Brake Problem

[PassSPORT]

I just changed my Rear discs and pads today on each side, I then bled the brakes.
The problem is that when the engine is off you can hardly move the pedal at all, but when the engine is running it will sink to the floor in about 4 seconds. It really does feel like I am losing fluid, but I don't appear to be.
With the pedal being hard without the engine running, it doesn't make me think of air in the system?
I wish I had of tried the pedal before I changed the parts, but this is surely not normal?
Im crapping it now, any thoughts?

[snapdragon]

Maybe you damaged a front rubber brake hose and it is ballooning when the engine provides assistance. This happened to me and replacing the hoses at £12 a pop from ECP made the brakes feel better than at any time I remember. Very direct and firm and not spongy and soggy like they had been.

[PassSPORT]

Maybe you damaged a front rubber brake hose and it is ballooning when the engine provides assistance. This happened to me and replacing the hoses at £12 a pop from ECP made the brakes feel better than at any time I remember. Very direct and firm and not spongy and soggy like they had been.

It's just funny I noticed it after I did the work on the back. I never touched anything at the front. I am going to do the front discs and pads when I can get a dry day. I can understand the pedal traveling to a certain point, if the hose was ballooning, but it goes all the way to the floor like I am losing fluid?

[zollaf]

possibly, when pushing back the caliper pistons, if you didnt release the bleed nipple to let the fluid out, the master cylinder has not liked fluid being pushed back through it and a seal is now damaged. i have known this to happen. either that or there is still air in the system.

[PassSPORT]

possibly, when pushing back the caliper pistons, if you didnt release the bleed nipple to let the fluid out, the master cylinder has not liked fluid being pushed back through it and a seal is now damaged. i have known this to happen. either that or there is still air in the system.

I didn't do the bleed nipples pushing the piston back in.
How do I check the MC?

[peter cutmore]

I would try driving the car first as it happened to me and after a drive and a bit of gentle brakeing it came alright

[snapdragon]

How does the pedal feel if you already have the handbrake on 50-90%?
(in order to take up any mechanical play)
If it feels the same, it sounds like air in the system or damage, but most likely air.

Just buy some more fluid and try again, pour the new fluid in very slowly through the mesh bubble-catcher in the reservoir. Don't pour the fluid so that bubbles become entrained in the brake fluid as they stay in suspension and get carried down into the system. Obviously don't let the reservoir run dry either as this will take air down.

Pump the pedal slowly in long strokes using the weight of your leg allowing to sink down rather than be forced down. Some say only press the pedal down as far as it's normal travel as there can be an area of corrosion etc.. on the unused cylinder wall which can damage the seal. I makes sense, but I've never had a problem going down to the floor.

[Pit Dweller]

Is it a diesel? If so this is normal - If you had a fluid leak of any sort then it wouldnt matter if engine running or not - With the engine running servo vacuum is being created by the tandem fuel/vacuum pump - On all diesels the brake pedal sinks to the floor if pressure applied.

[PassSPORT]

Ok I'm getting real paranoid now.
Is it the norm when you press the pedal up and down, you hear an air escape sound???

Also, where is the MC located and how do I get access to it?

[snapdragon]

Ok I'm getting real paranoid now.
Is it the norm when you press the pedal up and down, you hear an air escape sound???

Mine made these funny noises like an artificial lung when the servo was water damaged by the plenum chamber flood.

My pedal used to sink nearly to the floor until I changed the front rubber brake hoses which were ballooning, so if anyone else has this problem, try replacing these, it is a cheap fix, especially if you are already working on the front brakes.