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#1 |
Registered User
Join Date: Dec 2012
Location: louisville, ky
Posts: 480
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Why is brake fluid puking out the resevoir cap??
I put this truck together and have been driving it for 4 months. Put about 3000 miles on it and today the brake pedal went to the floor. The front resevoir was empty so i filled it and reinstalled the cap. checked and no leaks at lines, hoses, or calipers. Pump the brakes and fluid leaks out around the resevoir cap. why does it spit out and how did it run it dry? this is the setup i have, should i ditch it and buy a whole cpp unit?
http://www.ebay.com/itm/1967-1972-ch...0c5284&vxp=mtr |
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#2 |
Registered User
Join Date: Dec 2007
Location: Nanaimo B.C.
Posts: 604
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Re: Why is brake fluid puking out the resevoir cap??
check the brake drums the cylinders may have faild
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I was hooked on these trucks since 1982 when I drove my budys fathers 1968 Custum GMC 396 automatic dana 60 rear with a power lock diff what a ride more fun then we will we can ever tell!! |
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#3 |
Registered User
Join Date: Feb 2013
Location: Upland, Calif
Posts: 698
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Re: Why is brake fluid puking out the resevoir cap??
The cap is vented, 1 or 2 little holes, probably at the bail wire passage thru the metal cap. Check if they're plugged. Or the cap is a loose fit. You can bend the L tang slightly to tighten the cap
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1957 CHEVY 1/2 TON SHORT BED 1940 FORD 1/2 TON SHORT BED |
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#4 |
Registered User
Join Date: Jul 2011
Location: Des Moines, Iowa
Posts: 3,016
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Re: Why is brake fluid puking out the resevoir cap??
Sounds like you are positive there are no leaks, anywhere. How did bleeding the lines go after you installed? Did you remember to bleed the MC too?
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project: "my happy mess" |
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#5 |
Who Changed This?
![]() Join Date: Jan 2013
Location: Simi Valley, CA
Posts: 10,435
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Re: Why is brake fluid puking out the resevoir cap??
You need to bleed the brakes, there is air in the lines. Then you need to check for where the leak is, even if you don't believe you have one. If you have front drums, you for sure have a leak. If you have disc brakes, it is possible that the pads are so worn that the cylinder got that low. If you don't see fluid leaks at the flexible brake lines or wheel cylinders, pull the master away from the booster and see if there is fluid leaking out the back of the master.
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~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA |
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#6 |
Registered User
Join Date: Dec 2012
Location: louisville, ky
Posts: 480
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Re: Why is brake fluid puking out the resevoir cap??
There are no leaks, and the reservoir for the rear brakes was still full. I have worked on cars for a long time and never seen one spit all the fluid out of the cap
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#7 |
Registered User
Join Date: Dec 2012
Location: louisville, ky
Posts: 480
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Re: Why is brake fluid puking out the resevoir cap??
the brakes bleed out fine, there are no leaks anywhere else. I guess i need to try to bend the cap or the hold downs to get it to fit tighter. The seal on the cap looks ok. After bleeding the brakes and putting the cap back on when i pump the pedal it pushes fluid out of the cap.
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#8 |
Moderator
![]() Join Date: May 2007
Location: Southern Cal
Posts: 20,005
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Re: Why is brake fluid puking out the resevoir cap??
Lightly sanding the mating surface of the master cylinder has worked for me in the past when I had this same problem. If not perfectly smooth they will leak.
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1972 C/10 Cheyenne Super SWB. Restored, loaded, slammed. 1968 C/10 50th Anniversary LWB. Unrestored, stock, daily driver/work truck. RIP ElJay RIP 67ChevyRedneck RIP Grumpy Old Man |
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#9 |
Registered User
Join Date: Jul 2011
Location: Des Moines, Iowa
Posts: 3,016
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Re: Why is brake fluid puking out the resevoir cap??
You keep saying the 'brakes' bled out fine. Did you bleed the master cylinder?
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project: "my happy mess" |
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#10 |
Registered User
Join Date: Dec 2012
Location: louisville, ky
Posts: 480
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Re: Why is brake fluid puking out the resevoir cap??
