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#1 |
1972 Chevy Cheyenne Super
Join Date: Feb 2009
Location: Oklahoma City, OK
Posts: 302
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Brake Problems - Won't bleed, leaking out of master
The last piece of the puzzle before I can drive my truck home is the brakes. There seems to be a problem that we can't quite figure out. The lines won't bleed and they keep pumping fluid out of the rear of the master cylinder.
It's almost like there is damage inside the slave or master cylinder. Is this something that happens when these trucks have been sitting for too long? It was working great 4 years ago - but that was 4 years ago. Any help would be appreciated! Thanks. 1972 Chevy Super with Brake Booster
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-Clayton 1972 Cheyenne Super LWB 350 - farm truck restore project - twitter @oldgreen |
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#2 |
20' Daredevil (Ret)
![]() Join Date: May 2003
Location: Jefferson State
Posts: 13,627
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Re: Brake Problems - Won't bleed, leaking out of master
When you say it's pumping fluid out of the rear of the master cylinder, are you talking about where the plunger is -- where it attaches to the vacuum booster? That's definitely not right and you'll need to replace the master cylinder.
Still seems like you should get some fluid through the lines though, unless they're blocked. A more likely problem is the bleeders are plugged, which is common. If so, just remove them & clear the blockage (probably mud) then screw 'em back in.
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- Mike - 1972 K20 LWB 350/350/205 RIP El Jay |
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#3 |
Active Member
![]() Join Date: Jul 2007
Location: Centrally located between Houston, Austin and Waco. BCS area.
Posts: 7,947
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Re: Brake Problems - Won't bleed, leaking out of master
Yes, replace the master cylinder. Replace all three rubber lines if they are the original. They may look okay on the outside but the rubber will swell on the inside and prevent the fluid from passing through or restricts it. Not worth the trouble later on.
While you're at it, you may as well do a complete brake system rebuild. I spent a little over $200 but it was well worth the effort. All new shoes, springs kits, wheel brake cylinders, turned the drums and replaced all three rubber brake lines.
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68 GMC 250/3 speed Saginaw p/b p/s 69 Chevy 350/350 currently in pieces still lookin for a cab 06 Trailblazer I just want a vehicle that I can work on, that won't talk to me, leave error msgs or keep track of how I drive... |
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#4 |
I am a Referee of life.
Join Date: Jun 2000
Location: Greensboro N.C.
Posts: 13,993
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Re: Brake Problems - Won't bleed, leaking out of master
Also,flush all the fluid.It will absorb water and can cause rust in the new parts and will affect your braking.
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The 47-present Chevrolet and GMC Truck Message Board Network,it's owners,moderators,members,and associates of any type should not be held responsible for my opinion. You can't fix stupid,not even with duct tape. "My appearance is due to the fact that "GOD" does punish you for having too much fun!" Barrett-Jackson has perfected alchemy,they make rust into gold! "You can lead a horse to water but you can't saddle a duck" "Cleverly disguised as a 'Responsible Adult' "Sometimes your Knight in shining armor is just a retard in tinfoil" |
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#5 |
Registered User
Join Date: Jul 2007
Location: Salina, Kansas
Posts: 1,998
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Re: Brake Problems - Won't bleed, leaking out of master
master cylinders are $15 lifetime warrenty at a parts store... they are cheap cheap cheap
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1972 C-10...402/400..flowmaster 40 series 1967 Mustang 347 stroker/C-4 1966 Mustang 289/3-speed 2013 Mustang V6/6speed w/300 ponies I may be 23, but i sure do knows 67-72s are sexy! Its not MPG its smiles per gallon! build started 11/25/08 build thread: http://67-72chevytrucks.com/vboard/s....php?p=2993796 |
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#6 |
Registered User
Join Date: Jun 2011
Location: Richmond,Va
Posts: 2,934
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Re: Brake Problems - Won't bleed, leaking out of master
Leaking M/C's are bad....mmmk
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Nick Carter 1967 C10 Short bed Fleetside Project Cheap Thrills! 2WD C10 Modern/Performance Alignments Easiest Alignment Ever! |
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#7 | |
1972 Chevy Cheyenne Super
Join Date: Feb 2009
Location: Oklahoma City, OK
Posts: 302
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Re: Brake Problems - Won't bleed, leaking out of master
Quote:
Posted via Mobile Device
__________________
-Clayton 1972 Cheyenne Super LWB 350 - farm truck restore project - twitter @oldgreen |
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#8 |
1972 Chevy Cheyenne Super
Join Date: Feb 2009
Location: Oklahoma City, OK
Posts: 302
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Re: Brake Problems - Won't bleed, leaking out of master
We got fluid to all four brakes, we already cleaned the bleeders. It's just when you pump them up, it emptys the front bowl into the rear bowl and forces the fluid out the top. We think the splitter valve might be bad, under pressure it fails and sends the fluid back into the rear bowl of the master cylinder.
Posted via Mobile Device
__________________
-Clayton 1972 Cheyenne Super LWB 350 - farm truck restore project - twitter @oldgreen |
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#9 |
1972 Chevy Cheyenne Super
Join Date: Feb 2009
Location: Oklahoma City, OK
Posts: 302
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Re: Brake Problems - Won't bleed, leaking out of master
With a new master cylinder and help from this thread: http://67-72chevytrucks.com/vboard/s...d.php?t=241722 we were able to get the brakes working perfectly.
Thanks for your help everyone! ![]()
__________________
-Clayton 1972 Cheyenne Super LWB 350 - farm truck restore project - twitter @oldgreen |
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#10 |
Registered User
Join Date: Jul 2007
Location: Salina, Kansas
Posts: 1,998
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Re: Brake Problems - Won't bleed, leaking out of master
right on good to hear!
__________________
1972 C-10...402/400..flowmaster 40 series 1967 Mustang 347 stroker/C-4 1966 Mustang 289/3-speed 2013 Mustang V6/6speed w/300 ponies I may be 23, but i sure do knows 67-72s are sexy! Its not MPG its smiles per gallon! build started 11/25/08 build thread: http://67-72chevytrucks.com/vboard/s....php?p=2993796 |
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brake, brake booster, brake booster disc brakes |
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