Bruno

Hi.

I presume you are simply bleeding, not replacing fluid following a caliper replacement or something. These are the basic principles:

1. Keep the end of the pipe under fluid in the collecting bottle - dont trust the eazibleed valve to not suck air in.

2. Keep the master cylinder fully topped up, do it gently.

3. Pump not in a frenzy, but firmly, 4 pushes, hold, bleed, slowly raise your foot after the bleed, pump again....

4. Go around the car five times. 1 litre should be enough.

If you have ABS the ignition must be on, otherwise the the hydraulic pump wont open up the valves and clear.

The trick I've found which makes the greatest difference is to get the car up on axle stands on all four sides, with the rear of the car up higher - say six inches - than the front. Then use a hydraulic jack to push up the rear beam enough to bring the hubs in line with where they would be if the car was sitting on its wheels normally. This is important, as it enables the rear axle to open up its proportioning valve. If the rear beam is allowed to drop, the proportioning valve almost closes in the beam, the air gets trapped just before the valve.

Then lift your handbrake to the hilt. This compresses the rear calipers, forcing air to divert to the bleed valves rather than collect inside the pistons.

• If you have ABS bleed in this sequence: rear right, rear left; front left, front right. But before you start, turn the ignition on, dont start the engine.
• If you dont have ABS it is rear right, rear left, front right, front left. Use a high grade 

If it doesn't clear, or if you have had to replace a caliper, etc (and therefore the m/c lost pressure) then get a pressure bleeding tool - these contain a bottle with a pump (look similar to a garden weed sprayer, but with an extra pressure guage and cap to go over your master cylinder). This creates an overhead of fluid in the master cylinder and repeat the above process.

If that doesn't clear the problem you could have a frozen caliper somewhere. Check each caliper one at a time.

• Dismount it, prove to yourself that the piston can retract properly. 
• Stick a two inch piece of wood between the piston and the receiver.
• Pump the piston to enable it to extend - and prove to yourself that the piston doesnt stick.  
• Refit when sure, go to the next one.

If the pistons on all four calipers do move smoothly, then get a bright torch and peer it down the master cylinder's reservoir and look for signs of small bubbles appearing when the pedal is pumped. If that happens it is likely that the m/c is knackered. 

If you are sure the m/c is good, then the last resort is a negative pressure bleed - which needs a garage properly equipped to do that. That always works. An experienced mechanic can usually tell, whilst pumping, if the problem is the m/c, the ABS pump, or an end caliper.