smaller brake reservoir empty

[p7387]

hope this is the correct spot on the forum for brake related issues?

1987 305 2WD short fleet
the front/small brake reservoir keeps depleting completely, in addition the rubber bladder is always partially getting sucked off of the square perimeter of the reservoir itself, is this normal because it never seats nice?

this small reservoir is specifically for the rear brakes correct?
i do not see any obvious signs of leaking, i need to get under the truck and look at the lines

any advice ?
thanks

[zieg85]

If it leaks down slowly it is more than likely one or both of your rear wheel cylinders is seeping.  Yes the small reservoir is for the rear only.  I have also seen the master leak back into the inside of the cab with no power brake set up.

[Irish_Alley]

If it leaks down slowly it is more than likely one or both of your rear wheel cylinders is seeping.  Yes the small reservoir is for the rear only.  I have also seen the master leak back into the inside of the cab with no power brake set up.

if it was a line problem it would be a sudden lost of brakes so it should be a slow leak. the rubber is supposed to seal but if you are losing fluid the lack of fluid in the reservoir will cause a vacuum and suck the rubber down. 

[p7387]

sorry i see i accidentally posted this in the "truck of the month section"
perhaps it will be moved to the appropriate section

if i fill it and drive for just a short while its already empty, and the brakes seem slightly off.
i don't see any obvious leaks but i need to check further

[Jason S]

Pull the rear drums off and take a peak inside.

[pneuner750]

Is this manual transmission ?  If so it's  your hydraulic clutch.

Sent from my SM-G900V using Tapatalk

[Irish_Alley]

if the wheel cylinders leak they will drip down the rear tires on the inside. you will normally see dirt stuck to the bottom of the backing plate on the inside of the drum