I bleed out of the calipers and wheel cylinders till there was no air coming out. ALso i just built the truck. Literally every brake component was new in 2013, hoses, calipers, wheel cylinders, master, prop valve, booster. I have driven approx 3000 miles with no problems untill today. I will mess with it tomorrow to try to get the cap to seal, i think that is my main problem.
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#11 |
Registered User
Join Date: Feb 2008
Location: Tacoma Washington
Posts: 890
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Re: Why is brake fluid puking out the resevoir cap??
Since ran the master down you should probably bleed it. I believe that is what 68 (Mr. Basket?) is asking.
Jeff
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I know a guy who's addicted to brake fluid. He says he can stop any time. 72 K10 396 75 Cj5 MPI 350 Chev 67 Chevelle 396, 4 speed 74 FXE 08 Tahoe Last edited by imjeff; 04-18-2014 at 10:57 PM. Reason: Spelling |
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#12 |
Registered User
Join Date: Jul 2011
Location: Des Moines, Iowa
Posts: 3,016
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Re: Why is brake fluid puking out the resevoir cap??
You MUST bleed a new Master Cylinder. That could possibly (?) be causing your issue (I've never not bled a new master cylinder so I don't know first hand). Air in the Master Cylinder finally displaced (or escaped) and your pedal hits the floor. After bleeding the Master Cylinder, you'll need to go back and re-bleed the lines again. Since you've already got the Master Cylinder and booster installed on the truck, no need to remove it. Remove the lines and bleed the master cylinder as shown in this video - only you'll use your brake pedal instead. It'd help if you had another person. The process shown in this video applies.
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project: "my happy mess" Last edited by litew8; 04-18-2014 at 11:14 PM. |
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#13 |
Senior Member
![]() Join Date: Sep 2005
Location: Lewisville, Nc
Posts: 10,234
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Re: Why is brake fluid puking out the resevoir cap??
I dont bench bled mine anymore specialy since the last one i bought didnot come with plugs or bleeders bled mine o the truck no issuses.
Is it oppable the master cylinder has a leak internally you push brakes it blews fuild out the oother chamber
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David fuller Ase Certified Mechanic Click here to help support our board!! 1971 Chevy c-10 under going a 4.8l LSx swap Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=421305 2007 Honda Accord my daily 145kmiles 2002 Honda Accord 4 door With 330k(sisters car) 2005 toyota Avalon 228k( brothers car) 2002 Sububran 5.3 245k 2000 Tahoe 5.3l 378 General manager for Marco's Carwash & lube |
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#14 |
Senior Member
![]() Join Date: Sep 2005
Location: Lewisville, Nc
Posts: 10,234
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Re: Why is brake fluid puking out the resevoir cap??
I dont bench bled mine anymore specialy since the last one i bought didnot come with plugs or bleeders bled mine o the truck no issuses.
Is it oppable the master cylinder has a leak internally you push brakes it blews fuild out the oother chamber
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David fuller Ase Certified Mechanic Click here to help support our board!! 1971 Chevy c-10 under going a 4.8l LSx swap Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=421305 2007 Honda Accord my daily 145kmiles 2002 Honda Accord 4 door With 330k(sisters car) 2005 toyota Avalon 228k( brothers car) 2002 Sububran 5.3 245k 2000 Tahoe 5.3l 378 General manager for Marco's Carwash & lube |
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#15 |
Registered User
Join Date: Jul 2011
Location: Des Moines, Iowa
Posts: 3,016
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Re: Why is brake fluid puking out the resevoir cap??
Either way, if he didn't bleed the master cylinder it needs to be done (always for new, and or if it emptied). The master cylinder itself could be defective, but he needs to bleed it, then all four wheels before being able to determine if the master cylinder is faulty. To the OP, buying a new master cylinder, think about it - there's no fluid - just air all up in it, which needs removed before installing. Not doing so will allow pockets of air to remain in the chamber. The video mentions it briefly - what happens when it isn't removed.
