Brake Problems PLEASE HELP!!!!

[lil_red_wagon]

Im workin on a 93 xj 4.0 AW4 NP233 HP30 C8.25 non ABS.

It came in with a empty rear section of the master cylinder and no brakes.

Long story short i have installed 4 master cylinders(3 new, 1 reman), on the rear wheel cylinders on both sides, shoes, and drums, on the front new calipers ad rotors, also have replaced all metal lines and rubber hoses, also installed new proporsitioning valve, and tried a new booster no diff.

What happens is you can pump to build brakes. let it sit for a few seconds pedal goes to the floor. We have bleed the brakes usein all the methods known. Even used a mityvac on it. I have no air anywhere. Pull 16oz of fluid through eace front wheel and 9oz of fluid through the rears. Brakes hold well when you pump them up. Rear brakes are setup really well.

 

[Texas Twitch]

Did you bleed the actual master cylinder? There could also be a problem with the poor excuse of a booster sitting behind the master cylinder, have you done any work on that at all?

 

[Texas Twitch]

nevermind, just saw you tried a new booster.

i guess my only advice would be to bleed the actual master cylinder itself. If you were closer, I'd offer to come over and help, but hot springs is a wee bit far...sorry dude!

 

[magimerlin]

hows the vacuum source from the intake? what about the check valve? When it is running does it still goes to the floor after pumping it then stopping then reapplying? Or is it only when Jeep if off?

Something isn't right if you replaced everything already. But you know that already...

Did you make new lines and double flare them or join a few pre made ones together with the female threaded unions(I do not mean the compression unions either)?

I would double check all the fittings even though you have probably done that about 10 times now, or better yet have some new eyes look for/at then to.

Do not forget when you bleed the master to try to have it as level as you can

 

[magimerlin]

after thought... This isn't a booster upgrade setup is it. If so it need the spacer between the firewall and the booster for correct pedal rod usage.. Just a thought. If not an upgrade disregard this idea...lol

 

[Texas Twitch]

I'd also check all the -AN fittings going into the master cylinder, proportioning valve, etc. and make sure they aren't stripped and aren't leaking fluid and letting air get into the system. Check to make sure the wheel cylinders and calipers aren't leaking any fluid out too, at the fittings.

 

[Texas Twitch]

Dangit MM, i was in the middle of posting when i had to walk my dog and you beat me to the fittings idea!

 

[lil_red_wagon]

no it wasnt the fittings. i had the calipers reversed. so the bleeder was on bottom ont top. the boxes had the same part number so i just grabbed one and stuck it on then the other didnt think about the bleeders bein in the wrong spot. its now fixed someone posted up in the oem tech sec got it fixed.

 

[Texas Twitch]

good to hear man!