All Brake fluid disappeared from the brake reservoir

1968 semi auto beetle only driven a few klms a week in the summer.
My brake pedal started to go down to the floor although the car still stopped as normal. It had been passed for rego only a couple of months ago. When I did check the brake pedal I found it was indeed going to the floor. I then checked the brake fluid reservoir and it was dry. Put a finger in it all around and it was bone dry... I refilled with brake fluid and the level stayed the same. I can't find any traces of where the fluid went to. After a couple of weeks I drove it and I had to pump the brakes to get the car to stop. the Level of fluid still the same. I bled the rear brakes [about 100mls each] and no bubbles in the fluid. The brake pedal is now back to normal but I haven't driven it as yet. I suppose the next thing is to take the master cylinder off and put a kit thu it.
Anyone ever have this sort of odd problem???

Lee

If it is only a few km weekly, and only a few 100mL, then it could still be sitting in the drums from the slave cylinders, or weeping out a pinhole in the flex lines, or ..........(you get the idea), and there may not be much or any indication of anything amiss.
If the fluid isn't on the ground but drained somewhere that's my 1st guess.
Whatever it is though a proper service and inspection should find it OK.

If there is no sign of fluid near any of the wheels- check the carpet and floor under the pedals.

nbturbo wrote:If there is no sign of fluid near any of the wheels- check the carpet and floor under the pedals.

second this. thats where mine was

or in the bulkhead gap section

have a look under the pan the fluid will seep through the seams

Ours is a type 3 so a bit different. Found the line from the remote reservoir to the master cylinder had decided to weep where the steel line went int rubber for a bend. Was going to replace it but after wigging it around trying to work out the size it sealed itself up. Now I've got a piece of spare rubber hose in the toolbox for when it decides to do it again.
Our super beetle has a patch on the floor that looks like there has been a fluid leak on it. That will get fixed when the car gets ready to run.