New Brake Booster Install FAIL
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New Brake Booster Install FAIL
I just installed a new brake booster 51-8026 and at first it pumped fine and I bled any air from brake fluid that went to the booster. When I attempted to bleed my brakes suddenly the brake pedal would not depress. I started all over by disconnecting fluid lines and testing vacuum from engine but still the pedal will not depress.
Just for grins I tested brakes by moving vehicle and NO BRAKES, just a hard to press pedal.
I can't find any instructions and calling cardone who rebuilds these was of no technical help.
Any Ideas ???
Just for grins I tested brakes by moving vehicle and NO BRAKES, just a hard to press pedal.
I can't find any instructions and calling cardone who rebuilds these was of no technical help.
Any Ideas ???
Logistics Pro
Joined: Sep 2014
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From: Bothell & Silverdale, WA
There also may be a hydraulic lock between the master cylinder and the booster. Check those lines & fittings for debris. Also, the booster cylinder may be locked up (defective booster). Disconnect/loosen the line between the master cylinder and booster and try your pedal again. Possible mess may ensue.
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Bob, I disconnected the master cyclinder to the top fitting on booster since that seems to be the one that "feeds" it. There in lies the issue. The pedal pumps fine with plenty of juice going to this loose fitting but once I connect it firmly again the booster does not move and no juice comes out of the second line back to the master... Is there a way to force this to bleed or what is next?
Thanks for responding...
Thanks for responding...
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Yes, I had the lines off but since one was so much longer and the routes were very clear so I simply put them back the way they were...
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Logistics Pro
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From: Bothell & Silverdale, WA
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Logistics Pro
Joined: Sep 2014
Posts: 4,920
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From: Bothell & Silverdale, WA
Bob, I disconnected the master cyclinder to the top fitting on booster since that seems to be the one that "feeds" it. There in lies the issue. The pedal pumps fine with plenty of juice going to this loose fitting but once I connect it firmly again the booster does not move and no juice comes out of the second line back to the master... Is there a way to force this to bleed or what is next?
Thanks for responding...
Thanks for responding...
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Bob, Firstly I have the Hy-Power not the hydrovac which is the diagram you provided.
This model has two lines to the master cyclinder... At first I could push the fluid through it for bleeding the chamber in the booster but now it won't budge despite confirming there are no blockagesin lines or fittings. I have removed both vacuum lines, the one from the engine and the one to the vent inside cab. Yet now I cannot get the pedal to depress much... it seems something like a check valve inside is preventing it but cannot find how to release it and start over...
This model has two lines to the master cyclinder... At first I could push the fluid through it for bleeding the chamber in the booster but now it won't budge despite confirming there are no blockagesin lines or fittings. I have removed both vacuum lines, the one from the engine and the one to the vent inside cab. Yet now I cannot get the pedal to depress much... it seems something like a check valve inside is preventing it but cannot find how to release it and start over...
Logistics Pro
Joined: Sep 2014
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From: Bothell & Silverdale, WA
Ok, sorry 'bout that. Your Midland must be the counterpart to my Bendix.
I thought the slave/power piston might be the culprit, also the ball-check valve.
Dave sez:
BRAKE PEDAL IS HARD AT DIFFERENT INTERVALS
http://dave78chieftain.com/MidlandRoss.html
I thought the slave/power piston might be the culprit, also the ball-check valve.
Dave sez:
BRAKE PEDAL IS HARD AT DIFFERENT INTERVALS
- Defective manifold check valve.
- Slave cylinder piston sticking from inferior brake fluid.
- Brake booster air cleaner clogged.
- Clean or replace manifold check valve.
- Clean and recondition slave cylinder.
- Clean air cleaner in mineral spirits and blow dry with compress air.
http://dave78chieftain.com/MidlandRoss.html
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Bob, Wow thanks, I've been looking for this documentation for almost week now. Yes, this is the model and exactly the kind of original manufacturer troubleshooting steps I need to try before I get another one only to find out it was not defective and I have no idea what I am doing... hehehe
thanks again
thanks again
Senior User
Joined: Nov 2014
Posts: 155
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From: Beaverdell BC
Hulaman,
I've got the hy-power one too. Had John Stuart Power Brake up here in Canada to rebuild mine.
Replaced the master cylinder too, so bench bled the master before installing it. Can get nasty air locks otherwise sometimes. IIRC, the middle port on the distribution block from the master is your outlet to the booster. Any of the others can be used as the inlet as the all share the same passageways for distribution.
Sounds like something is funky inside the booster, had no problems bleeding mine.
Btw, the service manual does cover both types of booster quite well for all the procedures.
I've got the hy-power one too. Had John Stuart Power Brake up here in Canada to rebuild mine.
Replaced the master cylinder too, so bench bled the master before installing it. Can get nasty air locks otherwise sometimes. IIRC, the middle port on the distribution block from the master is your outlet to the booster. Any of the others can be used as the inlet as the all share the same passageways for distribution.
Sounds like something is funky inside the booster, had no problems bleeding mine.
Btw, the service manual does cover both types of booster quite well for all the procedures.
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Thanks Guys,
Well after much sweat and tears it turns out this booster is bad and am returning to o'reilly since it has lifetime warranty. Too bad I got one that looked like it had been returned once already since there were all kinds of rusting funky spots in those usual suspect areas...
This forum is a life saver... thanks again
Well after much sweat and tears it turns out this booster is bad and am returning to o'reilly since it has lifetime warranty. Too bad I got one that looked like it had been returned once already since there were all kinds of rusting funky spots in those usual suspect areas...
This forum is a life saver... thanks again
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