Loadstar brake problem

Hi, hopefully someone here can help me with a brake problem on my 1969 L1600. After replacing 2 leaking wheel cylinders and vigilantly bleeding
the system, I have a pedal that goes nearly to the floor upon first actuation and then back to normal thereafter. Here is the kicker; when releasing the pedal fluid flows out of the tiny vent hole on the master cylinder cap. I had no problems with the master cylinder before the repair of the wheel cylinders. The master is the '3 bolt' type. Has anybody had this problem?

did you bleed the hydrovac? Most likely the problem is (if there is no air in the system) mis adjusted brakes. Heavy foundation type brakes need to be adjusted different then "car" floating shoe type brakes.
Get the manaul for the correct procedure, the shoe needs to be centered in the drum and most have two or more adjustments per wheel.
Follow the adjustement procedure in order and don't skip a step. Just because you hear the shoe barely rubbing doesn't mean it is adjusted properly.

My guess is brakes need adjustment, too.

Loadstar hydraulic brakes are Wagner and are floating.

Someone else had this issue awhile back and it was due to improper bleeding and even when done in correct order it persisted until a power bleeder was used. I don't think he's been back since(?).

Here's some links that should help...

http://www.bepco.biz/Catalogs/VacHydCat ... OOTING.pdf

http://www.bepco.biz/Catalogs/VacHydCat/BLEEDING.pdf

http://www.bepco.biz/Catalogs/VacHydCat ... LATION.pdf

Use only the info for a HYDRO-VAC brake system.

IH manuals;
https://app.box.com/shared/otkihx6yoa/1/61466349

https://app.box.com/shared/otkihx6yoa/1/37043126

That manual shows both 14" and 16", the 14's are and the 16's aren't. I'll trust Scott to decypher which ones you have. I do rememebr working on at least one Loadstar with anchor pin type brakes, which is why I mentioned it.

I just realized he didn't say front or rear.

FYI...
The 2 most common front brakes on a 1600 are 14 x 2-1/2 & 15 x 3 (depending on axle),with the shoes being "upper" & "lower" (both shoes are same) and adjusted with a cam and each shoe having it's own cylinder.
The common rear are 15 x 4,15 x 5 and 16 x 5 (depending on axle) with upper & lower cylinders and adjusters.
All in all there are 8 wheel cylinders on a 2 axle truck.Another reason to use a power bleeder IMO.

More info...
Going with the "'3 bolt' type" MC and presuming there is a hydrovac the brake code would be 04011 (wheel brakes use separate codes) the MC has a residual check valve.
There is a system with a "3 bolt" MC (different pn) that does not use a hydrovac but I don't think this one would have the issue of fluid flowing out the vent hole,would it?
It seems to me there could be air in the line between the H-vac and MC creating back pressure(?).

Hydrovac or not, it can flow back. If the shoes are out of adjustment, and he pumps the pedel, (so more fluid is in the line/cyl) when he lets off, all the fluid will be forced back out the bleed hole as the return spings acting on the shoes.the bleed hole is there to prevent pressure biuld up when the fluid heats up and expands.
In this case, air in the system or out of adjustment brakes result in the same outcome, more fluid is needed in the system, so it takes two application of the master, then when released, all that fluid has to come back, and it will vent out the top of the master res. This is especially true if the fluid is "topped up" while pumping or bleading.

Cornbinder's description is the same as my experience with the brakes on my L-160 with their frozen adjusters that hadn't turned since who-knows-when. Pretty sure those symptoms will disappear when I get my other axle with rebuilt brakes swapped in. When I replaced all the brake lines and refilled the system, with the engine off I'd pump the pedal three times and hear things moving inside the drums. Then after letting the pedal up, a few seconds later I could hear things move in one of the brakes and fluid would squirt out of the MC cap.