master cylinder

[meganwilkinson2008]

Hi
Can anyone help me i have a 1969 traveller. The problem i have is if i fill the master cylinder more than half an inch from the bottom when you put the top on and apply the brake it seeps fluid through the little hole in the top.Is this correct or should it be filled right to the top ?. All the brakes are new and seem to work fine. Any advice would be most appreciated
Thanks john .

[bmcecosse]

There is always a little 'fountain' of fluid. Sounds excessive if it's coming out the breather hole. The reservoir would normally be filled to 'near' the top - just a small air space left clear.

[meganwilkinson2008]

Many thanks for reply will try it filled near to top like you said have only done it half way before maybe its that that is causing it to fountain.thanks again.

[jaekl]

The fountain is caused be returning fluid with the help of the springs on the brake shoes. An excessively high fountain is an indication of air in the line. Does your MC cap have a brass plate on the underside? It shields the vent hole from direct spray.

[bmcecosse]

I don't agree that it indicates 'air' - at all!

[don58van]

Just last week I overhauled my MC.

When I refilled the MC and pumped the pedal, the reaction in the reservoir went through various stages as the air was expelled. At first there was no real pedal resistance from the MC, but it gradually built up with repeated pumping as air bubbles emerged from the reservoir.

At one stage during the process, when I pumped the pedal (not particularly fast) I got an substantial fountain that squirted across the front passenger compartment. Fortunately, I had all the carpet out.

Hence, I pumped the pedal more gently for a while and the fountain effect subsided.

Finally, I bled the brakes and got a really hard and consistent pedal and little or no fountain effect.

So, make of that what you will. To me, there seemed to be a stage where conditions produced a disproportionate squirt from the reservoir.

Cheers
Don

[meganwilkinson2008]

Many thanks for all the comments.I dont have a brass shield under cap you can see right to the top where you can see two little breather holes.Have now tried MC full up but it still seeps fluid through breather hole.Have spoken to charles wares today and they say should be filled just over half way. Will have a look to see if i can get a new cap to see if there is anything different.

[chesney]

Just out of interest, does it have a servo fitted? My partner's Minor has the rear outlet plugged on the cylinder, so has some strange side effects such as this!

[meganwilkinson2008]

No it has all standard brakes pedal is high and firm,up till now only way i can stop it seeping is to lower the level down in the MC.That was interesting about a shield under the cap may mig a blank in just to deflect the fountain but still allowing it to breath.Its all a bit odd. thanks again

[meganwilkinson2008]

Finally got the MC sorted welded a blank about 1/4 inch drop from bottom of cap on a steel stem. Now works perfect even if you hit the pedal very quick,no seeping at all, it just stops it spraying up the cap.many thanks to all for very useful info.

[bmcecosse]

Charles Ware... the 'experts'.... There was something wrong with your cap then - because they 'all' have a false base in the cap.