The Stovebolt Site Forums The Parking Lot Big Bolts best place to have hydro vac rebuilt?

im in texas but can ship anywhere, where do you guys send your hydro vac units to have them rebuilt?? and when will i know if it needs to be rebuilt???

when your brake fluid stars to disappear and you engine smokes, then is the time to have it rebuilt, the pneumatic chamber shouldn't have brake fluid in it, but if you take the big engine vacuum line off and it pours out brake fluid, one of your seals is bad, as for rebuilding, i bought a rebuild a few days ago and it has a sticker that says unit parts ,oklahoma city i dont know how old that sticker is, i cant find it on their web site

was it expensive for the rebuilt unit?

If you take it to your local NAPA shop, they have a place they send them to over on the East coast that rebuilds them.

There's this outfit out of CA that does rebuilds and can bore out & resleeve your wheel cyclenders: http://www.resleeve.com/booster.htm

BSC parts stocks all kinds of parts for the boosters and I believe they do rebuilds as well. Can write to thier tech peoples and see what they say: http://www.bscparts.com

Not up on what a rebuilt unit runs for, but they are still manufactured new for use on some machinery like forklifts and can be easily adapted to fit an old bolt. It's a matter of finding the proper piston dimensions for your truck. What I found when I was looking for one, a new unit will run upwards of $400.

AWSOME... just spoke to them in cali, i send my hydrovac to there they rebuild and repaint around 150.00 awsome

Had mine done at fleet pride in Cal about 3 years ago, was about 150$ seems like they did a good job. Best brakes of any antique I have ever had, I would like to know better in simple terms how they work though. I dont understand the hook up to the manifold and how it works and does not seem to affect the engines running ? just curious, I will have to read in my manual again, Tom.

Let us know how it turns out. I bought an old nos rebuild kit that was in great shape off ebay a year or so ago and still cant decide if I want to use it. The parts are in great shape though.

Jeff

Tom>
It looks more complicated than it is. the Hydrovac uses the vac port on the manifold to suck the air out of one side of the can. When you press the brakes there's a little piston in there that operates an air valve that lets outside air enter the vent tube on the opposite side of the can allowing the engine vac to draw the piston down. Piston is hooked to another piston in the small end that pushes your brake fluid.
Once you release the pedal the air valve closes and the pistons return to thier original position. The back brake pressure is released by a simple valve that opens when the piston bottoms out so you dont have dragging brakes.
It's very similar to some of the valves I work on in aircraft, hence why it's built by Bendix Aerospace.

Gentlemen...
All of the above are a good start.
BUT PLEASE DONT USE The dot 5 silicon fluid in your trucks,
ANY Leak in the vac side, however small, is sucked back into the engine.
And silicon/silica becomes SAND when burned ,
Dot 5 fluid is NOT compatible with MOST Brake part Rubbers And WILL DEGRADE it
PLEASE see the Tech Tips By Bob Adler on this.
Regards.
Steve Sr.

Freq, thanks for that info - I need it simple as possible if I am going to be able to grasp - and hang on to it ;-) Tom.