Brake Bleeding Problem (long) - The 1947 - Present Chevrolet & GMC Truck Message Board Network

the-wreck · 09-23-2002, 07:36 AM

Hello
Well Im putting my 69 together and this is all thats holding me up from DRIVING IT! It has 72 disc brakes on it with all new parts including lines.
Im having trouble getting a pedal. I think I have front brakes but Im not geting a good amount of fluid out of the rears (a little air too).
I have tried a few things. Both bleeders open and let them siphon a while. Both bleeders open with hoses into jars of brake fluid and pump them. Also, the usuall pump and open. Still no decent shot of fluid yet. I suspect theres still a lot of air somewhere in there.
Any ideas?
Thanks

JimKshortstep4x4 · 09-23-2002, 08:47 AM

Bleeding the brakes on these trucks can be frustrating! I would go back to the proportioning valve and bleed the front line into the master cylinder using a length of tubing. Then do the same for the rear line. This will bleed the master cylinder and the proportioning valve. Then rebleed the fronts and the rears. If this does not work, then there is probably a leak somewhere that you cannot see. (I assume that you have checked). Also, the rear brakes need to be adjusted or the shoe movement can be great enough to give you a problem.

Jim

Gordo · 09-23-2002, 05:07 PM

If this assembly is all new/used, be sure that the rod from your peddle assembly that goes into the master/booster isn't too long, because if it holds the piston within the master from returning ALL the way back you can have problems like you have now.

bobs409 · 09-24-2002, 08:38 AM

I don't know the exact science of it as most of my vehicles have drum brakes but there is a button on the proportioning valve that your supposed to press in while bleeding brakes on a disc setup. I think you have to keep the button depressed while bleeding but not sure.

JimKshortstep4x4 · 09-24-2002, 09:22 AM

If you bleed the brakes as I described, you will know if the prop valve is giving a problem. We have not had a problem with the prop valve in bleeding but it could happen. Pumping gently when first bleeding will keep the valve from shifting. Also, there are prop valves that don't have an external button, so there is no way to shift the valve on those manually.

Jim

pickup6772 · 09-25-2002, 09:24 PM

I HAD THIS PROBLEM WITH A '72 PLYMOUTH FURY(BOY I MISS THAT TANK!!!). IT TURNED OUT TO BE A COLLAPSED REAR BRAKE HOSE.DO YOU KNOW WHAT IT WAS LIKE TRYING TO STOP 2 1/2 TONS OF AMERICAN STEEL???SO CHECK YOUR FRONT, AND REAR RUBBER BRAKE HOSES, AS THEY WILL COLLAPSE WHEN THEY GET OLD.
P.S THAT PLYMOUTH WAS GREAT FOR RUNNING OVER JAP WANNABE'S. YOU SHOULD HAVE SEEN THE LOOK ON SOME OF THOSE PUNK KIDS WHEN ALL THEY SAW WAS BUMPER COMING UP ON THEM, AND NOT SLOWING DOWN!!!!!!!!!!!!

adamls · 09-25-2002, 09:37 PM

If your master cylinder was new or dry before installing it then you should bleed the master cylinder on a bench before installing. If not it is almost impossible to completly bleed the air from the entire system. JimK had a good idea.

09-23-2002, 07:36 AM	#1
the-wreck Registered User Join Date: Sep 2001 Location: LI New York Posts: 159	Brake Bleeding Problem (long) Hello Well Im putting my 69 together and this is all thats holding me up from DRIVING IT! It has 72 disc brakes on it with all new parts including lines. Im having trouble getting a pedal. I think I have front brakes but Im not geting a good amount of fluid out of the rears (a little air too). I have tried a few things. Both bleeders open and let them siphon a while. Both bleeders open with hoses into jars of brake fluid and pump them. Also, the usuall pump and open. Still no decent shot of fluid yet. I suspect theres still a lot of air somewhere in there. Any ideas? Thanks