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#16 |
Registered User
Join Date: Jul 2011
Location: strausstown pa
Posts: 3,394
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Re: Why is brake fluid puking out the resevoir cap??
heres my 2 cents
i think with that much air in the lines would've been noticed right away not 4 months 3k mi. later. air bubbles allways travel up unless forced down. 3k mi. bounceing down the road any air would've made it up too the mc and the rubber in the cap would displace the escaped air in the system. i would fill the master and bleed the entire system and be positive there is no leaks ANYWHERE!(if its non power be sure too check in the cab behind the pedal). if there is no leaks... i would replace the master and be absolutely sure the brake push rod is adjusted too the proper length. it could be a lil' long and pushing the piston a lil' too far over the past few months eventually blowing or hanging up the last in line seal on the piston hence the reason fluid is presureizeing the resivior instead of the lines. also be sure the valve on the prop valve is centered again just my 2 cents
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81 camaro 355 4/spd 342 posi my first love ![]() 67 swb step 454/4spd ott 373 posi 4/7 drop. 2000 s10 zr2 little blue truck that never gets stuck. '74 heald super bronc vt8. tecumseh powered moon rover. |
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#17 |
Registered User
Join Date: Jul 2011
Location: Des Moines, Iowa
Posts: 3,016
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Re: Why is brake fluid puking out the resevoir cap??
Bleeding the lines and bleeding the master cylinder are two different things. The master cylinder will not be bled properly by be bleeding the lines only. The air is trapped differently in the master cylinder and needs to be removed separately but first. This is a safety issue (having brakes working properly) so standard installation procedures must be followed. Luckily the brakes didn't go out while driving and cause harm to you or someone else.
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project: "my happy mess" |
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#18 |
Registered User
Join Date: Oct 2006
Location: Dundee, Oregon
Posts: 311
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Re: Why is brake fluid puking out the resevoir cap??
Your wasting your time bleeding that master cylinder. It has failed internally and is bypassing from one reservoir to the other. The obvious sign of this is one empty reservoir and the other is overflowing. No amount of bleeding will ever cause the reservoir to overflow.
Replacing that master cylinder with a quality and properly bench bleed unit is going to save you a lot of time and brake fluid. |
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#19 |
Registered User
Join Date: Jul 2011
Location: Des Moines, Iowa
Posts: 3,016
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Re: Why is brake fluid puking out the resevoir cap??
Overflowing? Where'd you read that
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project: "my happy mess" |
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#20 |
Account Suspended
Join Date: Oct 2013
Location: murfreesboro, tn
Posts: 109
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Re: Why is brake fluid puking out the resevoir cap??
Where did you NOT read that? That's what this thread is about.
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#21 |
Registered User
Join Date: Jul 2011
Location: Des Moines, Iowa
Posts: 3,016
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Re: Why is brake fluid puking out the resevoir cap??
crap, my bad wrong thread
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project: "my happy mess" |
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#22 |
Account Suspended
Join Date: Oct 2013
Location: murfreesboro, tn
Posts: 109
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Re: Why is brake fluid puking out the resevoir cap??
I had to laugh.
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#23 |
Registered User
Join Date: Jul 2011
Location: Des Moines, Iowa
Posts: 3,016
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Re: Why is brake fluid puking out the resevoir cap??
Any update on this?
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project: "my happy mess" |
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#24 |
Registered User
Join Date: Oct 2010
Location: Vancouver BC
Posts: 57
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Re: Why is brake fluid puking out the resevoir cap??
68shortfleet has it right I think.
"The obvious sign of this is one empty reservoir and the other is overflowing. It has failed internally and is bypassing from one reservoir to the other. " |
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#25 |
Registered User
![]() Join Date: Feb 2014
Location: West Iowa
Posts: 1,106
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Re: Why is brake fluid puking out the resevoir cap??
If these are vacuum assisted power brakes, the reservoir went dry with no obviuos leak, and now it is puking fluid. I would strongly look at the vac container. I suspect it has a hole internally, hence the loss of fluid with no leak. And now that you have put more fluid in it when you press on the brakes it pukes out the master cylinder. Bruce
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