Help bleeding brakes?

[rddiaz]

Hey guys,
I've been trying to get my brakes to work so I can actually roll it outside and pressure wash the frame before I paint it, but I can't seem to get them to bleed right. I mean the back wheels bled fine but I can't get the front to. I thought it was the combo/prop valve but there is no brake light in the cab, so I tested it anyways with a tester light like the (CPP link )mentioned, it said if the light didn't come on, it was positioned in the middle; otherwise good! So what am I not doing? or maybe I'm doing something wrong? please let me know.......thanks ahead of time.

[6772owner]

So you have a new combo/prop valve then? the brakes worked fine before you changed it? Is there a problem with the master cylinder? do the front brakes work at all or just still have air in them? What method are you using to bleed them? Sorry for all the wuestions, just trying to narrow it down a little.

[rddiaz]

hey (67720wner)
sorry I didn't leave much info last night but it was late; so here it is, I have an 86 SWB everything worked fine until I took everything apart to clean and paint the calipers, all the fluids were drained out of them and the lines were left to drip out, but it never ran dry in the MC. NO problem with the MC that I know of!!! nothing seems to come out of the front, and I am bleeding them the usual way, with a plastic tubing and clear plastic bottle with brake fluid in it pump 1,2,3, then keep pressed and repeat. Not sure if it is the combo or prop valve but they both sound the same to me, I might be wrong!!!!!
I added some pictures because I know everybody likes them!!!!


Kinda hard to get to, it is in between the frame horns!!!!

[SCOTI]

I went through this problem on my 74. I swapped the prop valve thinking it was part of the issue.

My standard method is to get an assistant to slowly pump the pedal twice to build pressure. Then I open the bleeder valve to purge the pressure/air. Once the pedal drops all it will drop, my assistant keeps it down while I close the bleeder. When the bleeder is closed, they can release the pedal.

What I found was the initial pressure was working against the prop valve. I tried putting no pressure @ all on the pedal. Open the bleeder & have an assistant slowly press the pedal once & hold it down. Once bottomed, I close the bleeder & they can lift off the brake.

I did it this way & they bled w/o any further issue.

[6772owner]

In my experience if the master runs dry you have to bench bleed it. You might be able to leave it on the vehicle to bleed it but its going to be difficult to get all the air out I believe. Hopefully someone with more experience will chime in, but I think its best to bench bleed it if it ran dry. Also just as a note, I would clamp off the line(s) if you have to disconnect them to prevent this from happening. :-) Good luck

[rddiaz]

Thanks guys, I will try your suggestions scoti I hope this will be it, cause I'm not wanting to bench bleed the MC. What a pain in the arse!!!!!!!

[fixit-p]

You should be able to bleed the master cyl while still on the truck just remove the brake lines from the master cylinder screw in some plastic adapter tube fitting and loop your clear plastic lines into the mc below the brake fluid level and pump slowly until there is no more air bubbles, but Iwould try scoti's idea first.

[rddiaz]

Well guys I finally got the front brakes to bleed, it was the simplest of things.
As I tried doing what scoti had suggested, I still had nothing coming out so I figured some thing must be clogged, and it must not be letting any fluid out, so I decided to pull out the bleeder screws and pump it a couple of times to see if it was getting any fluid to the caliper, and damn what a mess!!.... so that was getting fluid, then I checked the bleeder screw and what do you know, couldn,t even find the hole on the bottom of it, it was so clogged up with rust and crap. I was so excited I cleaned it out put it back in on both sides and then I forgot to take a pic, tried bleeding again and it worked.......... Thanks again... I'll have to buy new ones tomorrow!!!

[SCOTI]

If your master cylinder didn't empty itself, try the 'low pressure' bleed before replacing parts.

My guess is my original prop valve prob still worked. I swapped in the new one I already had for another project since it was handy. I sure was pissed when it did the same freaking thing w/the new valve. As you've noticed, they're a PITA to service because of the location so I just left it as is.

[6772owner]

Sweet glad you fixed the problem, I have never even seen bleed screws that were clogged shut! WOW Glad you are stopping again.

[el curioso]

At auto zone they sell some bleeder screws that have a check valve in them they work very well.

[fixit-p]

Originally Posted by el curioso

At auto zone they sell some bleeder screws that have a check valve in them they work very well.

I've seen those online they're called speed bleeders I've never used them and they look like hey would work really well and allow for a one man brake bleed but when I upgrade to them I'm going to flush my lines because if I have some crud in the lines as with this thread I can see it could prevent the check from seating properly and suck air.