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Brakes won't Bleed a stumper? by Dennis LaGrua
Started on: 06-24-2019 06:20 PM
Replies: 9 (413 views)
Last post by: Dennis LaGrua on 07-05-2019 06:33 PM
Dennis LaGrua
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Report this Post06-24-2019 06:20 PM Click Here to See the Profile for Dennis LaGruaSend a Private Message to Dennis LaGruaEdit/Delete MessageReply w/QuoteDirect Link to This Post
Front wheels on an 85 that I am restoring were locked to the rotors so I determined that it was time to do a brake job. Replaced both front calipers, rotors and brakes lines. After all parts were replaced, I opened the bleeder screws, attached the Mityvac bleeder , pulled a high vacuum and nothing flowed on either side, Master cylinder reservoir was refilled but fluid is not flowing to the calipers. I have done numerous brake jobs but have never seen anything like this. Wondering if a bad master cylinder could be the culprit,

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
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87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

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Report this Post06-24-2019 08:08 PM Click Here to See the Profile for SpoonSend a Private Message to SpoonEdit/Delete MessageReply w/QuoteDirect Link to This Post
Hi Dennis, maybe those bleeders missed the drilling process. Pull one out of the caliper and have a willing subject push the pedal. You may want to do the same for one of the rears. If no flow at either end I'd suspect a blocked master cylinder.

By the way what did you find with that flywheel noise?

Spoon

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Tony Kania
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Report this Post06-24-2019 09:46 PM Click Here to See the Profile for Tony KaniaSend a Private Message to Tony KaniaEdit/Delete MessageReply w/QuoteDirect Link to This Post
Crushed lines?
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Dennis LaGrua
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Report this Post06-24-2019 10:01 PM Click Here to See the Profile for Dennis LaGruaSend a Private Message to Dennis LaGruaEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Tony Kania:

Crushed lines?

Could be but on both sides? Will check.
 
quote
Originally posted by Spoon:

Hi Dennis, maybe those bleeders missed the drilling process. Pull one out of the caliper and have a willing subject push the pedal. You may want to do the same for one of the rears. If no flow at either end I'd suspect a blocked master cylinder.

By the way what did you find with that flywheel noise?

Spoon


Will check that tomorrow but two different makes of rebuilt calipers having the same problem would be strange. Leaning towards a stuck proportioning valve or a blockage someplace. Will just check point by point for fluid to see where the blockage is.
As for the clicking noise, it is coming from between the engine and transmission. Found it with my homemade stethoscope; a length of 3/4" rubber hose with a funnel taped on one end for an earpiece. Best guess is a loose or broken flexplate or some interference with the flexplate. Not ready to drop the trans just yet but its a very strange problem as it comes, goes and changes intensity. .


------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

[This message has been edited by Dennis LaGrua (edited 06-24-2019).]

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Report this Post06-25-2019 11:47 AM Click Here to See the Profile for 2.5Send a Private Message to 2.5Edit/Delete MessageReply w/QuoteDirect Link to This Post


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Report this Post06-25-2019 12:48 PM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreEdit/Delete MessageReply w/QuoteDirect Link to This Post
Likely Combi valve next to MC is plugged.
Combi have small holes can get plugged and won't bleed etc.
Old wet fluid can't protect the system for "rust" and aluminum and steel part in it can "rust weld" themselves close and plug the valve.

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Dennis LaGrua
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Report this Post06-25-2019 03:19 PM Click Here to See the Profile for Dennis LaGruaSend a Private Message to Dennis LaGruaEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by theogre:

Likely Combi valve next to MC is plugged.
Combi have small holes can get plugged and won't bleed etc.
Old wet fluid can't protect the system for "rust" and aluminum and steel part in it can "rust weld" themselves close and plug the valve.


That valve is on the list to check tomorrow but I thought that it was a proportioning valve.

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

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Report this Post06-25-2019 07:38 PM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Dennis LaGrua:
That valve is on the list to check tomorrow but I thought that it was a proportioning valve.
Prop valve is only 1 function of combi valve and only affects the rear brakes.
Balance bar section plugging will affect one or both fronts, rears or all.
See my Cave, Combination Valve
(Note: Normal path is correct. LM just didn't mill to show hole from D to prop valve.)

Balance bar or MC pistons moving doesn't mean body of them is clear. Many over torque the fittings and crush the hole close before stripping.
If you look at combi page can see some damage in MC Pri port vs MC Sec port and outlets. MC can get same damage or worse. Any steel flare can wreck aluminum shells.

So If you replace MC or think others have, check for fitting hole damage in the MC first.
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Report this Post06-25-2019 09:49 PM Click Here to See the Profile for La fieraSend a Private Message to La fieraEdit/Delete MessageReply w/QuoteDirect Link to This Post
Dennis,bleed the Master Cylinder first, open the caliper's bleeders and apply vacuum. If you don't see fluid
get inside the car and pump the brakes while applying vaccuum. Sometimes you need pressure to push the fluid
when vaccuum doesn't have enough force.
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Dennis LaGrua
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From: Hillsborough, NJ U.S.A.
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Report this Post07-05-2019 06:33 PM Click Here to See the Profile for Dennis LaGruaSend a Private Message to Dennis LaGruaEdit/Delete MessageReply w/QuoteDirect Link to This Post
UPDATE: We tried to bleed everything when pumping the pedal but the front calipers would not fill with brake fluid. Replaced the proportioning valve and fluid is now moving through the lines. At this point it appears to be a clogged proportioning valve.For anyone replacing that valve allow a couple of hours of labor. Its not easy getting five 34 yr old flare fittings removed from the proportioning valve without breaking them but we did. Had to remove the spare to get to the two flare fitting at the bottom. Just didn't enjoy this job.

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

[This message has been edited by Dennis LaGrua (edited 07-05-2019).]

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