KB6 Clutch

Yep,I see the nose of an H-vac too.
I found the thread I mentioned,on pg.2 I posted a ton of info/links. One has the proper bleeding procedure,follow that and see if you get a pedal. I have a hunch that will do the trick.
Also make sure you have good vacuum to the unit,run the engine a few minutes,shut it off and step on the pedal,you should hear a "whooshing" sound if the unit is getting and holding vacuum. There's should be enough for 2-3 times with the sound fading each time,after there's no vacuum left the pedal should be very hard.

Here's the thread link;
viewtopic.php?f=7&t=3273&hilit=hydrovac%2Chydrovac

Thanks. No leaks anywhere so I'll try and remove the master cylinder. How does a hydro-vac work? Is water involved?

How does a hydro-vac work? In the thread I linked to there's a YouTube video that's show's how an H-vac works. Is water involved? LOL No, the name is kind of a misnomer I suppose. You'd think it would be "hydrA" being it's hydraulic.

So watch the video,it will give you an idea of why a hydrovac must be bled 1st and in certain steps. Another link has troubleshooting,read all you find.

Thanks. Pretty discouraged here as I don't think I can get the master cylinder removed with my tools. All three bolts badly rusted. I don't dare heat too much because of the rubber boot. I can't even get a socket on the lower nut as the metal ring on the boot interferes. I can get an open end on it and a socket on the head, but I see the nut starting to round off when I apply a lot of pressure. My grinder will not fit in. A nut buster will not fit in. I have no air tool with chisel. I don't think I can get the fluid outlet pipe loosened either without ruining the small coupler nut. All I managed to do was get the linkage pin out and that took a long time as it was badly rusted also. Will I have to get a torch and burn off all the bolts in the entire clutch/brake pedal unit? Would a Dremel tool with cutoff wheel work? Sawzall?

I'm not familiar with KBs, but is the MC bolted to a bracket that's bolted to the frame that could be removed?

a new or rebuilt master is available & around $60 or less if you shop around, if yours is that bad on outside, inside is probably toast, you will probably need to replace steel lines as well, so don't be afraid to destroy the old ones,
buy your new master first, brake lines are available in all length and diameters at any auto or brake supply,

welcome to the world of old trucks, fun but a lot of work.

Gotta agree with Jon on the MC's condition and replace the lines.

I take it you have a Dremel tool and seem familiar with the cut-off wheels? I've used them since they came out for all kinds of things. They're great for small things and getting into tight spots,even more so with the flex shaft attached. I leave it on mine and hang it by a swivel clasp.
I've cut 3/8 bolts with no problem,just takes a bit longer than a 4-1/2" on a grinder.
I get the # 426 at Home Depot;
http://www.dremel.com/en-us/Accessories ... catid=2058

Here's the pn's for the MC by chassis number,yours should be the 2nd one.

K6 below K6 18518, KS6 12858, K7 32583,KS7 9465 + K6B,KS6B 501 up
48175H IH (w/o RCV)
MC661 Raybestos 1-1/2" bore
MC661 Wagner
Kit
121401HB IH <FC3622>
MK39 Raybestos
MK3622 Wagner


K/KB 6 ~ K6 18518 up, KS6 12858 up, K7 32583 up,KS7 9465 up
Master cyl. 1-1/2" bore
56509R91 IHC no RCV?
11120 Bendix
MC2657 Raybestos 1-1/2" bore
MC2652 Wagner
M2657 Dorman


Kit
64837R91 IH
MK135 Raybestos
MK8448 Wagner

Happy day! With help from a buddy we were able to get the MC off with no damage. Casting number is DH 27.2. Two days of penetrating oil might have helped. All interior parts look perfect. There is a small bit of corrosion, very shallow and a half inch wide, about 3/4 way to the bottom. The outlet fitting was partially clogged with rust. Could that have been the problem? What to do next? Hone and reassemble to test?

I'd at least rebuild kit it, cheap, & why put used plunger back in?

Scottso's numbers
Kit
64837R91 IH
MK135 Raybestos
MK8448 Wagner

The outlet being clogged with rust tells me the interior has rust in it too and as it's cast iron you'll never get rid of it all and that can cause issues later on. Also it may take more honing than you think to clean up the bore if it cleans up at all and the bore could end up being beyond tolerances. Not worth the time or effort really and the cost of the kit may be money wasted.

For the money the smart thing is a new MC.

I Googled the pn's...
Dorman;
https://www.google.com/?gws_rd=ssl#q=M2657+cylinder

Raybestos;
https://www.google.com/?gws_rd=ssl#q=MC ... er&start=0

Wagner;
https://www.google.com/?gws_rd=ssl#q=MC2652+cylinder

Best price I checked;
http://www.amazon.com/Dorman-M2657-Mast ... B001PYRHKG

You're dealing with brakes,not an area to take the cheap route with. Plus it's a truck and you have an accident it's almost always blamed on the truck. I've been driving big trucks as a profession for 25yrs. so I know the facts. It won't matter it being an antique,it's still a truck and that's all people will see (like someones lawyer).