KB6 Clutch

Stop right there! You used grease??? You've contaminated the brake fluid.Take it back off and clean it very thoroughly again with brake clean 1st then denatured alcohol to remove any residue of the brake clean. That includes the reservoir before reassembly,which I would do by using a 1-1/2" rubber sink stopper in the bore,pour a some alc. in the top,screw the cap on and shake the hell out of it,empty and then do it at least twice more. Let everything air dry,denatured alc. evaporates quickly.
Use ONLY brake fluid to pre-lube during assembly.
Bench bleed the MC before installing.
Replace the steel brake line from the MC to the hydro-vac,it's very likely rusted inside,they're not expensive.

To answer the questions...
Yes,the brakes are "power assist", a Hydro-vac is a vacuum powered booster with a slave cylinder attached. That us why there's a specific procedure to bleed the system.

Hydro-boost is a combination of a vacuum booster & master cylinder,the function is very similar to an H-vac system but not exactly the same.

HydrA-boost brakes are powered by a hydraulic pump,such as a power steering pump and usually have a vacuum booster as "back up" in case the engine shuts off or the pump fails although some use a small electric motor as back up. Depending on the system a vehicles PS pump can be piped for both brakes and steering.
"Foundation brakes" are the wheel brakes to put it simply.
The plugged hole on the MC is for a brake light switch and should be 1/8-27 NPT.


Here's a couple 40's vintage (military) brake service manuals that cover the same type brake system you have.Very thorough,Read them!

https://ia700404.us.archive.org/28/item ... ed1944.pdf

https://ia601504.us.archive.org/3/items ... -1827B.pdf

They can be downloaded and then printed.

Thanks! I thought the HV was just the small front tube; now I see its the size of a basketball! We only used a tiny bit of clear grease on the outside of the seals only. About what a q-tip would hold.

Here is a pic of the front of my HV. I see now where the pipe from the MC enters. I have penetrating oil on it now.
[img][IMG]http://i91.photobucket.com/albums/k283/Halpics_bucket/003_zps273e6b5a.jpg[/img][/img]
Next pic shows what I found when I tried to trace the vacuum tube.......you can see that the 4" flexible tube has been accidently disconnected from a strange looking gizmo. Is this the vacuum source line for my HV?[img][IMG]http://i91.photobucket.com/albums/k283/Halpics_bucket/010_zps5ccf98a0.jpg[/img][/img]

Last pic shows wheel. When I bleed, do I loosen the lines right where they go into the wheel or are there special bleed bolts?[img][IMG]http://i91.photobucket.com/albums/k283/Halpics_bucket/006_zps6842cbce.jpg[/img][/img]

Thanks again for your help.

the funny gizmo where the vacuum lines meet is the vacuum two speed rear axle switch. you bleed the brakes with the little screw that sticks out right above where brakes line enters wheel cylinder, they can break REAL easy so go easy.

you really should take Scottso's advice and read up before proceeding so you have some idea what you are doing, you need to bench bleed master like Scottso said before putting it back in truck, do you know what that means? read the linked info. google bench bleeding master cylinder.

Will do. Now that I know how easy it is to take off the MC. If the pipes to the HVac are nice and shiny inside at both ends can I reuse them?

I assume I should hook up that vacuum hose to the junction with the gizmo or could it have been purposely disconnected like almost everything in the cab?

OK will bench bleed the MC. That's what my friend tried to do for me. But he forgot? to install a line from the outlet back to the reservoir. When in use is the line kept under the fluid level in the reservoir or can it just drop in from above?

Personally I'd concentrate on getting the brakes in working order before fretting over the 2spd axle control.
That 1st pic scares the begeeus outa me! Copper is not legal for hydraulic brakes lines and needs to be replaced with steel brake line.

I also see in that pic the H-vac unit appears to be a Bendix 3rd series single piston type.
I took the HV pic and boxed the bleeder locations.


The bleeders should always be on top @ 12 o'clock.


Here's the brake section of an IH service manual with more info on that type HV.
http://www.hansenwebdesign.com/truck/fi ... Brakes.pdf

Here's another manual I found,scroll about half way for 3rd series units.
http://dodgepilothouseclub.org/know/man ... brakes.pdf

I also forgot to mention that using a power/pressure bleeder is highly recommended when bleeding a hydrovac brake system.

All this reminded me,the unit may (likely) need "Lubricant" for the leather diaphragms (internal),the widely (suggested) lube used these days is NEETSFOOT oil.
https://www.google.com/?gws_rd=ssl#q=neatsfoot+oil

Not exactly sure on the amount needed but it's only a few ounces (2-4?).

Thanks. I'm not going to touch the HVac unless necessary. That's not copper tubing, just the rust soaked with penetrating oil. I hope to get the brakes working before the snow flies as I have no shop. Now I have to buy a flare nut to make my pipe for the bench bleeding operation after I disassemble and re-clean to MC.

I didn't say anything about "touching" the HV, all the info on them is for you to understand them and how they function.
You still have to bleed it first before doing the wheel brakes though. To be certain you'd have to check the info but,If I recall the control valve is bled 1st,then the slave valve and then the furthest wheel from the HV. Since it's on the pass. side that wheel would be the left rear. Make sure the wheel brakes are properly adjusted before bleeding.
Also,the HV is likely in need of more lube (Neetsfoot oil) if it sat for ??? Just remove the filler plug and use a finger to see if you feel any oil inside. If not add some.

Success! I followed Scotto's advice and took MC off, cleaned w/brake parts cleaner and alcohol, blew out, and did a 'bench bleed'. For that I bought a flare nut and flared a piece of copper tubing to return fluid to the reservoir. It worked great and after about a dozen strokes all the air was out and the fluid went up and down nicely in the reservoir strongly with each stroke (pic). [img][IMG]http://i91.photobucket.com/albums/k283/Halpics_bucket/002_zps5d6b03ce.jpg[/img][/img] Then I remounted it and took off the flare nut at the HVac. But when I worked the brake pedal the same old problem….no movement whatsoever of the fluid in the reservoir. WTF? So I remounted my homemade bench bleeder and got all the air out again, fastened the line back on and began pumping. Sure enough I finally got strong flow of clean fluid at the HVac. I hooked the line back in and now get good 'spouting' at the MC.

What is my next step? Where is the control valve?

The diagrams show the control valve deep inside the HVac. I need to take more pics to locate the place to bleed it. Would it be OK to only bleed at the slave valve?