Itinerant Air-Cooled

Fluid is good. Recent flush, and in between Min and Max level.
My brakes are intermittently started working poorly, and there is a little pool on the bottom lip of the booster. I was driving, and as I tried to slow down, the brakes got really soft, "the swoooft" sound came from under the dash, and the brake light came on, flickered and went off.. I immediately released the brake and pressed it again, and it was firm again, but it could still get past the firmness if I press too hard. I've been driving the F250 too much, and it requires serious force to be applied for stoppage. I blame it on myself. What could be wrong?

luftvagon wrote:Fluid is good. Recent flush, and in between Min and Max level.
My brakes are intermittently started working poorly, and there is a little pool on the bottom lip of the booster. I was driving, and as I tried to slow down, the brakes got really soft, "the swoooft" sound came from under the dash, and the brake light came on, flickered and went off.. I immediately released the brake and pressed it again, and it was firm again, but it could still get past the firmness if I press too hard. I've been driving the F250 too much, and it requires serious force to be applied for stoppage. I blame it on myself. What could be wrong?

Master cylinder seal failure. Often happens after a flush.
Colin
(replace with best available)

seal or the master cylinder :)

luftvagon wrote:seal or the master cylinder :)

All the damn seals INSIDE of the master cylinder. You are shoving a piston down a bore with as much leakage as a french press coffee maker.
Get the best master cylinder! assembly! as you can.
Colin

Another interesting observation. With engine not running/no vacuum provided to the booster. The master cylinder appears to work fine. How involved is the replacement? The whole dash needs to come down? Any objections to Napa Master Cyl and/or brake booster if needed?

Do NOT use the napa replacement. Use FAG/FAE or Varga. And use FAE switches.

When you do the replacement, make sure to adjust up those rear brakes really tight, as in it takes a some effort to turn the wheel all the way around, but it doesn't totally bind anywhere. Vanagons like really tight rear brakes, keeps there from being too much travel in the master and wearing out the seals and pistons. You'll notice much better pedal response too.

Double check your clutch master feed line while you are in there, much easy to replace a cracked or wrong-hosed one (blue viton, not some old fuel line hose) now instead of having to spill brake fluid everywhere again sometime soon.

Where can one find these replacements?

And:
For type2 - what to use for the hose between reservoirs? Beetle blue line? The original seems fatter at the reservoir nipple, but maybe that's just age.

I found the ATE/FAG Master Cylinder, and will put in an order tonight. Should I worry about the booster also? What else should I replace? The switch?

If your switches are good, and/or you can't easily acquire FAE switches, just swap them over with a little teflon on the threads. If the engine isn't stalling when you brake, the booster is probably ok, just try to clean it out if it has any brake fluid in it. If Les Schwab has ever done the brakes, you'll likely have to take the drums off and flip over the upper springs that they love to install upside down, blocking the movement of the adjuster stars...

Hammy, the buses took that special plastic line, which is unobtainium, save for stashed used ones. The lines usually don't go bad, just the little rubber boots that go over the nipples on the reservoirs, and slip inside the "fat" ends of the plastic line, like a little brake fluid condom. Those are still made from obtainium. But if it does crack or what have you, I'd say maybe some of that viton hose they use for bio-diesel retrofits?

Parts ordered, and will be delivered this week... While there, I opted to go ahead and completely rebuild my brakes, and my clutch master, and slave...

Front Brake Pads
Rear Shoes
Shoe Hardware Kit
Brake Master Cyl
Clutch Master Cyl
Clutch Slave Cyl

luftvagon wrote:I opted to completely rebuild my brakes...

Front Brake Pads
Rear Shoes
Shoe Hardware Kit
Brake Master Cyl
Clutch Master Cyl
Clutch Slave Cyl

Where are the new flexible brake hoses, young Luftwagonner?
Colin

Doh! How could I? Which place do you recommend? All 4?

luftvagon wrote:Doh! How could I? Which place do you recommend? All 4?

Try to find good German (ATE?) hoses with the understanding that "good German hoses" are merely the least sucky of the currently available hoses.
All four, you ask?
I ain't even answering that, Mr. I Have To Rebuild My Whole Brake System

Better to stop, than be stopped against some object :)