91 4runner ,auto, v6, 4x4..... here is the problem .... changed the master cylinder ..... tryed to bleed the brakes cannot get any fluid threw the lspv valve body except straight threw the bleeder on it.... am getting fluid to the lspv and threw the bleeder but it wont go to the left or right lines..... checked the fronts they bleed fine.... took the lspv apart cleaned put back on still nothing..... what am i missing?.... can ya just get rid of this POS

 

also.... on the lspv body there is an arrow and an F ... i am just wondering if the lines got mixed up? what lines go to where on the darn thing?

 

Are you bleeding from the brakes as well? Sounds like you are just trying to bleed trough the valve.

 

yes they could get mixed up.

you said you took it off so did you make sure the lines going in were put back right?

you should bleed all 4 corners then the lspv last.

 

yes i tried to get fluid from the bleeders rr first..nothing...lr nothing.... fronts worked fine????.....so back to the rears... nothing at the bleeders... follow the lines disconnect the line going to the rears from the lspv nothing.. reconnect .... disconnect the return line on the lspv ? the one with the arrow?....nothing.... then the line coming from the master cylinder.... fluid when the pedal is pressed... it is, was in the lspv hole with the F........then checked the bleeder on the lspv and it is giving fluid....then thought must be clogged took off reinstall same as before......same prob i know you are to start at the farthest from the mc ....but i cant get any thing from the bleeder using the old fashioned pumping the pedal..... or the hand pump at the bleeder...with the bleeder open! it just colapses the clear plastic hose?.......this should be easy to do....what am i not doing?

 

all i can think of is you have the lines backwards


The top line should trace back to a T behind your passanger front wheel. The lower line on the LSPV is from the MC and it traces back to an elbow next to the other T behind the pass front wheel.

Then obviously the line coming out the side of the LSPV goes to your rear brakes.



If all else fails you CAN replace the LSPV with a manual proportioning valve but I'm not certain how this 'effects' stock drum brakes. We do this on disc brake conversions... I however just added in a manual valve to supplement the stock lspv.

Where is the sensing bar located? You dont have it dangling straight down as far as it'll go do you?

 

is the truck sitting on the ground or jacked up and resting on the frame ?
what I am asking is the axle hanging down farther than normal?

also the last brake job I did bled out the system 3 times and the rear still was very slow I remover the rear cylinders and they where full of gunk I ended replacing them with some new ones and the problem was solved for me

 

Could the bleeder screws on the rear wheel cylinders be clogged? Take them off and spray brake clean through them to check.

 

Well..you've got the order right. Most people mess up here. When you are trying to bleed these...are you doing it with the engine running or are you just pressing on the brake peadal?

 

when i bought my 79 the previous owner bypassed the lspv, so when i took my bed off i also too it off as well, i read up on it over on Pirate and found that if u have bigger tires (33+) the lspv becomes obsolete, if not worsening rear brake preformance, if ur still running stock tire size, i would keep it

have you tried a mityvac?

 

so should you bleed them with the motor running or not?

 

not running... pump three times, and hold.... it should be hard as hell.... I stick a 2x4 into my seat to hold the pedal///// now go round and let the pressure out the brakes you want to bleed.... repeat at each point till it streams out with no bubbles or sputtering... you want a flat stream........ make sure you dont run outta brake fluid in the resevoir!!!!!!!!!!!!!!

 

im actually having a different problem that may be related to the lspv, my front brakes are locking up on there own, they start out fine and after about a mile or to the pedal gets really hard and then the front brakes start to drag and then they lock up...any help would be great

 

Locking brakes is due to the brake pedal extension pin putting pressure on the mastercylinder plunger. There are instructions in the mastercylinder box explaining this critical adjustment that MUST be verified/changed when you replace a mastercylinder. I have been there and experienced that....