I have a Napa P 2080 68-75 F-250 or 350 master cylinder that is leaking out the direct bottom. In the center of the casting there is a bolt of some sort that when pulled out does not let all of the fluid escape yet does have a rubber O-ring.

Any ideas on what this might be, direct center, directly underneath on bottom Any ideas on why it might be doing this would maybe be helpful as well, thanks

 

that bolt i believe is the stop for the secondary piston.

 

Maybe this will help, if it is the ..........stop for the secondary piston...........that why would it be leaking, I see alot of masters do not even have this so why it it there?


New master, not reconditioned

 

Well I was wrong, Napa gave me a remanuf. master cylinder according to the pictures on their website, the new one does not carry this bolt at the bottom

Here is the new


And here is the remanufactured



I am hoping to have my questions still answered, I need to do something with this first thing in the morning, thanks

 

Not sure what your question is then. I thought you wanted to know what the bolt was for. This exploded view-even though its a nissan master cylinder shows that it is a stop for the secondary piston. If your is leaking, youll need to install a new copper washer or o-ring on the bolt. I dont suggest you pull out the bolt unless you depress the brake pedal a bit. You risk nicking the piston as the bolt is withdrawn. M/C are pretty cheap these days. Id replace it for piece of mind
Tech Wiki - Tokico Brake Master Cylinder Part Numbers : Datsun 1200 Club

 

Thanks, you mentioned in your first post that you believed it was the stop, I posted a picture to try and can confirm this, I also wanted to know whats its function was, why it might be leaking, as I mentioned it is a new master.

I am going to replace it this A.M with the new version without the bolt, thanks for the info though, at least I know what it probably is although I still dont know what it does and why two master cylinders that carry the same part #s and same applications are different in this sense.