No pressure to rear brakes (HELP!)

[OneJArpus]

Ok, i have all rebuilt calipers and earls brake lines... i was painting my calipers and decided to disconnect my fronts completely as i anticipated a full flush to synthetic DOT 4 fluid. After all the painting and hard work.. the master was dry, i fill n bench bled the master cylinder, i then install, hook up the brake lines, i have perfect pressure for the front but NO pressure what so ever for the rear..... WTF???? I had a vac bleeder type that i used on the LR wheel for about 1 HR straight pulling 30 lbs n dropped to 15lb's and repeated for 1 hr and NO fluid made it to the back =/.... Any ideas?

I the tested both fronts to see if the MC was working and it was indeed working... i took a MC off a friends car who was working to test the theory of a bad master but it is doing the same exact thing

88 TURBO ABS Brakes 5SP
NO BENT LINES
NO LEAKS
BENCH BLED MASTER
FILLED MASTER
FRONTS BLEeD N HAVE PRESSURE
PEDAL SOFT
NO REAR PRESSURE OR FLUID COMING OUT OF CALIPERS

 

[mkiiichip]

Try the old fashion, two person bleeding method?

 

[barkz]

ABS? and just curious why you bled the fronts before the rears?

 

[OneJArpus]

Try the old fashion, two person bleeding method?

I've done that, when someone pumps the brakes and holds, i open the bleeder valve in the rear the pedal doesn't depress and no air comes out. I did that for an hr on 1 wheel!!

i also used a vacuum style on that same wheel for an hr. I've looked over the entire brake system for leaks or loose connectios... I can not find anything, nor do i hear anything... I've also put air thru the rear lines to see if there was a block and the lines were clear...

ABS? and just curious why you bled the fronts before the rears?

After trying the regular way i wanted to see if there may be a block some where or if the fronts were working. I did set it up again so I can start it over the correct way after getting frustrated.



Also, today i took a fitting and hooked it up to the "T" at the rear of the car which feeds the rear calipers. I hook up a vaccum bleeder directly to the fitting to see if it will hold pressure inside. It drops fast.


So stumped.... I took the car down the block and slammed on the brakes in an attempted to rush fluid into the ABS unit while it is bouncing the solenoids back and forth, but! After a few minutes the master cylinder didn't go down at all =/

 

[barkz]

soooooo, maybe your abs solenoids(just rear) are junk? idk this does sound different....

 

[OneJArpus]

soooooo, maybe your abs solenoids(just rear) are junk? idk this does sound different....

I was reading more on the ABS unit and in the event of a solenoid going bad they should be stuck in the OPEN position so they still provide brakes.... I'm taking off the proportional valve & ABS unit from a donor to see which is messed up....

 

[barkz]

well that makes sense. hopefully just the prop valve. little easier/cheaper than the whole abs unit lol

 

[OneJArpus]

well that makes sense. hopefully just the prop valve. little easier/cheaper than the whole abs unit lol

Yea both are cheap $0.00 i have tons of parts laying around lol

 

[barkz]

lol well in that case... off topic but, you say you have parts...any burgundy interior parts?

 

[spikesnstuff0905]

Barkz, PM sent.

 

[OneJArpus]

Nope gray interior parts

 

[mkiiichip]

Well to start narrowing down the possible failures.

Have someone push on the brake pedal.
Crack the rear brake line loose, at the master cyl. Keep loosening, until the pedal goes to the floor. Re-tighten.
Keep moving down the line, to the rear calipers to find the issue.


I bet its the MC. When you move the piston further than it is used to moving, corrosion in the sleeve, tends to ruin piston seals.

 

[barkz]

is there brake fluid leaking where the MC meets the booster? great sign that your seals are junk

 

[OneJArpus]

Well to start narrowing down the possible failures.

Have someone push on the brake pedal.
Crack the rear brake line loose, at the master cyl. Keep loosening, until the pedal goes to the floor. Re-tighten.
Keep moving down the line, to the rear calipers to find the issue.


I bet its the MC. When you move the piston further than it is used to moving, corrosion in the sleeve, tends to ruin piston seals.

I bench bled it with it in the car n the special fittings. Master cylinder is good. No leaks on MC.... but i will try this out! thanks

is there brake fluid leaking where the MC meets the booster? great sign that your seals are junk

No leaks.

 

[OneJArpus]

My new master must be bad too or something.... just replaced the proportional vavle then the ABS module and still no rear brake pressure. After 2 hrs of using a powerful vacuum bleeder my boss had the rear is still no good... going to buy a new master tomorrow and see what happens

 

[OneJArpus]

WOW this is ridiculous!

Returned the MC i got yesterday and ordered another 1 from a different vendor. Same fucking issue! No rear brake pressure. You get 1 good pump out of the MC of good pressure then it just fills up with air after that. I might just need to dish out the cash for a brand new one for toyota =/

 

[OneJArpus]

Problem solved, used a phoenix injection system.. Injected fluid from the caliper to the master cylinder now its all G... Tons of air inside the system was preventing proper bleeding.