Need help troble shooting the air over hydrolic breaks

[WoodDeuce]

Recently when I was driving my deuce I noticed the pedal was starting to feel a little soft. I got under the truck and found the hard line from the master cylinder to the booster was cracked. So I replaced it, blead the booster and master cylinder and went around bleading the breaks as you would any other vehicle. It was goig good untill my pedal went to the floor and now does nothing... It wont return from the master cylinder. Anyone have any ideas????

 

[Jones]

Depending on age and use of your deuce, you may also have a broken return spring in the master or it's check valve may have some junk in it.
Same with the booster which kinda acts like a secondary master cylinder.

Generally brakes are bled from the furthest wheel back to the master cylinder. If you started in between you may have gotten a little air in the lines and that's all it takes.
That's a fairly large system compared to a car or pick-up so it'll take a fair amount of fluid.

Best done with a helper; pump the pedal and hold it down, break the bleeder loose then re-tighten. Repeat for every bleeder 'til you're only getting pure fluid.
Make sure the master stays full while you're doing this. If it consumes enough fluid to dry out and take a gulp of air, you get to do it all over again.

 

[WoodDeuce]

Thank for the advice. I was told by a buddy of mine that has some larger trucks that you want to blead the booster first then the tires and back to the booster... I dono why but I tired the normal car way and nothing seemed to get better then I tried his way and it was good for awhile. now it just seems like the master cylinder it self is not returning to where it should be inside even if I move the pedal up and down.

 

[hole]

I was just recently schooled on this. Start with the airpack first, then right rear dual. Then left rear dual, right front dual, left front dual, right front , left front. This was made stupid easy with the use of Will Wagner's power bleeder ! I had a wheel cylinder let go, and decided to flush the entire system and switch to dot3. It took over a gallon to flush out the old fluid.

 

[glcaines]

You are much better off with DOT 5, which is silicone based, not glycol based. DOT 5 is very expensive in stores, but you can find it very inexpensively sold by the gallon by many MV parts suppliers and on E-bay. DOT 5 does not attract water like DOT 3 does.

 

[renovate7]

There used to be someone who sold BFS (Brake Fluid Silicone, Dot5) for about $15 a gallon. Always had an add in the Classified Section.

 

[hole]

Out here in hot and sunny So-Cal, moisture isnt my concern. I dont ford streams or water crossings. Finding mil spec dot 5 in the middle of nowhere is my concern. Almost any gas station or convienence store will carry dot 3.

 

[Heavysteven]

bleeder screws use 3/8" tubing available at home depot. I just did mine twice. Bleed the booster first and I used a pressure bleeder.

 

[offroadrunner]

Another DOT-3 vs BFS rant follows...

Out here in hot and sunny So-Cal, moisture isnt my concern. I dont ford streams or water crossings. Finding mil spec dot 5 in the middle of nowhere is my concern. Almost any gas station or convienence store will carry dot 3.

Hole,

You probably don't want to hear this now, but DOT-3 finds moisture to take out of the air even here in sunny So-Cal (that's why all the bottles of DOT-3 have "Keep tightly sealed" warnings). The truck I got last year had been converted to DOT-3 by the previous owner sometime between his purchase (from Pendleton) in 1999 and when I picked it up last year (his place is out in Santa Clarita, which is pretty dry). I knew when I got it home that I'd have to do all the wheel-cyls, since at least 3 were leaking enough to show up on the backs of the wheels, but when I got them apart, they were filled with rust! (Very little rust elsewhere on the truck though - so I doubt it was because of water-crossings, etc.) This had of course chewed through all the rubber seals - causing the multiple leaks.
Here's my reasoning: the military master-cylinder doesn't have one of those accordian-like gaskets like the civy cars do to completely seal out moisture; they're just vented to the outside. At best they go through an air-line to the air-filter housing (if that line is still there on your truck - mine wasn't), but that's still open to any humidity available in the air around us; and DOT-3 acts like a sponge for that moisture and (over time) slowly distributes it through the entire brake system. This is why I converted back to BFS on mine; I'll just carry several bottles with me in the truck - so I don't have to worry about finding a store that carries it.
Of course converting back from DOT3 to DOT-5 costs more than just the BFS. Since DOT-3 causes some swelling of the rubber parts, and that seems to go away with DOT-5, most rubber parts seem to leak (almost like they "took a set" to the swelled-state of DOT-3) when you go from DOT-3 to DOT-5. I've converted a couple of vehicles from DOT-3 to BFS, and if I forgot to replace any old rubber parts with new in the process, they usually start leaking within the next few months. So I wind up replacing everything eventually. I'm generally as cheap (frugal?) as the next guy, but it's still worth it (for the advantages of DOT-5) to me in MVs. Just my 2-cents.

End of rant.