406oc.co.uk

Hello all.i am new to this forum and I am having a real horrid time with my 406 brakes. The front pads where getting a bit low and the pedal was beggining to get a bit spongy so I replaced the front pads in the normal fashion, as i would any other car and used a g clamp to ease the pistons back and then i cleaned up the slider pins as one was corroded. I put it all back together, took it for a drive and the brakes where even worse. I gave them some stick but they did'nt get any better so i decided to bleed the brakes. I blead the brakes all round and after doing this I took it for a drive and they where even worse and I started to get a sinking pedal and having to 'pump' the brakes up between stopping. At this point I drove home slowly and blead the brakes again and this made no difference. Slighly confused I ordered a master cylinder ( New!) and fitted that the following weekend. I blead the brakes and it made absolutely no difference what so ever. Still convinced I had air in the system I did the two man bleeding thing and after seeing 2 litres of fluid go through it I took it for a drive and it was still the same.
When you bleed the brakes the pedal is quite firm - until you start the engine and the servo kicks in and the pedal sinks to the floor. After getting rid of the vacuum in the servo the pedal remains very springy. I also replaced the front flexi hoses and this made no difference.
I cannot see any leaks and no amount of bleeding makes any difference. I am hoping someone has had the same issue as me and knows what it is or I'm going to scrap the bloody thing!! It's been a great car BUT I have worked on loads of cars and never had this issue. I read in the manual that the ABS unit can need plugging in, in order to get it to bleed properly but I have no idea whay this would be necessary.

Help me please!

Hi there. Oh my god, that does sound rather scarey. Umm, you said you bled it the two man way the second time but how did you do it the first time? Are all 4 calipers free to slide (the rears can have some real issues), how about the rear hoses?

I've got no idea about getting air into the ABS block, although I'm guessing you can get air behind the return valves which are shut when the ABS isn't doing it's thing.

is the vacuum hose burst, split or loose?

if its diesel it could be the vacuum pump thing at the passenger side of the head.

If it was lack of vacuum wouldn't the pedal be hard not squishy?

Hi there - Thanks for your quick reply.
The first time i bled the brakes - before replacing the master cylinder I used a non return valve one man effort. After I changed the master cylinder I used the NRv method and then enlisted my mate and used the NRV too, in order to cover all bases. The vac hose is in situ and not split - I checked this and wandered if there was a valve in the pump that regulated the the vacuum. If it was stuck would I get too much vacuum? Is there one?
The rear brakes seem Ok to me. The pistons went back easily and the new pads fitted nicely. did'nt have any issues after the rears, it was later when I did the front pads the issues started. I have not checked the rear flexi's though I must admit. I shall have a look but squidgy pedal even after the servo is out of vacuum?
Anyone want to buy the thing off me? 1998, 2.1TD, GLX, Metallic blue, straight body and interior. Lots of new parts!

silly question, but i have often spent an evening trying to work out whats wrong with.

did you let the handbrake off when bleeding the brakes?

totaleclipse wrote:did you let the handbrake off when bleeding the brakes?

Doesn't matter - the handbrake's a set of cable-operated shoes under the disc and completely unrelated to the operation of the hydraulic brakes