Lancia Motor Club

Hi, I have bought a refurbished brake master cylinder from Italy, and am having trouble obtaining brake pedal pressure. I have bled all the brakes and have clean fluid and no bubbles but there is still no brake pressure. There are no leaks either from anywhere.
The pedal still goes to the floor but with very very slight resistance.
Any ideas? Could there be a fault with the seals inside the master cylinder?

M

Some suggest filling the master cylinder with brake fluid whilst 'on the bench' before fitting to the car, which you may already know.

Hi Richard, I did not know that. What benefit does this give?

A master cylinder primed with fluid it would seem

Same thing happened to me some years back. Graham Bates, who was working on it, spoke to someone who advised him to assemble it 'wet', i.e. with some brake fluid in it and the problem was solved. So long ago that I can't remember if the seals had been damaged in the dry cylinder or whether they were reused. Apologies if I'm I'm telling you something you know but there is also the unusual bleeding sequence of upper fronts, lower fronts, then rears.

You shuld be able to prime the master cylinder by cracking open the pipe union until fluid comes out.

Cheers All, I will try the prime tonight.
Best regards
M

Hi All, I bought a Sealey brake bleed kit to try a pressurized bleed but it was not successful. The vacuum drew the fluid through but it was a continuous stream of fluid and bubbles that did not reduce in air content after some minutes and a lot of fluid.
I had the master cylinder off as well and it was not leaking and seemed to fire fluid out when manually pressed in.
What does this now indicate? Do I have an air leek in the system, but if so, why is there not a pool of brake fluid under the car??

Any ideas?
M

I know it is a typo and I often do them myself but the thought of an "air leek" in the system has just brightened my morning and I am not even Welsh.      I use pressure from the top to bleed my car brakes (Eezibleed) but use pressure from below to bleed my motorcycle front brakes.   It might be worth a try, air rises after all and can be trapped in loops.    Just force fluid into the bleed nipple with a suitable syringe (beg a bladder syringe from your district nurse).

Presumably the vacuum device is fitted with a flexible pipe over the bleed nipple. I have no experience of using such a system, but my experience of bleed nipples is that often when you open them up fluid also leaks out past the threads of the bleed screw. My guess is that air would get into the system at this point in just the same way. However, having now got some fluid into the system then conventional bleeding using the brake pedal might do the trick.

Colin

quite right Colin, I have one somewhere and choose not to use it for this very reason, it works well but is very deceptive because of all the air bubbles, however they are coming into the system outside of the system if you get what I meen so wont put air into the caliper, the most success I've had with bleeding brakes is just to use gravity to bleed it, crack the pipes off nearest the master cylinder and keep working back until just fluid runs out, the Augusta has pitting in its master cylinder where the seals don't normally run, however when trying to bleed conventionally the pitting allows air into the system , took me ages to bleed the brakes until my father suggested the gravity bleed theory which worked perfectly on every vehicle since

Will the 'gravity only' routine work where, say. on our Fulvia GTE with a remote servo, there are parts of pipework which sit slightly higher than the master cylinder. Will the gravity method carry the air in these high parts through in time or will it just stay there?
I always prime the master cylinder on S1 Fulvias before bleeding  by the way
Chris

On GTEs and Rallye S cars, brake bleeding should be done with the engine running so that the remote servo (assuming it is working ok) will help pushing fluid in the system. Andrea

Also the rear axle mounted bias valve (if fitted) should be in the open position, ie not with the rear suspension on full droop.

The rear brake bias valve on our GTE has its own bleed nipple which I find particularly difficult to get to as it is mounted up above the rear of the front subframe. My hands are too big to get to the bleed nipple easily from above or below even if I remove the detachable rear crossmember of the subframe.
When I first bled the brakes on the GTE I didn't even know that there was a rear bias valve with a nipple fitted as it doesnt seem to appear in any Lancia literature or diagrams I have for the car. Martin Cliffe mentioned it to me when we were discussing the GTE braking system on the telephone and that was the first I knew of its existence!
I am also somewhat surprised that the remote servo doesn't have its own bleed nipple. In the dim and distant past we had a 1.3S Coupe with remote servo and I thought I remembered that the servo on that car had its own bleed nipple? Could I have been correct?
And finally, I didn't know that the engine should be running on the GTE for brake bleeding because of the remote servo - thanks Andrea...obvious when I think about it.
Chris

Hi Chris,

I never had the need to touch the limiter valve on my GTE although I do replace brake fluid every 2 years. With the engine running, everything is much easier (no bleed nipples on the servo, at least on the two I had on my car-one original and kaput- and the new one). The servo is the same as on standard Alfa Romeo Giulias of the late 60s.
On S2 Fulvias I agree that it is essential to jack up the rear axle to fully open the limiter valve. Cheers, Andrea

The brake master cylinder seems to be faulty as 2 garages later and all the techniques known to man, there is no pressure. The fluid must be passing over the seals. They have been changed for a new set as well!

So, has anyone a used one that I can try with new seals?

M

Omicron do a bore polish, reseal and bench test service on your own m/cylinder.
I haven't used it (yet) but Martin assures me it works!
Chris

Persevere with bleeding.. Try gravity alone at the back first. It takes a long time. I assist with a little (2psi) pressure at the fluid filler on the master cyl. Keep an eye on topping up fluid. When the backs show fluid ,do the fronts. Are you sure the internals of the m/c are correctly assembled and the valving is not gummed up?