master cylinder / fluid question

[p7387]

hello:
1987 305

i noticed that the smaller front reservoir is empty while the larger is full within range. i do not see a max/min marker line in the smaller reservoir. how much fluid should i put in the smaller reservoir?

also what is the proper way to insert the diaphragms after filling or checking?  by default they want to pop up neatly into the raised positions but when i open the reservoirs they seem sucked down and crumpled.

i suspect i might be loosing fluid  from the smaller front reservoir, i see no evidence of leaking so i would like to refill properly and observe.

thanks

[zieg85]

The small reservoir is for the rear brakes.  If you are loosing that you have a leak, either a rusted line or leaky wheel cylinders.

[zieg85]

The small reservoir is for the rear brakes.  If you are loosing that you have a leak, either a rusted line or leaky wheel cylinders.  Fill it up all the way to the top. 

[p7387]

thanks

where is the "max fill" location for the front reservoir and what about the diaphragm positions?

[Irish_Alley]

Its being sucked down from the vacuum of the master cylinder. Your leak ain't helping it since its letting fluid out and nothing is there to replace it. It will always suck it down just without a leak it won't be as bad

[p7387]

thank you

so whats a good "fill line" for the smaller reservoir and when reinstalling the diaphragms should they be installed in the popped up position?

still trying to pin point the leak

[Irish_Alley]

Look at your rear tires if you see fluid on the inside sidewall that's the leaky wheel cylinder. The rubber should go in so it looks smooth no creases like how a ball will look if you deflate it. The fill line should be flush with the other fluid. I want to say something like a 1/4" from the top of the separator

[p7387]

Thank you

Where is the "seperator" being referred to for level purposes?
The only position the diaphragm neatly locks into without any sloppy creases is its "raised elevated"position or the position where its not displacing fluid. So for clarification should the diaphragm be installed in the posioion where its displacing fluid or should it be installed in the position where its raised and let it suck down to its displacing fluid position during normal use?

[Irish_Alley]

the lips should rest on the edges while the lowest part is in the reservoir. if your displacing fluid you have too much in anyway. the separator is between the front and rear reservoirs

[p7387]

got it thanks

the diaphragm doesn't "neatly" "pop" into place in the lower displacing fluid position, it always has a stubborn seam that doesn't fall into place. dont know if that matters?

[Irish_Alley]

sometimes they will be right idk why, but i think the main thing is to make sure no air gets in. so as long as the edges are sealed you will be fine and it fits some what right. at least thats what i have always done

[diphthong]

Loosen your master and check to see if the fluid is draining into your power booster.