No Brake Pedal....2007 C4 1.6hdi Piloted

[Doo]

I replaced the front discs & pads a couple of weeks ago which was fine. The other day I did the rears, but one caliper was knackered & the other 99% knackered, so replaced them.

I had to turn the car around, but bled the brakes 1st. Discovered the pedal was on the floor. I had brakes, but clearly unacceptable. So I tried with the Autel MaxiPRO, wen through the process, but the 3rd bleed was 106 seconds, which meant I ran out of fluid So I gave up and did it again yesterday with help from my son.

Same effect. Amazing brakes, but pedal 80% down, not good. Now It did occur to me that I was pouring in an excessive amount of fluid to what was coming out So where did it go?? I can only assume it is bypassing the master cylinder & ending up in the frying pan (accumulator).

Anyone had this issue? I once had a Talbot Horizon, where the seals flipped leaving me with only rear brakes. But I tried emergency stopping the C4 and whether forwards or reverse, the car dips to show both sets of calipers are functioning as is the ABS.

I can see it's going to be tricky swapping the master cylinder and draining the accumulator.

So, any heads up before I dive in

[Sloppysod]

Hi, not saying this will fix the problem, but, I have had similar issues, many years ago, where you can not see any air in the system but still have alow or spongy pedal.
My fix was to place a length of wood between the underside of the steering wheel and the fully depressed brake pedal overnight.
Not sure why this worked, but it did.
Good luck.

[Rp0thejester]

Could that of been air working out off the system when stationary? If no fluid leaks then I wonder if the level was correct at the time of replacing the brakes especially if both rears were knackered.

[GiveMeABreak]

Make sure you have bled it correctly - 2 operations with ESP. Here's the procedure:

Vehicles fitted with ABS or ESP have a system consisting of 2 brake circuits (which relates to your C4):

• The primary brake circuit which is the main circuit pressurised directly by the brake pedal
• The secondary brake circuit inside the hydraulic block

This braking system must be bled in 2 stages.
Following work on the master cylinder or on the ABS/ESP hydraulic block, bleed in the order:

• The right hand rear wheel
• The left hand rear wheel
• The front right wheel
• The front left-hand wheel

Following work on a brake caliper, bleed in the order:

• The caliper removed
• The right hand rear wheel
• The left hand rear wheel
• The front right wheel
• The front left-hand wheel

N.B.: If removing-refitting a master cylinder, complete the automatic bleed with a manual bleed.

Bleed procedure

CAUTION: Respect the order of opening of the bleed screws.

N.B.: There are two procedures for bleeding the braking system.
Automatic bleeding

Bleed Tool ('Tool [1]')
[1] Bleeding equipment of the " LURO" type or equivalent.
1 Diagnostic tool.

• Place the tool [1] on the brake fluid reservoir (3).
• Bleed the circuit following the instructions for use of the equipment.

When bleeding of the braking circuit is complete, check the pedal travel. If the travel is long and spongy, repeat the bleed procedure.

Manual bleeding (at the pedal)
N.B.: Two operators are necessary.

CAUTION: Switch off the ignition.

• Couple a transparent pipe on the bleed screw.
• Press the brake pedal slowly.
• Open the bleed screw .
• Hold the pedal fully down.
• Close the bleed screw .
• Allow the brake pedal to return naturally.

Repeat the operation until the fluid running out is clean and free from air bubbles.
Proceed in the same way for the other wheels.

When bleeding of the braking circuit is complete, check the pedal travel.
If the travel is long and spongy, repeat the bleed procedure.

CAUTION: Check that the wheels rotate freely when the parking brake is released .
If necessary, fill with approved and recommended synthetic brake fluid.

Bleeding

Brake circuit
This operation is performed in 2 stages:

• Carry out an automatic bleed or a manual bleed using the brake pedal (Primary circuit )
• Complete the bleed (secondary circuit) with exclusive reference to the diagnostic equipment procedure

Hydraulic clutch control (Vehicles fitted with a mechanical/manual gearbox )

Bleed the clutch hydraulic control (In the following cases ):

• Replacement of the brake fluid reservoir (4)
• Replacement of the master cylinder
• When the level of brake fluid in the reservoir (3) is lower than the hydraulic clutch control pipe

[Gibbo2286]

The secondary bleed of the abs is probably what's needed, needs to be done with a diagnostic tool, somewhere way back in my posts there's a video.

