Losing small amounts of brake fluid

[hearn]

On a four hour trip (two there and two back) I lost about one to one and a half ounces of brake fluid in my 1954 Cadillac.  This is the first longer trip in a while so I could measure my loss.  Yet, the brakes seem fine: good pedal and no pulling to one side.  Any thoughts on where I might look first for the culprit?  Thanks, Jim

[signart]

First place I would look is the inside walls of your tires.

[tripwire]

Yup. If there is going to be a wet spot somewhere.  Look at the inner sides of your wheels, and at the hoses at the front wheels, the one hose on your differential and all along the frame where the pipes run.  You'll see it eventually. 

Wes in VT

[Steve Passmore]

Lift off the dust cap on your master cylinder and see if any fluid runs out.

[75DevilleFMBlue]

If you cannot find an external leak then you will want to start thinking internal leak. As in internal to the master cylinder. Masters can fail internally and when that happens they leak past the pistons and springs and leak into the booster assuming you have the comfort of power brakes, which I imagine you do. The easiest way I know of to check, which is pretty easy is to remove your dipstick from you crankcase (of fashion your own dipstick.) and make sure it is dry/ clean. Then remove your vacuum line from your booster and then slide the dipstick down inside your booster and pull it out. If it has fluid in the booster then that will be your culprit.

[Steve Passmore]

Sorry, I hadn't thought he could have a booster, So of coarse he will not have a dust cover.

[Jeff Rosansky CLC #28373]

I had trouble getting the line into the master and master cap to seal well in the 55.  I now have no visable brake fluid loss any more but still think I may lose a bit there. Mite be worth checking.
Jeff

[54cadillac]

54 brake booster is notorious for sucking brake fluid right thru and into the engine! Pull off the vacuum line to the engine and check for fluid. Do not drive the car if you find fluid there. Repair booster asap

[Mike Josephic CLC #3877]

I agree with several of the previous posters about
the Hydrovac.  If there is an internal leak, the vacuum
line to the manifold will be sucking brake fluid.

Remove the vacuum line at the manifold end and check
for brake fluid (use your finger) it will be wet if it's
leaking.

Solution:  Remove the Hydrovac for rebuild.

Mike