09-23-2002, 05:07 PM	#3
Gordo Registered User Join Date: Jan 2001 Location: Killingworth, CT. USA Posts: 3,378	If this assembly is all new/used, be sure that the rod from your peddle assembly that goes into the master/booster isn't too long, because if it holds the piston within the master from returning ALL the way back you can have problems like you have now. __________________ 1971 C10 swb stepside 350/700R4/3.73posi (retired as of 4/22/03) 1998 S10 short bed 2002 S10 Blazer 1942 Oldsmobile 1958 Massey Harris Pony 1951 Wife Killingworth, Connecticut May those who love us, love us, any of those who do not love us, may God turn their hearts. And if God is unable to turn their hearts, may he turn their ankles so we may know them by their limping. A man who works with his hands is a laborer; a man who works with his hands and his brain is a craftsman; but a man who works with his hands and his brain and his heart is an artist.

09-24-2002, 08:38 AM	#4
bobs409 1969 Custom 30 wrecker Join Date: Sep 2001 Location: Pottsville, Pa Posts: 2,611	I don't know the exact science of it as most of my vehicles have drum brakes but there is a button on the proportioning valve that your supposed to press in while bleeding brakes on a disc setup. I think you have to keep the button depressed while bleeding but not sure. __________________ Bob 63 Impala 283/PG/3.36 (under restoration) 66 Impala 327/PG/3.36 66 Chevelle SS 409/M22/3.55 69 Chevelle 307/PG/3.08 (future restoration) 69 C10 short stepside 454/TH350/3.73 69 Custom 30 tow truck 350/4 spd/4.10 (resto done, CRUISIN TIME!) 71 Cheyenne 20 fleetside 350/4 spd/4.10 71 Chevelle 6/PG/3.08 72 Chevelle 454/M21/4.10

09-25-2002, 09:37 PM	#7
adamls Gotta Startem Early Join Date: Oct 2001 Location: Amarillo, TX, USA Posts: 364	If your master cylinder was new or dry before installing it then you should bleed the master cylinder on a bench before installing. If not it is almost impossible to completly bleed the air from the entire system. JimK had a good idea. __________________ 67 SWB In Progress, one piece at a time, maybe 3 years I will be finished

09-23-2002, 08:47 AM	#2
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Bleeding the brakes on these trucks can be frustrating! I would go back to the proportioning valve and bleed the front line into the master cylinder using a length of tubing. Then do the same for the rear line. This will bleed the master cylinder and the proportioning valve. Then rebleed the fronts and the rears. If this does not work, then there is probably a leak somewhere that you cannot see. (I assume that you have checked). Also, the rear brakes need to be adjusted or the shoe movement can be great enough to give you a problem. Jim

09-24-2002, 09:22 AM	#5
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	If you bleed the brakes as I described, you will know if the prop valve is giving a problem. We have not had a problem with the prop valve in bleeding but it could happen. Pumping gently when first bleeding will keep the valve from shifting. Also, there are prop valves that don't have an external button, so there is no way to shift the valve on those manually. Jim

09-25-2002, 09:24 PM	#6
pickup6772 Registered User Join Date: Aug 2002 Location: MASTIC BEACH, long island, ny Posts: 362	I HAD THIS PROBLEM WITH A '72 PLYMOUTH FURY(BOY I MISS THAT TANK!!!). IT TURNED OUT TO BE A COLLAPSED REAR BRAKE HOSE.DO YOU KNOW WHAT IT WAS LIKE TRYING TO STOP 2 1/2 TONS OF AMERICAN STEEL???SO CHECK YOUR FRONT, AND REAR RUBBER BRAKE HOSES, AS THEY WILL COLLAPSE WHEN THEY GET OLD. P.S THAT PLYMOUTH WAS GREAT FOR RUNNING OVER JAP WANNABE'S. YOU SHOULD HAVE SEEN THE LOOK ON SOME OF THOSE PUNK KIDS WHEN ALL THEY SAW WAS BUMPER COMING UP ON THEM, AND NOT SLOWING DOWN!!!!!!!!!!!!



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