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Lost Brake Power


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#1 Steve_Goral

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Posted 23 December 2017 - 08:36 PM

Evening guys,

 

Had a proper brown trousers moment in the C3 Pic today, I was driving around fine for a couple of hours and then parked up for about 40 minutes.  When I got back in and set off the brakes were almost totally gone, the pedal was really spongey and needed to be pushed to the floor to get any kind of stopping power at all.  The brake power was slightly improved if I dipped the clutch and every sof often it would come back which led to some interesting driving on the way home.  When parked up if i press the brake repeatedly it provides a bit of resistance but can be pushed to the floor.

 

I've just had an MOT last week and the front brake pads came up as an advisory but that was it. Any one had a similar experience or have any pointers?  

 

 

Cheers,

 

 

 

Steve Goral



#2 Lancelot

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Posted 24 December 2017 - 12:14 AM

I don't know the C3 Pic but does the clutch and braking system share the same reservoir?   Low level?


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#3 Steve_Goral

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Posted 24 December 2017 - 06:33 AM

The fluid level seems fine, it's just below the max line.

#4 gittos

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Posted 24 December 2017 - 08:13 AM

Could be a weak flexible hose that is bulging under pressure.
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#5 stimulator

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Posted 24 December 2017 - 09:12 AM

Possible, that the brake master cylinder is junked. Or the servo. Run engine and then switch off, now pump brake pedal it should get hard,, then whilst holding foot on pedal start engine. As vacumn builds the pedal should go downwards. If this doesn't happen suspect servo or the vacumn pipes to it.
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#6 Steve_Goral

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Posted 24 December 2017 - 10:46 AM

With the engine off the pedal pumps up but will go down pretty easily.

There's also an air type noise in the passenger footwear. Am I right in thinking that's where the servo vents? Could it be a dodgy servo? In which case is there a guide anywhere how to do it?

#7 stimulator

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Posted 24 December 2017 - 10:31 PM

Yes servo vents in passenger foot well so it gets dry air. With engine off the pedal should pump up and stay hard as long as held under foot.
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Previous Xsara Picasso 20HDi, C3 SX 1.4HDi, C3 SX 1.6HDI, C4 Picasso 1.6HDi VTR+ EGS 62 Reg C3 Picasso VTR+ 1.6 HDi 92BHP

#8 discv

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Posted 25 December 2017 - 11:14 AM

If the pedal reaches the floor, and there is no fluid loss, it is a faulty brake master cylinder.


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#9 Steve_Goral

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Posted 26 December 2017 - 06:00 AM

How much of a ball ache is replacing the servo? Is there a guide anywhere?

#10 discv

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Posted 26 December 2017 - 01:25 PM

The ball ache is the realisation that a faulty servo does not cause the pedal to hit the floor  :blush: - quite the opposite in fact, the pedal remains solid at the top and requires a lot of effort to move it and get any braking.


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#11 Steve_Goral

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Posted 29 December 2017 - 03:47 PM

Right I'm almost certain it's either the pump or the pipe/valve that leads to the servo. Does anyone know a part number for the valve?

#12 stimulator

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Posted 29 December 2017 - 04:32 PM

go here   http://service.citro...angerParametres register as  private user and you will be able to look at all the parts list for your car.

 


Edited by stimulator, 29 December 2017 - 04:36 PM.

17 Reg C3 Saloon Flair 1.2 110BHP
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#13 Steve_Goral

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Posted 13 June 2018 - 07:09 PM

For fecks sake had the car in the garage when this happened and they apparently sorted it by replacing the vac pump and tonight exactly the same problem.  Could anything be causing the vac pump to fail again so soon?



#14 Steve_Goral

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Posted 13 June 2018 - 07:55 PM

My remaining thoughs are that it's the master cylinder being faulty, is it difficult to replace?  It looks like I'll have pretty much do half the work of replacing the servo so I was planning on replacing that too, the only problm with that is the rear bolts, are they super fiddly to get too?