[Gibbo2286]

Here you go.

[GiveMeABreak]

The procedure is guided within Diagbox as per the procedure.

[Doo]

The secondary bleed of the abs is probably what's needed, needs to be done with a diagnostic tool, somewhere way back in my posts there's a video.

I did say I have done this twice with my Autel maxiPRO. It's very straightforward, but it does 2x25 seconds, then 106 seconds & finally 86 seconds of slow pumping the brake pedal. But my main concern is, where TH did all the fluid go???

Marc, I did the brake bleed as I have done the last 30 odd years, furthest away from the master cylinder first, then opposite rear (unless otherwise instructed, and the Autel started rear right, rear left, which is correct).

I noted the ABS pump came on and then sounded like a bigger pump cutting in for a time then off then the quieter pump sound. The pedal was doing its thing too.

I may well try to bleed it again, but as I said, I am concerned about the amount of fluid (unless I got the amount going in fundamentally wrong!

But as I said, driving around the driveway, the brakes are excellent! The hill assist works. There is no ABS light and the ABS also appears to function perfectly!

In all my years I have never come across such a fault. I have a pressure bleeder, but it uses vacuum. Pressurised air goes in the bottom of the gun, a vacuum is created in the bottle and the metre long clear pipe shows the fluid & bubbles. But I keep thinking its drawing air in at the rubber attachment as the bubbles just keep on coming. The pedal push brought out around 4 or 5 bubbles and that was it. I had my son push the pedal another 10/12 times just to ensure. Maybe I need to keep going. The whole system has new fluid so I could technically re-use the fluid this time as it is beautiful light straw coloured at each bleed screw now.

I'll let you know how I get on....

[myglaren]

It's a while since a mechanic told me this but he said that some ABS systems are bled by forcing fluid backwards through the ABS pump.

[Doo]

It's a while since a mechanic told me this but he said that some ABS systems are bled by forcing fluid backwards through the ABS pump.

Well, za Frawnch kneow heow teow bee difficile

[Doo]

I took the car for a run and the brakes seem to work just fine, despite the long pedal travel. It perfectly clear there is air in the lines though as pumping brings the pedal up for a few seconds. I did some long braking to warm them up and there is no pulling to one side or any other seeming issue. However, I did find the right front & rear brakes were luke warm to touch while the left side is decidedly warmer, meaning the right side is performing less. So, it looks like I will have to try to bleed the right side some more....

My plan is to place my (home made) ramps on the high end of the slope of the drive (where it goes down to the garage) and reverse the back end up. The ramps are around 2mtrs long by about 400mm high, which will raise the back end a good height. I leave it a while, then see if I can use the vacuum bleed to draw out any bubbles. Then i'll do the same for the front and see where we go from there.

Never a dull day

[Doo]

Left the car arse up on the ramps overnight, then with help from my lad, bled them (again ) and got some bubbles immediatly on both rears. The drivers side was worst with about 5 and the passenger side had 2. Front's had no bubbles, but we still only getting around 80% pedal. I said to my wife to drive it for a few days and I will utilise the ramps again as that did help.

Much fun....

[bobins]

Presumably the pistons in the calipers have actually self adjusted up and taken out the slack and they're not sitting shy of the disc ?

[Rp0thejester]

I'm not sure what reserving up the ramps would achieve. If the brake fluid is topped up in the engine bay then surely the front would be on the ramps not the back. Bleed the backs then top up and wait for fluid to come out of the fronts, shut them off and top up. Or am I missing a vital part, please tell me, I love to learn

[Doo]

Presumably the pistons in the calipers have actually self adjusted up and taken out the slack and they're not sitting shy of the disc ?

Brand new calipers fitted at the rear. Parking brake at 4 clicks (holds on 3 but, don't like to tempt fate and the new discs & pads need bedding in).