Brake Problems

Nearing the end of my rebuild with the MOT in less than 2 weeks after over a year of work. Having some trouble with the brakes. Without the vacuum hose connected to the servo the brakes are fine. As soon as the pipe is connected, the pressure will not hold in the pedal. I rebuilt the master cylinder using a kit for under a £5. I'm pretty sure the servo is working as it should and I've bled the brakes multiple times.

What could be the problem? Should I just bite the bullet and go for a new master cylinder?

youve either still got air in system or master cylinders poor , does fluid splash in reservoir when pedals pumped

I've tried bleeding all the air out but there are tiny bubbles coming out the front no matter how much I bleed. Haven't noticed any fluid splashing but all the pipes have been changed.

most likey m/c then if front lines and calipers are good

Changed master cylinder today. Same problem Looks like the MOT will have to be put off then

are rear brake shoes adjusted up ,are you still getting air bubbles in fluid when you bleed it

Make sure all the unions and joints are tight. Did you make up brake pipes and replace any?

I made up all the brake pipes and none of the unions seem to be leaking. I've bled them myself but need to do a final bleed with two people

use a piece of pipe in a jar and close nipple before letting pedal up open only to let pedal down,

it will probably pass a mot without the vacuum.. iirc it's only 40% efficiency

my 110 passed with one not attached.

you need a heavy foot and i would fix soon as mind

It's just it's half term next week and If I don't get it MOT'ed then, it'll be christmas before it gets done and Im taking my driving test on the 18th of November. It also needs to go for a VIC

You have not said if you have drums on the back ?

If it's the case it could be either that they are not adusted correcty as James says or that the shoes are in back to front and the adjusters are spinning in thin air !!

I am fighting the same battle.
Cannot get all the bubbles out no matter how many times I bleed it!

I have completely changed my entire brake system, everything.
Calipers, rubber and metal lines, 4 different master cylinders, brake booster and the valve thingy.
I have bled it dozens of times, I even bought a reverse bleeder. No luck!!

I have gotten used to the ****ty brakes now, as long as they don't get any worse. I don't know what else to try.

As 2 above have suggested, can you confirm the rear in terms of adjustment.
I went through ruddy everything....

And then adjusted my rear drum brakes.
Perfect now, bubbles to pedal feedback...

clamp each flexy off and see if pedal is mint, then release one at once to find where air is then try and address by then bleeding that corner or rear ,:rolly: