Re: Master cyl. bleeding

Posted by BH On 2009/8/12 7:54:29

I have never bled a TreadleVac master cylinder, itself.

Take a look at the cross-section shown in the Brakes section of the factory shop manual. Notice that the compensator port is open when the pedal is in the released position. My feeling is that this particular master cylinder is, for the most part, self bleeding - just fill it up and wait a little.

Now, I will admit that there could be some air trapped in the passage leading to the outlet port even after the unit is installed in its angled orientation in the Packards, but that doesn't merit "bench bleeding", IMHO. In-car, one could loosen one of the two nuts on the outlet fitting just enough and have some one push the pedal to burp it, but even that seems like overkill.

I'm gonna be bleeding the wheel cylinders and wanna push all that old fluid out, anyway.

I use a MityVac handheld vacuum pump with their bleeder attachment to catch the spent fluid, but stop and top off the m/c reservoir periodically. I start with the wheel closest to the m/c and work out from there, but make second a pass around the car. Sequence is more critical with tandem systems' especially when diagonally split - even moreso when ABS comes into play.