards Philip A

the brake pedal does fall away on startup to about halfway.
This seems to be the case for normal operation.

Trev.

Quote:

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Originally Posted by PhilipA

Just wondering what the problem was in the end or if in fact there was a problem.
I just did a bleed on my 2002 using a Nanocom bleed on each wheel 5 times using the Wabco procedure.
I then pressure bled the system using a pressure reservoir pump at about 7PSI. This always gives an excellent result on any car I have done.
The pedal is rock hard with engine off.
When the engine is started the pedal sloowly sinks about half way before it firms under heavy foot pressure.
However the actual braking and pedal feel are excellent and the brakes bite very high in the pedal travel and stop excellently.
To see if it made a difference I then went down a steep hill using HDC, but no difference.
Having a look at the Google entries , it seems that this behavior may be normal , but I don't know and it may have been doing it before , but I am now sensitised.
What are other's experiences.
Regards Philip A

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I think Outback would be too embarassed to reply ;) He found it was normal:angel:

The D2 does have a soft feel pedal,,
it can feel very bad if you jump out of a D1(who welded up the pedal?).

Ive had the same problem after a long period of inactivity. Air trapped in system. I just used the car and it self bleeds air out. All fine after a good drive although when you first drive down the street be carefull because you dont have much in the way of brakes. Also once had a leak between the master cylinder and reservoir. Fluid was coming out over time and then air got in. I think youll find that the system self bleeds.

Good luck and be careful.

Identical experience for me, PhillipA. I've had ABS unit out twice, master cylinder out once, calipers off once, bled the system at the ABS module and at the bleed nipples as per RAVE and Wabco multiple times each,.... pedal travel is still a long stroke. I have a motorbike that is similar and the common 'fix' for it is to swap it out with a different model master cylinder. No fluid loss so I just accept it as English charm.