want to pick brains on 98 mustang gt brake bleeding problem

[black_demon69]

i know its not a ranger but

back story is a friend traded a truck for this POS and brake system is all screwed up. he just wants brakes to work so he can sell it. someone completely disconnected and cut the brake line leading from abs unit and the rear brakes. all fittings were loose, MC had power steering fluid in it proportioning valve was modified and leaking..

replaced MC and bench bled 2x, replaced proportioning valve, bled front brakes System had NO brake fluid in it so contamination was only in the MC. front brakes bled fine however the rear brakes wont bleed. i have used a vacuum bleeder (a modified glass peanut butter jar and my a/c vac pump), i have tried the old 2 man pump method. tried to gravity bleed, forced fluid from rear caliper to abs unit after disconnecting line from abs unit.. any other ideas?

 

[Dirtman]

Are you physically not getting any fluid to the rear or are you just not able to get the air out. If it's the latter you most likely have air in the ABS unit which needs to be activated in order to bleed out.

 

[black_demon69]

Are you physically not getting any fluid to the rear or are you just not able to get the air out. If it's the latter you most likely have air in the ABS unit which needs to be activated in order to bleed out.

not getting any fluid to the rear

 

[Dirtman]

I'm still voting on the ABS unit... one of the pistons could be stuck closed. If you can force fluid from the rear caliper to the line out of the abs unit but cant get fluid from the master to the rear when going through the abs unit I'd just make a short line to bypass it and see If it works. If so you know you've got a trashed abs unit.

 

[black_demon69]

i wonder if tapping with a hammer while someone pumping on brakes might make it work

 

[snoranger]

i wonder if tapping with a hammer while someone pumping on brakes might make it work

Don’t half-assed brakes just to sell it. Do it right or don’t do it at all.

 

[Dirtman]

Doubt it, the pistons need pressure from the ABS pump to return to the open position, the system relies on pressure from both sides. You could try jumping the pump to see if it kicks the pistons back but again. I doubt it.

 

[black_demon69]

Don’t half-assed brakes just to sell it. Do it right or don’t do it at all.

not my call but i agree with you....

 

[pjtoledo]

is the proportioning valve connected to the suspension?
I have no idea what's under a Mustang.

on some vehicles when the rear suspension drops during a fast stop the prop valve cuts off flow to the rear wheels.
those need bled with the weight on the wheels so the valve allows flow.

did the rubber line swell internally and close?

 

[RangerFabWorks]

if Memory serves me correctly. 98 had hydro boost brakes. Could be why you see power steering fluid in the master cylinder. The booster itself probably blew out.

 

[black_demon69]

turns out that that the proportioning valve was stuck and full of krud so I cleaned it and re assembled it using clean brake fluid to lube during reassembly.. then just completely bled the brakes.. now they are very touchy. lol

 

[black_demon69]

is the proportioning valve connected to the suspension?
I have no idea what's under a Mustang.

on some vehicles when the rear suspension drops during a fast stop the prop valve cuts off flow to the rear wheels.
those need bled with the weight on the wheels so the valve allows flow.

did the rubber line swell internally and close?

system was completely full of air so i just flushed alot of fluid through it power steering fluid was added to master but didnt go anywhere because system was empty and devoid of any fluid. proportioning valve is located just below master

 

[black_demon69]

if Memory serves me correctly. 98 had hydro boost brakes. Could be why you see power steering fluid in the master cylinder. The booster itself probably blew out.

yes it did have hydro boost. booster was not leaking and if it was to get into master it would discolor whatever fluid was in it (power steering system needs flushed bad) the powersteering fluid that was added to master was clear..

 

[black_demon69]

ABS is still jacked up because someone removed reloctor wheels and speed sensors... they just cut wires to speed sensors

 

[Dirtman]

And you let your friend trade a truck for this thing? Some friend you are!