3 replies to this topic

[NLinPEN]

Recently I removed the brake master cylinder from my car to fix a fluid leak between the reservoir and the cylinder. More about that can be found here: https://www.theminif...itment-problem/

 

After installing the master back in the car I am now having problems in bleeding the brakes. There is not much pressure on the brake pedal: I am able to push it to the floor. When bleeding the brakes I notice that fluid does come from the bleeders at the drums in the back. However, there is no fluid coming from the bleeders at the calipers in the front. Nothing, not a drop. Neither from the left, nor from the right hand side brake. Also, when undoing the bleeder there is no change in feeling on the brake pedal. When undoing one of the rear bleeders you can feel the brake pedal having less pressure. Not so with any of the front bleeders. I have tried bleeding the brakes with both engine off and engine on: makes no difference.

 

I am wondering what might be wrong, causing this to happen? Any hints or tips on how to proceed with this?

[sonscar]

Have you blocked the outlet from the reservoir,got an airlock?Open the pipe fitting that feeds the fronts at the master cylinder.Steve..

[Spider]

If you've used a rubber grease when assembling the Master Cylinder, this can block the very small transfer ports between the Reservoir and the Master Body. This is where I find a Bleed tool like the Gunsons particularly handy to get the fluid started. Once it starts to flow and wets up the inner of the Cylinder, it'll go like smoke.

[weef]

You will need to determine where the fault lies before you go any further.

Firstly, with the master cylinder resevoir full remove the two pipes that go to the braking system, with the brake pedal in the normal rest possition fluid should run from both ports if all is well with the master cylinder, if not check the master cylinder.

You can fit blanks or bleed nipples to the master cylinder, bleed it and check it works, i.e. the brake pedal should be pretty solid.

Once you have determined the master cylinder is OK connect up the car pipework to it and bleed the system.

You have given yourself a lot of grief by opening the bleed nipples at the wheels , you would have got away with bleeding the system at the first pipe union from the master cylinder.

Bleeding the brakes, in theory, is a straight forward procedure, but on thr Mini can prove tiresome and time consuming.

As suggested the use of a brake system bleeding tool, either a pressure or a vacumm unit is a big help.