Need help with hydrovac system 68 intl bus
I've got a 68 international bus that has soft brakes. If you pump them once or twice it does stop, I have had this bus a couple years and just now getting around to fooling with the brakes.
I did find out (from here) i needed a power bleeder, which i did pick up, and i found a guide on how to bleed them on the net.
It says to bleed the front hydrovac unit first, which i did, pulled a vacuum on the front bleeder (on the unit itself) and cracked the bleeder. I was able to pull a little air out of the system this all went fine.
When I got to the rear unit however, i pulled a vacuum and it held, then i opened the bleed screw. I got a significant amount of air out of the system however when I went to close the bleed screw it wouldn't tighten down. Off I go to a truck parts place that deals in heavy truck parts as well as napa and found a similar bleed screw with a slightly different taper.
It threaded in and tightened right down, however it does not want to hold much of a vacuum with the bleeder closed. I removed the new bleeder screw and checked and I can see a definite ring where it has seated down inside the unit so I feel like it is cutting off the flow of fluid.
After fiddling with it a bit I moved to the rear brakes they hold a vacuum with the screw closed and i was pulling some air from the rear lines... Mostly all air very little fluid from either rear drum.
Thoughts? Is my rear unit shot letting air in? Could the difference in taper be allowing air into the hydrovac unit?