1949 F-1 Master cylinder-NAPA

[Redhorse1947]

I picked up a NAPA master cylinder and notice quite a difference (at least to me) from the original. As you can see from the picture only the smaller brass cap (vented) can be removed. The larger black metal cap is VERY tight and has the "tamper" markers which indicate if the black cap is removed. I assume this is for warranty. Anyway, when you look into the hole that can be viewed with the brass cap removed there is something directly below the fill cap.
WHAT is inside this cylinder that blocks the ability to see the volume of brake fluid and if fluid needs to be added?
I will be going back to NAPA (different town) Thursday for other parts and will also question them but thought others may have crossed this bridge and can give me some thoughts.
Thanks!

[V8 Bob]

Originally Posted by Redhorse1947

....Anyway, when you look into the hole that can be viewed with the brass cap removed there is something directly below the fill cap.
WHAT is inside this cylinder that blocks the ability to see the volume of brake fluid and if fluid needs to be added?.....Thanks!

It may be retro-fit diaphragm/gasket that prevents air from entering the fluid, like later masters have had, and all should have.
Maybe it's time to switch to a dual master.

[51 MERC-CT]

If you have not put fluid in it, how do you know that you can't see the level??

[Ross F-1]

Almost sounds like a connection for a remote reservoir hose?

[JSeery]

There was a very similar post within the past week on the same topic, might see if you can find it and see if anything was resolved.

[TJ]

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Glad you brought this up. I just bought one from Napa for my '41 pickup with the same cap. The fill cap is an inverted flare plug. I have all the same questions. Keep us posted.

[donald1950]

it looks to me that it is for a remote resevor... just a guess.....

[V12Bill]

A couple of years ago I bought a MC for my '39 PU and I asked if it was USA made. They assured me that it was and ordered it for delivery the next day. When it arrived, it was marked made in China. I refused to take delivery and they charged me 10% restocking fee. I was not a happy camper. Maybe your MC was made off shore.

[51504bat]

Originally Posted by V12Bill

A couple of years ago I bought a MC for my '39 PU and I asked if it was USA made. They assured me that it was and ordered it for delivery the next day. When it arrived, it was marked made in China. I refused to take delivery and they charged me 10% restocking fee. I was not a happy camper. Maybe your MC was made off shore.

When I purchased my '39 p/u the PO had installed a new off shore m/c and it would not release properly causing the brakes to stay engaged. Ordered a new USA made Wagner m/c from Joe's and no more issues.

[tanner]

I just installed the same NAPA master cylinder on my 49 F1 and I took the larger (square black) cap off so I could bench bleed it and then see the fluid level as I bled the new lines I have also just installed. I have a full firm pedal and brake are working fine. I had originally purchased a Wagner m/c from NPD only to find it was $40 more and make in Taiwan so I returned it in favor of the one from NAPA.

[RandyZ]

These master cylinders are also used in some brand of fork lift, so the parts guy told me. Maybe on fork lifts there is a access problem, so they use a remote filler?