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Disappearing Brake Fluid

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kyreb1862

kyreb1862

Jedi Knight
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A couple of times now I have had to top off my master cylinder on my 77 B. I have replaced most of my brake components such as flex lines, wheels cylinders, pads and shoes. I can't observe any fluid leaking from the drums or calipers. The brake pedal feels good and there are no leaks around the master cylinder. I don't think I have my brakes adjusted right so is there a possibility that the pistons in the wheel cylinders have pushed out? How could I tell if fluid was getting sucked out through the brake booster? /ubbthreads/images/graemlins/confused.gif
 
Brake fluid sucked through the booster will find its way into the combustion chamber. You will then emit a rather dense, whitish fog reminiscent of a James Bond flick.

I had this happen to me with one of my MGCs. A rebuild of the booster(s) took care of the problem.

(Not saying that this is the root of your problem...just one of the possibilities.)
 
[ QUOTE ]
Brake fluid sucked through the booster will find its way into the combustion chamber. You will then emit a rather dense, whitish fog reminiscent of a James Bond flick.



[/ QUOTE ]

Ok, that clears up that question, because I have never seen any evidence of burning.
 
You may still want to pull the big vacuum line that goes from the servoe to the check valve on the manifold and check it for any signs of brake fluid.
 
Did you actually pull the drums to see if the cylinders are leaking? How much fluid are you losing? The level will drop a little as the pads wear.
 
No I haven't actually pulled the drums yet. I have only put about 100 miles on the car since I've done all the work.
 
If you've no evidence of external fluid leaking and the M/C level is dropping in 100 miles, the only place it could be going is that funky servo unit.
 
You won't generally see the "white smokes" right away as the servo has to fill to the level of the vacuum feed line where it joins the can, and then be slowly sucked up into the intake manifold. I'm not saying this is def. the case, but you should check. You may have to make yourself a little "dipstick" to probe down to the lowest point of the servo can. Good luck.

Motorbill
 
Yup. Coathanger or suchlike works... be SURE to put a tight, smooth loop on the end or risk diaphragm puncture... The "kit" includes the diaphragm, and it should be replaced anyway but you may want the brakes still working before you do the job, IYSWIM. /ubbthreads/images/graemlins/wink.gif
 
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