hydraulic brake pressure tester

[Bonham]

Hello, I need to check the Hydraulic brake pressure throughout this old 1959 B600 school bus I inherited. I have to pump three times to get a solid pedal. It holds at that point but I dont feel safe. Need to see if its the master cylinder or HydroVac booster component or just air in line that I cant seem to get out.
Any recommendations on a kit that measures brake pressure? bleeders in back are 7/16 24, front are 3/8 24. I saw one on Amazon for 90$. I already purchased a gauge but struggling getting the interface connections. should have 966 PSI in to system.
thanks

[basketcase0302]

"Bonham"Hello, I need to check the Hydraulic brake pressure throughout this old 1959 B600 school bus I inherited. I have to pump three times to get a solid pedal. It holds at that point but I dont feel safe. Need to see if its the master cylinder or HydroVac booster component or just air in line that I cant seem to get out.
Any recommendations on a kit that measures brake pressure? bleeders in back are 7/16 24, front are 3/8 24. I saw one on Amazon for 90$. I already purchased a gauge but struggling getting the interface connections. should have 966 PSI in to system.
thanks

99% of us here have never owned such a tool, (be advised that brake pressure is like hydraulic pressure and dangerous to play with) coming from a USN Machinist mate who worked with 4K pound hydraulics on a nuke sub.

Your usually gonna find a wet spot where the fluid is leaking, (or you've got air in the system and need to do a good bleed on it).
Look into a Mityvac tool to properly bleed if you don't have a 2nd set of hands to help you, (always been my case).

[Bonham]

Thanks for the tips. Ill see what I can come up with.

[fastEdsel]

Try this site, on there it shows a schematic of the hydrovac and a detailed account of how to bleed these systems. Ford-Trucks.com

[tsherry]

I have a 71 F-500 with a front/rear master cylinder an the vac booster under the cab. If the truck sits for a prolonged period of time fluid will bleed out of the master and the pedal will go to the floor, like the MC is bypassing. I assume the fluid goes into the vac booster (both have been replaced) and leaks out of the truck. There is no leakage at the eight wheel cylinders, all were replaced, nor any evidence at the booster. Once I refill the booster, I'll cycle the pedal a few times, and in an hour, I have full brakes again with no pumping the MC up.

Been like that for fifteen years. Full brake rebuild 18 months ago to the tune of $1400. I'm not equipped to lift such a beast off the ground, so I found an independent heavy truck mechanic--did the work in about a week. The mechanics traded off working on it, as they liked it so much. "So easy to work on!"

[1972hiboy]

[quote="Bonham"]Hello, I need to check the Hydraulic brake pressure throughout this old 1959 B600 school bus I inherited. I have to pump three times to get a solid pedal. It holds at that point but I dont feel safe. Need to see if its the master cylinder or HydroVac booster component or just air in line that I cant seem to get out.
Any recommendations on a kit that measures brake pressure? bleeders in back are 7/16 24, front are 3/8 24. I saw one on Amazon for 90$. I already purchased a gauge but struggling getting the interface connections. should have 966 PSI in to system.
thanks[/quot


If this is something that has been sitting for a good long while I would plan on replacing wheel cylinders. If they are stuck you could still get a hard pedal but have reduced braking affect. then re-bleed and retest.

[tsherry]

"If this is something that has been sitting for a good long while I would plan on replacing wheel cylinders. If they are stuck you could still get a hard pedal but have reduced braking affect. then re-bleed and retest."

Exactly right. I had a good hard pedal on a '37 Packard that had been sitting for a decade inside a conditioned storage facility. When I pulled the brakes apart, I had 2 pistons out of the eight in the wheel cylinders that moved. The rest were seized and all the cylinders had fluid in addition to crystallized fluid, rust, and water.

Cylinders are cheap. Lawsuits and hospitals, not so much.