Classic/Antique Car Repair/Master cylinder

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Question
I have a 1940 Hudson 2 door sedan. The car has been sitting mostly for the past couple of years. I noticed about a year ago that the brake peddle was low to the floor so I checked the master cylinder and it was low on fluid. I filled the master cylinder and then bled the brakes. That brought the peddle  up to full position. I drove the car and the brakes seem fine.

I noticed the other day that the peddle is low again. There does not seem to be a leak I never see any liquid on the floor. Could the fluid be evaporating?

Thanks,

Marvin

Answer
Brake fluid is an alcohol base and as a result it will do two things. It will absorb moisture out of the air and become gummy and it will evaporate. Also after sitting for a while the rubbers on the wheel cylinders and the master cylinder will loose their seal with the cylinder bore and weep out fluid and let air into the system.  

Classic/Antique Car Repair

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Brad Sears

Expertise

All automotive including antique and collectible. However if the car has been modified I can only answer in general terms and maybe get you pointed in the right direction.

Experience

Automotive tech instructor. Syndicated auto columnist 1970's though the early 1990's. Syndicated auto radio talk show, Ask Brad About cars, CBS Radio 70's through 90's TV Show "Last Chance Garage" 1980's PBS-TV syndicated. Auto instructor for the following companies: Fram Autolyte Holly Carter AMF Ford Motor University Of Conn Blue Hills Technical School Sugar River Technical Center Grew up in a family garage in Needham Mass and turned wrenches from the age of 14.

Publications
Manchester Union Leader, Nashua Telegraph, Motor Service Magazine, Yankee Magazine, Popular Mechanics (Saturday Mechanic early 80's), Los Angeles Times, New York Times, and lots more.

Education/Credentials
More than I care to remember. Basically Franklin Technical Institute in Boston, Northeastern University, Fitchburg State Teachers College, Tufts University, and a lot of factory schools along the way.

Awards and Honors
Moto Award winner. And much more.

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