Park brake leaking ?

[mikke60]

 Had this issue years ago, but don't remember the fix. When I apply the park brake,air is escaping from the master cylinder . Is the issue the P brake pull  or the master?
Thanks, mike

[buswarrior]

Where is air coming out? picture?
What kind of bus/parking brake system?

happy coaching!
buswarrior

[mikke60]

Ooops, this may help
1968 mci 5a

[Oonrahnjay]

Ooops, this may help
1968 mci 5a 

      But what kind of brake system?  In the past 4-5 decades, there have been two main braking systems, "DD3" and spring-parking/emergency brakes (we'll ignore my bus, which was built with a 4-foot long lever next to your knee and a steel rod the size of your middle finger running from under the driver's seat to the rear axle for a parking/emergency brake).  There wasn't a clean switch over between the two (generally, spring brakes were later) and some buses built with DD3's were modified and updated.  So you need to specify -- the way the park brakes works is different between the two.