Long time problem with my brakes....Ive been bleeding them every bloody week for 2 years.......as well as replacing various different components.

Vacuum Unit replaced.
Main Cylinder replaced.
Brake pads.
Seals.
Pistons
Keep getting lots of air in. Pedal will be firm and gradually get lower and lower until they are almost not working at all.

Starts solid and gradually gets softer until its being pushed all the way to the floor.

Im thinking next step is hoses.

Would the air be getting in via a dodgy ABS unit?

Your car seems too young to have porous flexi pipes yet. Regards

David

Lovely i6 has now gone, but not me......

Please let me know if anything in my post offends you, as I may wish to offend you again......

gavmoulds wrote:

Long time problem with my brakes....Ive been bleeding them every bloody week for 2 years.......as well as replacing various different components.

Vacuum Unit replaced.
Main Cylinder replaced.
Brake pads.
Seals.
Pistons
Keep getting lots of air in. Pedal will be firm and gradually get lower and lower until they are almost not working at all.

Starts solid and gradually gets softer until its being pushed all the way to the floor.

Im thinking next step is hoses.

Hi

Are you actually able to see air bubbles coming out out (clear Tube into a jar with clean brake fluid) when you bleed the system. Does the brake pedal remain firm with the engine off, Or are you experiencing what is know as diesel pedal creep with the engine running.

Diesel engine vehicles usually use a pump to generate the vacuum for servo assistance. Unlike the inlet manifold of a petrol engine, there is no vacuum relief with a pump. If excessive pedal pressure is applied when the vehicle is stationary (and the engine is running) the hydraulic pressures required to stop the vehicle will be grossly exceeded and fluid will be forced past seals that are between circuits. Larger vehicles such as vans and 4x4s are more prone to this problem as they use servos with a higher boost ratio. The phenomenon is known as diesel creep; and it is often incorrectly diagnosed as being caused by a faulty master cylinder.

If this us the case you my be trying to fix something that isn't a problem, and just a characteristic.

Silly question but have you checked all the joints for tightness?

gavmoulds wrote:

Keep getting lots of air in. Pedal will be firm and gradually get lower and lower until they are almost not working at all.

Starts solid and gradually gets softer until its being pushed all the way to the floor.

There would be fluid showing some where it cannot just disappear

but he doesnt say the fluid level is dropping - only air getting in Jules

Weak or missing front pad springs will give the symptoms you describe. These:


 Past: FL2 TD4 HSE Auto
Evoque SD4 Dynamic Lux Auto
Present: Audi A3 S Line.

The system can only take so much put any amount of air in I know it compresses but the will be a rise in fluid when engine not running

The brake fluid doesnt compress while the engine is running. If it did, the brakes would come on. For the same reason, the brake fluid won't rise when you switch the engine off. Past: FL2 TD4 HSE Auto
Evoque SD4 Dynamic Lux Auto
Present: Audi A3 S Line.

No l Meant air compressing

Steve D wrote:

Weak or missing front pad springs will give the symptoms you describe. These:

Jules, it doesn’t cause air to enter the brakes but if the springs are weak or missing, the caliper is not held parallel to the disc and the piston is pushed back into the caliper. Because of this, the first push on the pedal is spent straightening the caliper up which give the same symptoms of air in the brakes. A badly worn wheel bearing will also give the same symptoms but you would usually hear that. The OP hasn't confirmed that air is coming out when he bleeds the brakes. I’ve been in the motor trade for over 45 years and have seen a missing or weak spring cause this on more than half a dozen occasions. In fact, only a few weeks ago a mate of mine (also a mechanic) had the same problem on a customers Focus and that turned out to be a missing spring. He found out only after bleeding the brakes several times! Off the top of my head, apart from running low on fluid, I can’t think of anything that will allow air into the system. Fluid out, yes, but air in - no.

Reading the OP's post again, another problem that could be causing the same symptoms is a binding/sticking brake. Pedal will be firm to start with but after driving for a while, the binding brake will cause the brake fluid to boil and result in a spongy pedal. It returns to normal when the brake cools down. I’ve had this myself along with a mate at the same time when we were coming down an extremely long, steep and twisty mountain road on our motorbikes in Italy and through fear and inexperience we were both dragging our rear brakes! Past: FL2 TD4 HSE Auto
Evoque SD4 Dynamic Lux Auto
Present: Audi A3 S Line.

Very interesting that Steve and correct as local indy who changed mine ( and also talking me through it ) said that something you had to make sure of was the springs being fitted correctly.


BTW what has your dog got all over him/her?  If it wasn't so bad it'd be funny.

🐑
Freelander 2 HSE auto 2014 ( Florrie ) ..... Try again.
Freelander 2 GS 2012...... Gone.