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Brake Fluid Change

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gmerry   
Sun Jun 20 2010, 12:29pm
Joined: Dec 11 2009
Member No: #21
Location: Scotland
A few Tips.

Following the Download instructions, the first task is to empty the reservoir. I used a clean disposable Baxa syringe (60p each from Ebay, see photo). The elastomer seems not to swell with the brake fluid. So removed 5 x 60ml of old brake fluid - this was very dark at only 18months old so obviously 2 year service interval change is pushing it. This is probably down to the design of the reservoir which has no diaphragm to prevent air/moisture entering the brake fluid. This is a big heavy car so brakes need to be up for it and the fluid is the critical element in this.



Next step is to remove the reservoir itself, presumably so that old sediment can be rinsed out. So first lower front windows a tad, then disconnect battery terminal. Access to the grip washer on the plastic pin/clip that attached the reservoir to the master cylinder is very difficult. Plus removing the clip will probably break the pin/clip. So decide at this stage whether the reservoir is clean enough not to need removing, or purchase before hand a new pin/clip and simply break the old one to remove. Be warned that any brake fluid residue in the reservoir will drip out over the gearbox etc (hence need to remove as much as possible with the syringe).

Connect pressure bleeding kit with suggested maximum pressure of 1.5 bar not 2 bar as in the instructions (some white stress marks showed in reservoir plastic so didn't want to push it to the official Citroen pressure). Flush calipers in correct order (FL >> FR >> RL >> RR). The front calipers have two "pots" and the lower is so far from the bleed port, that any stale fluid will not be removed just by flushing through to bleed nipple. So remove brake pads and push pistons fully home with the bleed nipple open. Then reassemble calipers with 20mm wood spacers in place of the brake pads.

Complete flushing, then reassemble with pads and perform final bleed at each wheel using assistant and brake pedal.

Road test, allowing pads to adjust to disks, cooling between each application. Check emergency brake assist (hazards will flash) and ABS functions.

Notes, LEXIA NOT required for this maintenance operation, as performed above. Bleed nipples are M7 x 1.0mm pitch and about 13mm long tip to underside of spanner hex. At least 1.5 litres of new brake fluid will be required (only use from sealed container).

Regards
G
C6Dave   
Sun Jun 20 2010, 02:31pm

Joined: Oct 01 2009
Member No: #1
Location: Northumberland
Thanks!

Have made into a permanent FAQ here: - Click Here -
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michaelb   
Sun Jun 20 2010, 03:06pm
Joined: Nov 17 2009
Member No: #14
Location: London
Why do you live so far away in Aberdeen? If you were closer I would pay you very good money to do this to mine.


I doubt any dealer would take such care.
joopajaa   
Thu Apr 26 2018, 07:38am
Joined: Sep 06 2017
Member No: #3261
Location: Byroslavia, FIN
How about the the "secondary brake circuit"? What is that? My car has a habit of heating front brakes so the pads dont disengage properly. Will try to change pads and (again) bleed the system. Do I have to use my lexia for this "secondary" part? Does it involve car off the ground (I recall that from C5 bleeding via Lexia).

From the instructions:

5. Bleeding the secondary braking circuit
N.B. : Connect the bleeding apparatus [1] on the brake fluid reservoir (4) .
Use diagnostic tools [2] or [3] .
Select the menu ESP VSC 440 .
Bleed sequence in ESP menu :
z Front left-hand wheel
z Front right-hand wheel
z Rear left hand wheel
z The rear RH wheel
Follow the instructions on the diagnostic tool .
At the end of the bleeding program, check the brake fluid level and top up if necessary .
Check the brake pedal travel (no extension), otherwise repeat the bleeding procedure .
vaho   
Fri Apr 27 2018, 07:35am
Joined: Jun 25 2015
Member No: #2228
Location: Tallinn
I think it is the system that contains separate pump for the ESP in order to brake the wheels independently and separately.
I also do not think that overheating can be solved with fluid change. The cause is rather in different moving parts/sliders or sticking cylinders. Check these out and clean or lubricate them properly or change the parts with repair kit.
joopajaa   
Wed May 02 2018, 02:11pm
Joined: Sep 06 2017
Member No: #3261
Location: Byroslavia, FIN
vaho wrote ...

I think it is the system that contains separate pump for the ESP in order to brake the wheels independently and separately.
I also do not think that overheating can be solved with fluid change. The cause is rather in different moving parts/sliders or sticking cylinders. Check these out and clean or lubricate them properly or change the parts with repair kit.


I have earlier removed the moving parts and cylinders and got them quite "loose" and lubricated. Still there is this issue. I will try with new pads and second bleeding.
MGmike   
Wed May 02 2018, 05:40pm

Joined: May 21 2017
Member No: #3151
Location: South Queensferry
joopajaa wrote ...

vaho wrote ...

