Hot Rods Master Cylinder Covers - vented?

Why do some master cylinder covers have this opening? This is the cover I used for my under the floorboard master cylinder. Now it looks like there's water in the brake fluid - probably from driving in the rain (?). I've seen some comparable covers with no opening - just a solid cover. After I get rid of the water issue in the brake fluid, can I put a cover on with no opening?

 

There has to be a way for air to get on top of the rubber diaphragm to displace the fluid that leaves as the brakes wear, that’s why the diaphragms have bellows in them, the diaphragm is the seal not so much the cap, no you can not plug it


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Correct

 

Thanks for the info. When looking for a replacement I came across this photo which is listed as mine but I can see NO vent hole. That's what got me thinking (dangerous thing for me to do ) Any one else have moisture get in their cover/fluid this way?

 

I believe the two "dents" on the lid and the bump between the two are the venting system.

 

You can see a vent channel on the bottom right and top left of the picture, that little rib in the cover is the vent


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THANKS for your help. That looks like the cover I want to go with.

 

If your rubber bellows are installed right and not some how damaged water cannot get in the fluid.

 

Or air.

 

Which contains moisture.


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All brake fluid is hygroscopic which means it attracts and absorbs water. That is the reason depending on your climate and how hard you use the brakes, that periodic fluid changes are necessary.

 

Bob, I need some help with an intake can you reach out please 6023261408 Shawn