Pedal Goes Down To The Floor (89 Cti 1.6)

[lagonda 42]

Since getting my CTi back on the road, I've had trouble with the brakes. Have rebuilt front (Bendix) calipers & fitted braided front hoses, which has solved brakes staying on when warm....great!....but where before I needed to press the pedal twice to get a firm pedal, now it doesn't hold pressure at all, the pedal just goes down to the floor. You need to press quite hard to do that so the brakes work, but it couldn't cope with an emergency stop. If I pump the pedal it feels harder, but it still goes down to the floor.

I have (obviously!) bled the front brakes so am wondering if it's air needing bleeding fom the rear brakes ... but then if the fronts were OK surely the pedal should stop before it hits the floor? Otherwise what's the point of dual circuit brakes! There are no leaks from the system, so I'm wondering if I should suspect the master cylinder itself? Or would bleeding the whole system from rears to fronts do the job?

If it helps, with the engine off, pushing hard makes a noise from the master cylinder a bit like a miaow(!), sounds like fluid under pressure passing a restrction/valve. With engine running, the servo makes a fairly loud hissing sound.

Hopefully someone's had similar trouble & can point me in the right direction.

[Arahan 4]

Definatly the master cylinder, seals can be replaced AFAIK but I'd just replace with a new cylinder, there not expensive!

 

EDIT: Is there fluid on the brake servo? If so, 100% master cylinder!

Edited February 24, 2008 by Arahan

[lagonda 42]

Just checked & master cylinder is completely dry, does this mean it just needs complete bleeding?

[Arahan 4]

Pump the pedal then check the brake servo for fluid? It usually dribbles down it? Dont know what else it coulds be then! The hissing is the biggest hint at the master cylinder to me!

[lagonda 42]

Think it always has made hissing noise ... surely that would be the servo anyway, which seems to work OK? Have double checked the master cylinder & it's completely dry.

Laurence

[Simes 248 2 Cars]

Just checked & master cylinder is completely dry, does this mean it just needs complete bleeding?

 

Yes, as air will have probably got in to the system.

[lagonda 42]

Yes, as air will have probably got in to the system.

 

Sorry, you've taken me too literally, master cylinder is full, I meant the outside including the boot where the pedal pushrod goes, is all dry!

[lagonda 42]

Any more thoughts on this anyone?