I think it is the system that contains separate pump for the ESP in order to brake the wheels independently and separately.
I also do not think that overheating can be solved with fluid change. The cause is rather in different moving parts/sliders or sticking cylinders. Check these out and clean or lubricate them properly or change the parts with repair kit.


I have earlier removed the moving parts and cylinders and got them quite "loose" and lubricated. Still there is this issue. I will try with new pads and second bleeding.



I would replace the flexible brake hoses. It has been known for these to collapse internally and prevent pads from releasing correctly. Worth a try if you are going to bleed the brakes again anyway.

joopajaa   
Thu May 03 2018, 05:47am
Joined: Sep 06 2017
Member No: #3261
Location: Byroslavia, FIN
MGmike wrote ...

joopajaa wrote ...

vaho wrote ...

I think it is the system that contains separate pump for the ESP in order to brake the wheels independently and separately.
I also do not think that overheating can be solved with fluid change. The cause is rather in different moving parts/sliders or sticking cylinders. Check these out and clean or lubricate them properly or change the parts with repair kit.


I have earlier removed the moving parts and cylinders and got them quite "loose" and lubricated. Still there is this issue. I will try with new pads and second bleeding.



I would replace the flexible brake hoses. It has been known for these to collapse internally and prevent pads from releasing correctly. Worth a try if you are going to bleed the brakes again anyway.




Ok this is something new. Never changed the hoses to any car (or not at last 15 years) if there was no external damage. There might be something going on inside though. The brakes are so simple that there should not be too many failing points - no leaks either here. So this is something to consider.


MGmike   
Thu May 03 2018, 11:20am

Joined: May 21 2017
Member No: #3151
Location: South Queensferry
joopajaa wrote ...

Ok this is something new. Never changed the hoses to any car (or not at last 15 years) if there was no external damage. There might be something going on inside though. The brakes are so simple that there should not be too many failing points - no leaks either here. So this is something to consider.



It is unusual but for the price of a couple of hoses, well worth doing.
I had similar symptoms on my C5 e.g. the left front wheel dragging slightly but not enough to cause excessive heat. I decided to replace both calipers (as I found some nearly new ones at a good price) but this made no difference. Replacing the hoses fixed the problem.... and the improvement in fuel consumption more than covered the cost in a very short time.

In my case I suspect the internals had collapsed and passed fluid to the caliper when under the pedal pressure, allowing some but not all of that pressure to be released back in to the system when the pedal was released.

joopajaa   
Mon Oct 01 2018, 07:35am
Joined: Sep 06 2017
Member No: #3261
Location: Byroslavia, FIN
OK now I have new pads on all corners, new front brake hoses, new caliper o-ring on left side. I Bleeded the system 2x times as stated on Citroen manual (FL, FR, RL, RR), still the front brakes are "on" and the discs are hot.
e3steve   
Mon Oct 01 2018, 09:15am
Joined: Jan 21 2013
Member No: #1163
Location: Warsash, Hants & Palma de Mallorca, Spain
That’s an odd one. Can the wheels be rotated by hand, when the car is jacked up?
joopajaa   
Mon Oct 01 2018, 10:05am
Joined: Sep 06 2017
Member No: #3261
Location: Byroslavia, FIN
e3steve wrote ...

That’s an odd one. Can the wheels be rotated by hand, when the car is jacked up?


Fronts will turn only ½ around, rear seems to be fine. Brakepad dust all over the fronts all the time.
C6Dave   
Mon Oct 01 2018, 11:05am

Joined: Oct 01 2009
Member No: #1
Location: Northumberland
Did you open the ABS valve block ports using Lexia whilst bleeding the brakes?
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e3steve   
Mon Oct 01 2018, 01:40pm
Joined: Jan 21 2013
Member No: #1163
Location: Warsash, Hants & Palma de Mallorca, Spain
joopajaa wrote ...

e3steve wrote ...

That’s an odd one. Can the wheels be rotated by hand, when the car is jacked up?


Fronts will turn only ½ around, rear seems to be fine. Brakepad dust all over the fronts all the time.

I would be inclined, also, to disassemble the front calipers,remove the pads, reassemble and make sure that the piston pushes back into the block. Also to be certain that the ‘swingers’ that counteract onto the outer pads against the piston’s pressure on the inner pads are able to move freely in & out on their pins...
joopajaa   
Wed Oct 03 2018, 06:01am
Joined: Sep 06 2017
Member No: #3261
Location: Byroslavia, FIN
OK I did the traditional bleeding but not the "secondary circuit" bleeding (it will need to hoist the car up basically). I have to do that (never done it to any C5 or 6 since no problems like this ever occured).


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