shogunswb

Brake circuit diagram 220d please.

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I've got a problem with my sons car in that after changing the rear disc's & pads the brake pedal now goes to the floor first push & won't stop the car but a second push of the pedal is ok.

It had a long travel before the change & as both rear callipers was seized thought this must have been the reason.

Clamped the flexi pipes with a proper clamp & opened the bleed nipple when pushing the pistons back & bled the calliper after fitting new parts just to make sure.

Got hold of the techstream software but there is no utility button on the ABS/.../... option so cannot bleed the brakes using the software & there are no warnings etc showing in the tech stream software.

I've clamped both rear flexi pipes & the pedal still goes to the floor so can't be anything with the rear callipers (bled the rear callipers again pushing plenty of fluid through).

I'm not convinced it's air in the system as the pedal isn't spongy once pressure has been pumped up & cannot see it's the master cylinder as there is only a little creep on the pedal with pressure applied & then stops which is quite normal for a diesel.  Not loosing any fluid so I'm at a loss.

Does anyone have a full brake circuit diagram of a 220d 2008 so that i can see what part there are other than the obvious ones?

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I can normally access the exploded diagrams but for some reason the parts list is covering the diagram for this model.

Have you clamped all the flexi hoses both front and rear?

Obvious causes are the Master cylinder (possible turned seals) and the ABS modulator block.

I take it that you have freed off the seized calipers?

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Only clamped the rears as I only changed them & yes freed them off, cleaned them up & just took them off again to make sure I wasn't being a numpty.

BUT I thought that I would take the front callipers off & the nearside bottom pin was also seized & I have just sheared off the pin trying to release it😡

Just ordered two new front callipers complete so will let you know.

For a car with 95K & a FSH thats pretty crap.

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Replaced both front callipers & the brake pedal feels better without the engine running, only goes down about half way first push & solid feel, not spongy, but when I start the engine the pedal sinks to the floor although there is more braking effect going on now, enough to engage the ABS in the wet but I don't think it would active in the dry.

Could it be something to do with the booster unit/valve?

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Checked the booster valve & that seems to be working ok but if I pump up pressure on the pedal & hold it with the engine running & then switch the engine off the pedal pushes up slightly suggesting that the booster is loosing pressure.

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