Hey all, I know there are other similar threads but there are a couple things I'm experiencing that no one has mentioned in any of the other posts I've read.
First off I've got an 84 4x4 standard cab pickup with a five speed and a 3 inch suspension lift it's had since new. I just got it and I'm straightening the body, repainting it and fixing all the mechanical issues. So far I've replaced the rear brakes with new wheel cylinders and hardware, and replaced the axle seal and bearing that was leaking. The master cylinder looks like it has been replaced recently but I'm not 100% on it.
My problem is the brake pedal doesn't grab or get hard until it is almost to the floor. No amount of brake bleeding seems to help. I noticed when bleeding the brakes yesterday with the assistance of a buddy that I only get a small drip of fluid from the rear wheel cylinders when the bleeder is wide open. I get a full stream from the lspv bleeder and tying the lspv rod up all the way (which should be fully open?) Doesn't make any difference. Also the master cylinder has two lines that come off it, one on the end that faces up and one in the middle that comes off the side. When bleeding the master on the truck I get no fluid from the side line.
I'm thinking that I either have a problem with the lspv, bad soft lines, a bad master cylinder, or the booter rod is way out of adjustment. I'm not familiar enough with this brake system to know how things are supposed to react.
Please help!!

 

The first thing you need to be sure of it: when you replaced the rear brakes did you adjust the shoes? if not that is why, it takes up a lot of pedal travel before they touch the drum and you feel the pressure build.

 

I definitely got the shoes adjusted up tight. Does it sound like the lspv if functioning correctly?

 

Not being there makes this a tough one, it sounds like you are trying all the right things (tying up the LSPV and such). Since the master cylinder looks new there may be issues with the pushrod length, but maybe it wasn't bench bled. It takes a ton of bleeding through the brake lines if you don't bench bleed it. When you say you get no fluid from one of the ports it sounds like you have a bad master cylinder.

 

Thanks for the help AKwheeler! Just verifying I should be getting fluid from both ports right? The one closest to the firewall isn't a return line or something stupid like that? Otherwise I think replacing the master with a known good unit is my next step. I should probably do the soft lines as well. Does anyone sell extended soft lines for a lift or am I going to have to get them made? The old ones seem too short to me.

 

Yes, you should get fluid from both ports, one is for the front brakes and one for the rear, no return lines. Fluid from the reservoir fills the lines and maintains level. When you push on the brake pedal the piston inside the master cylinder closes off the port between the lines and the reservoir and then pressures up the lines moving the pistons in the calipers and slave cylinders.
Longer brake lines should be available from anywhere you could buy a lift like Trail Gear.
A known good master cylinder might be a good move at this point, you could try running a short piece of hose from that port back to the reservoir (doesn't need to hold pressure just submerge it in the fluid) and slowly pumping the brakes (this is bench bleeding).

 

Thanks for the advice. I'll post how it turns out.

 

I have had problems with aftermarket brake master cylinders where the front port does not let much fluid out.

I had three bad ones in a row where I could not get more fluid out, even after bench bleeding it. https://www.yotatech.com/forums/f116...oblems-290711/

Like akwheeler says, try "bench bleeding" and see what you get.

If you are sure that the master cylinder is bled, then I would look at replacing it.

 

New master cylinder fixed the problem! I also threw in new steel braided lines for good measure.