How can you tell if there is air in the master cylinder?

I installed SS braided lines and ATE fluid yesterday ... in that order. During the line replacement, fluid drains out of the hard chassis lines. I figured it wouldn't be enough to empty the reservoir but when I returned to the engine compartment I noticed just a little bit of fluid remaining in the reservoir. Because it is opaque and you cannot see down through the top I was not able to tell if there truly was no more fluid in it.

 

I immediately filled it with ATE and began the system flush. I have not yet flushed the ABS pump with the gravel road method (getting the ABS to turn on and cycle fluid). I will do so once I can be certain that there is no air in the m/c and then do a complete system flush again.

 

I must note that the pedal feel is exponentially better, catching right at the top. I have not yet driven spiritedly yet, but there is a significant difference with even casual driving. Thumbs up to SS lines.

 

I have read the vaction pix on bleeding the master and it seems that they make it seem easier than it truly is.

 

Is there any telltale way to know if there is any air in the master cyliner?

yes, your pedal would drop and you would have no pedal feel to begin with. As long as you dont suck a tiny air bubble into the hard lines and into the rest of the system, you're fine. I normally fill my fluid to the top as indicated on the brake resevoir. As your brake pads start to wear down, so will your brake fluid, which I normally keep topping it off to ensure that my fluid isnt so low to where it would end up sucking in air because there's no more fluid left.

The master proves he's worthy of his title once again ... thank you