nOOb pressure bleeding

[johnnychimpo]

I built a pressure bleeder to do my brakes. I put a new master cyl (bench bled on the truck) lines, hoses, & calipers for the front. I'm running 13" rear drums. When I pump up the garden sprayer(it's got plenty of fluid in it) & crack the rear bleeders I get nothing coming out. But if I pump the pedal w/ the bleeders open I get fluid. Anyone know what I'm doing wrong, I haven't a clue

 

[johnnychimpo]

ttt

 

[merace19]

How are you applying the pressure with the sprayer? where?

 

[sandawgk5]

Are you pressurizing the side you are cracking?

Dik

 

[dremu]

1. Press the rubber button on the combo valve.

2. As mentioned, are you pressurizing both sides of the master, or just one? On some masters the divider goes all the way to the top so you may need to have two holes in your top plate.

Posting pix of your master and your bleeder would likely help.

-- A

 

[merace19]

What he said..............

 

[johnnychimpo]

to the MC. I used a 1/4"plate with a 1/4" pipe threaded barbed fittting. I clamped it to the MC on the front reservoir (small one. I traced it to the rear brake line)

 

[johnnychimpo]

Yeah, I traced the line to where I'm bleeding from.

 

[johnnychimpo]

1. Press the rubber button on the combo valve.

2. As mentioned, are you pressurizing both sides of the master, or just one? On some masters the divider goes all the way to the top so you may need to have two holes in your top plate.

Posting pix of your master and your bleeder would likely help.

-- A

I tried to press the button on the combo valve but it wouldn't budge. How hard should it be to push it in?

Just pressurizing the front reservoir ( rear drums) My divider goes all the way up & I drilled the plate to be able turn & reach each reservoir.

pics of my bleeder

 

[dremu]

I see I'm not the only one who can't make one clamp fit right (whew!)

Anyway, a brief background:

The valve in question is a combo valve, not only proportioning front pressure to back, and keeping some residual pressure for the one side (is it front or rear? I forget) ... but also acts as an emergency cut-out to block either front or back in case of severe pressure loss. This is a back-and-forth sliding mechanism that, if the front or rear circuits has waaay more pressure than the other, blocks the lower-pressure side. (I think that's right -- it's from memory from tearing down a coupla combo valves last year.)

Anyway, the rubber nipple covers a metal button that slides back and forth, and will reset this latter blocking mechanism. It should just press in with finger pressure. You may want to remove the rubber cover -- don't tear it, it should pop out with a little finagling with a small flathead -- and then just press the metal pin.

You should reset the thing before applying any pressure to the system. I seem to recall the factory manual saying to use factory tool #J-12345678 to KEEP it reset, and I've built one (per the Chilton's that shows you how) from a piece of flat stock.... but I also seem to recall not bothering and getting good bleeds without it.

Then again my plate has two fittings on it so I can pressurize both sides at once, which would presumably not make the combo valve freak out. The home-made tool is basically a piece of, say, 1" x 1/8" flat stock, maybe 4-5" long, bent on one end to fold over the button, and with a slot in the other end ... you loosen the bolt that holds the combo valve onto the crossmember, then slide this tool in there and figner-tighten it, and it holds the button in.

If that doesn't make sense, lemme know and I might have a picture of mine somewhere, or I'll find the relevant section in the Chilton's and post it up here.

Dang, sorry that was so long... but hopefully it'll help. I went through, I kid you not, like six gallons of brake fluid learning to pressure bleed when I had issues with my crewcab ... and that thing will stop on a dime now, and unless I'm towing it'll give me change back

-- A

 

[johnnychimpo]

I took the rubber cap off the combo valve. The button on my '79 looks like one brass piece prolly 5/16" in dia. I have a combo valve from an '82 K30 & the button looks like a valve stem core.
I had some rust come through in the lines I though it may have clogged the bleeder screws but I could pump the pedal & get fluid. I could not with the garden sprayer. Does it look like I missed anything with my setup? I have another barbed fitting so I could add it later .
I don't have my pressure gauge in yet. How do I tell how much should I pump it without the gauge?

 

[dremu]

Well, I've found 15-17psi is about as much as my system can take ... that's pumping it like crazy until your hand hurts.

Yet another truck thing that sounds lewd: Pump it up until ii's stiff and your hand hurts

I remember seeing considerable variety in the combo valves, but I don't remember seeing one as big as 5/16".

-- A