86 International Hydraulic Brakes

[hmacris]

I need a little help explaining the system/finding parts for my 86 International. The system was of the electric assist type, where the electric motor would provide boost when the bus was off in case the bus started rolling with the engine off.

My buddy blew out a brake line driving the bus around his property. Upon replacing the brake line and bleeding the caliper, the brakes were really stiff, which I first thought was good (thinking of my dad always liking a hard brake pedal) but then realized I was getting no brake action. I am assuming this has to do with the hydraulic engine driven pump, but the electric motor does not even come on now with the bus off.

Is the hydraulic pump independent of the power steering? I see a small fluid drip running down the steering column into the steering box (I think that is what it is).

Just trying to get a little background before I start ripping into things...

Thanks guys!

[Jive Turkey]

Did ya get'r fixed or figured out yet?

[martian]

The system is called Hydro Max, if you're looking for info. Uses a 2" bore master cylinder. Similar to the Hydroboost on Chevy trucks, just much beefier. From my understanding the backup motor will run until pressure is built up. If there is a leak, it will run continually. For how long I don't know. Mine wasn't building pressure, and going through a lot of brake (break for the illiterate) fluid. Ah, yes, someone left the left rear brake nipple open. Once I snugged that, the boost motor stopped running. Parts are readily available, either the master cylinder or booster. Not cheap though.