darkestskydiver

OK here's the low down, i have an 89 runner 3vze the truck started off with a bad booster, it had a crack in the diaphragm and was causing the engine to surge when applying the brakes. that got replaced and that problem went away. since then the pedal was fading and there were no real brakes at all. bleed the system and that helped but still there was a slightly firm pedal but little to no stopping power. adjusted the back drums and that solved the problem for about a week.
then the problem returned but this time it was worse hit the pedal and it would go to the floor and there is nothing there. bleed the system again to no avail. fast forwarding to yesterday, i replaced the drums, wheel cylinders, shoes, and all hardware, rotors, pads, rebuilt calipers, and master cylinder, and adjusted the brake rod under the dash, bleed system twice. now the pedal is firm almost too firm and there is still no braking force .
going thru the forums the thing that i saw most was the lspv causing issues i took it off the vehicle and inspected it but the piston seems to always stay in the fully up position and it never droops when no pressure is applied would this cause the issues i am having? also where would one get this lspv? nobody seems to carry it. also on the passenger side frnt 2 lines split off and go to the front of the truck and go into this block thing which i thought might be some sort of abs but there are power steering lines coming out of it as well anyone know what this is? need to get this thing fixed.

Chickenman

You are gonna need to take some pictures...

A lspv (load sensing proportioning valve) determines how much pressure goes to the rear drums based on the height of the bed (basically). So what do you mean it doesn't move? Pictures!

What do you mean there's a block thing that 1 line comes in and 2 lines go out? Pictures!

A good way to tell if its abs or not is that there will be wires connecting into what ever the brakes lines head to. That way the computer can read what your brakes are doing...

But we need pictures!!

darkestskydiver

i'll take some pics tomorrow. the piston inside the lspv does not move on its own. i can get it to move if i pull it down with some pliers but when i disconnect the bar nothing happens with the piston. when i had it off the vehicle i blew some compressed air into the port from the mc and the air only came out of the port for the rear. nothing from the port to the front. so i assume it was delivering full pressure to the rear drums. but my brakes are far from it.

wyoming9

iTrader: (1)

from your post all your brake system but the lines has been replaced with new.

Just what are you comparing this lack of stopping with ??

If you have a firm pedal and no pressure and no friction on the rotors and drums. there is a blockage in the hydraulic system.

Are you having any fluid loss?? It is possible to have a connection suck in air but have very little fluid loss.

The Lspv just helps balance the brakes front to back depending on how much weight is in the truck.

You are using the E-Brake to keep the rear brakes adjusted up as you said when you adjusted the rear brakes all was good for a week

The block you see is where the 2 lines the one going and returning from the Lspv

If this has dirt or a crushed line and does not allow fluid to the rear brakes it could be a problem.

It can take a long time to bleed getting the air out of those lines.

Heck most of these valves have long since failed on most of the vehicles that pass through my shop.

Having no effect on stopping just balance front and back. The Lspv is a dealer only item or you can install a manual valve.

darkestskydiver

I'm not comparing it to anything but i think it should at least stop, i am manually adjusting the rear drums the e brake cable is snapped, has been since i got the truck. I'll look around some more i did not see any damaged lines on my first inspection. and so far there are no leaking fittings that i can see, and no fluid loss at all.

darkestskydiver

here is a pic of the distro block thing in the front of the truck.