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Hi. Just before I spoil my bank holiday weekend, thought I would ask if anyone has a cure for my 2008 expert soft brake pedal, its a been a bit spongy for a while, however my son fitted brake pads last week, since then really soft and pressure puts the redal to the floor, there was fluid at the back of the master cylinder so changed for new, fully bled brakes until definately no more air, but still not good, plenty vacuum from pump and servo seems to be fine, going to put small amount of pressue on fluid container tomorrow and force pluid through, but still not confident will fix, also has ABS on the van, any assistance would help, but know my way around a bit so tried all the simple answers. thanks
 

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HI,

did you clamp the rubber brake pipe and open the bleed nipple before pushing back the caliper pistons as if you did not you have a chance of spinning the seals in the abs unit which means a strip down job to put seals back properly,
also you must remember that it takes quite a few miles to bed the new pads/linings in before the pedal gets it's firmness back,
did the pedal feel alright before fitting new pads/linings.
 
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The brakes tend to be very soft on the Expert anyway. New pads usually need about 100mls to bed in properly.
 

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The pedal should have at least the same firmness after a brake change as it had before the change and it should never travel to the floor (not to be confused with stopping power, you might need to press harder to stop while the brakes bed in, most people can't tell the difference in stopping power before and after a brake change).

You changed the master cylinder, it sounds like the bench-bleed may not have completely purged air from the MC. Some designs of MC's won't allow all the air to bleed when it is completely installed (Triumph TR7 comes to mind).

For proper function of braking systems, the brake fluid has to be able to return to the from the individual calipers (unrestricted back flow) or your brakes would never release when you let off the brake pedal. Unless you created a very rapid flow of fluid back to the MC, then nothing should have been able to be damaged (some systems actually require bleeding forcing brake fluid through the system in reverse).

Check for additional bleeding points on the system, there should be one on the MC, the ones at the wheels, but there may also be bleeders on or near the ABS, near or on junction blocks for the hard lines and if it has a brake force balance, there is often one on there as well (but that is old school and probably not on your van).

Lastly, and this one will suck, you may have to activate the ABS pump to completely bleed the system. This is done by a diagnostics computer (BMW requires this technique when flushing the brake system).
 

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Discussion Starter #5
Thanks for the replies. I have now used a very low pressure on the resevoir forcing the fluid through the system with the engine running, this also allowed me to bleed the ABS unit. there is no more air in this system unless its trapped somewhere at a high point. Still poor pedal, as the discs were fairly worn I replaced front discs as a matter of course, but still poor, tomorrow will have another go, the idea of the seals turning in the ABS interests me, as this may be a possibility. Happy days eh.
 

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abs seals turning

this happens a lot with vauxhalls if the brake pipes are not clamped before sending pistons back,
i always clamp brake pipe and undo the bleed nipple on the cylinder before screwing back the piston then tighten the nipple again as the piston reaches the bottom of the bore that way you hardly loose any fluid and are keeping air out the system,
do not reuse brake fluid that has been used before as it will be full of air even if it is new fluid.
you could try reverse bleeding or vacuum bleeding.
 

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I have another possibility after today...

If you have rear drums, make sure they are adjusted (I am not familiar with your van) close and then put the system back together. I had a bad pedal feel yesterday after changing all my brakes (going to the floor and spongy). The auto-adjuster had dropped off and didn't adjust the brakes the rest of the way in (I was far off from right when it was put back together. I fixed that and the pedal is better than it ever was. Also, did an old fashioned bleed with one person on the brakes and that got the last of the air out of the system.
Pedal feels solid as a rock! :)
 
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