9 replies to this topic

[Mini_Matt]

Hi

I have a 1987 Mini Mayfair. I have the type 3 brake master cylinder with the yellow tag.

My problem is when trying to bleed my brakes I cannot bleed the back ones. The problem lies at the master cylinder...no fluid comes out of the lower hole of the master cylinder when i push the brake pedal.

I rad on this forum and found the suggestion to check at each junction whether there is any fluid but its not even coming out the master cylinder.

The front brakes have been bled so there is pressure in the top hole if that makes any difference.

I have also had the master cylinder off whilst I was doing an engine change and cleaning up the engine bay.

Please any suggestions.....Is my Master Cylinder knackered?

Matt.x

[Ethel]

How do you know nothing is coming out? where did you disconnect it to check?

Because the lower bore is bigger it creates less pressure than the upper, if you hook it up to the pressure regulator wrong it will cut off the flow from the lower outlet prematurely. Make sure the lower outlet is supplying the rear circuit, and bleed it first.

[Mini_Matt]

I removed the pipe at the master cylinder outlet. and there is no fluid coming out of the master cylinder.

The top is supplying the front brakes and the bottom is supplying the rear brakes.

I cant bleed the back brakes at all because the master cylinder doesnt push anything out.

[Mini_Matt]

Can anybody else give me any more suggestions on my query?

I need to no whether its the master cylinder before I buy a new one or whether there is anything else I can do...

Thankyou.

[lawnmowercrap]

Make a new brake pipe up that fits into the outlet on the master for the front brakes, and fold it in half, so its basically a piece of pipe sticking about 2 inches out that prevents any fluid going out of the outlet for the front brakes.
Then disconnect the pipe for the outlet for the rear brakes and press really hard on the brakes, see if you can clear the blockage.
If not, drain the fluid out and run compressed air through the outlet for the rear brakes gently and try the above procedure.
If that still doesnt work, you'll have to strip the master cylinder.
Im not trying to say you're stupid, but make sure you are refurring to the master cylinder and not the compensator mounted on the bulkhead.
Keep us posted

Lee

Edited by lawnmowercrap, 10 February 2011 - 11:27 PM.

[Mini_Matt]

Thankyou

I definately give that a go either tonight or tomorrow...

And its definately the master cylinder.

Cheers.

Matt

[Mini_Matt]

Ok...I did what you told me to do and..

When I pushed the brake pedal down hard it just spat a small bit of fluid out and did the same each time..
I used a compressor and its not blocked.

So do I need to buy a repair kit or something?

[Ethel]

It does sound like the master cylinder is faulty. To be sure, push the pedal to the floor and block off the outlet before you let it back up - that way you'll know it's not just drawing air in through the outlet, instead of more fluid from the reservoir.

[Mini_Matt]

Yep ive defo been doing it right..

Just bought a repair kit off mini spares.

[Mini_Matt]

Dont know if anyone is still reading this.

But I shall end on a high note. I took my Master cylinder a part and used this repair kit clicky
I have have never done this before and it was reasonably easy to do.

I fitted it back in the car and when I bled the brakes it worked fine, so there was obviously something wrong with the master cylinder.
So I'm happy now.

Edited by Mini_Matt, 21 February 2011 - 02:24 PM.