1946 Master cylinder problems

[yohoc1]

I think I know the answer but was wanting some opinions. I installed a 1946 Master cylinder on a Model A frame. I started pumping the brake pedal and I have fluid coming out of the top of small hole on master cylinder filler plug. I noticed the way I mounted the master cylinder that my brake lines are higher in some places than the top of the master cylinder?? Is this the problem?? And how would I remedy the problem? raise master cylinder? Thanks in advance.

[Terry,OH]

The master cylinder has an internal check valve that closes at a very low pressure so the lines can not drain back through the master cylinder and there is a very slight pressure in the lines when the pedal is not depressed. After applying the brakes and then releasing the high pressure in the brake lines returns back to the master cylinder through an orifice in the bottom of the fluid well just under the cap in a big hurry and without a cap will squirt out of the master cylinder. The bottom of the cap should have a shield to help prevent the fluid from reaching the breather hole.

[Mart]

In a standard ford application the master cylinder is not at the highest point so that is not your problem.
If you remove the filler cap and move the pedal, di you get a little blip of fluid under the area where the cap is, or a big squirt?
If you get a big squirt you might be able to adjust the length of the pushrod so you reduce the squirt to a small blip. You might also need to shim the piston travel with a washer.
It might be that you have excessive dead travel on the piston and the subsequently generated big squirt of fluid is overcoming the breather in the cap and causing the leak you describe.
Mart.

[yohoc1]

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Thanks for the info!!