Bleeding Brakes - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Roadhammer · 10-23-2009, 10:41 AM

Searched a little and didnt find anyine with the same issue.

Im trying to bleed my newly run brakes. 1979 disks and crossmember in front and old drums in back. 1979 dual master cylinder up front.

Ive had success in the back both old rusty valves opened and allow brake fluid to exit and even squirt out so they work, but the front valves were full of rust so i cleaned them out so they could breath and they still wont let any fluid come out. as far as i can tell i have had no fluid leave the front cylinder resevior at all. Dont know why this would be. I installed all new lines for the front brakes(used old hoses but they worked fine before i drove the 1979 600 miles home with those brakelines.

The only think i can think of is that the proportioning valve might be cutting off the flow but i only have a ver limitted knowledge of how those work.

any ideas?

Jory

Roadhammer · 10-23-2009, 11:36 AM

Found it button on the front needs to be held in ...thanks anyway..

someone can delete this if they like...

Jory

bubba327 · 10-23-2009, 02:26 PM

First; Are you using a new master cylinder? if so, did you bench bleed it before installing it?

Roadhammer · 10-23-2009, 03:41 PM

Quote:

Originally Posted by bubba327

First; Are you using a new master cylinder? if so, did you bench bleed it before installing it?

The master cylinder and booster are out of the 1979 doner truck.

Explain bench bleed?

That might give you an idea of what im workin with.

Jory

bubba327 · 10-24-2009, 12:58 AM

Bench bleeding is removing all the air from the master cylinder before you install it in the truck, Clamp the master cylinder in a vise, pipe each outlet line back into the master cylinder side that it started from,(plastic tubing works fine) And gently push in with a dowel or phillips screwdriver "priming " the master cylinder and removing all the air from it first. 15 -50 strokes and until no bubbles are left. When you put it in the truck, you can bleed the lines but DO NOT let the master go dry or you have to start over.
Good luck It is not hard, go slow and be patient. Sometimes bleeding brakes takes awhile.

TjBlueRusty · 11-09-2009, 03:35 PM

Did you get your front brakes bled? If so what did you do? I'm having the same problem on a 75 C10.

I replaced the MC, front calipers, rear cylinders, and the rear steel lines starting at the front of the bed. I get fluid coming out of the rear cylinders but nothing from the front. I did bench bleed the MC before installing.

Roadhammer · 11-09-2009, 03:40 PM

Quote:

Originally Posted by TjBlueRusty

Did you get your front brakes bled? If so what did you do? I'm having the same problem on a 75 C10.

I replaced the MC, front calipers, rear cylinders, and the rear steel lines starting at the front of the bed. I get fluid coming out of the rear cylinders but nothing from the front. I did bench bleed the MC before installing.

The problem was that the bump stop for the brake pedal was holding it to far forward so that the master cylinder was not clearing the reseviour inlet. Blocking the flow of the fluid in the front chamber. so when i let the brake pedal come back far enough the cylinder came back and the fluid was able to flow down into the front line. Once the pressure was off the brake they bled within minutes.

Jory

TjBlueRusty · 11-12-2009, 11:41 AM

Thanks Jory. I'm thinking mine has a different problem. I get fluid when I crack open the line coming off the MC for the front brakes but nothing at the calipers.

19GMC63 · 11-12-2009, 12:21 PM

TjBlue,
Did you replace your front rubber hoses?

TjBlueRusty · 11-12-2009, 04:06 PM

I have not replaced the front hoses. I've read different threads to where that fixed front bleeding issues and maybe that's also my problem.

I have loaded a small oil can with brake fluid and connected it to the opened right front bleeder valve. I was able to pump fluid into the line but no air bubbles nor did the fluid level change in the MC and there are no leaks. I'm wondering if the proportional valve could have the front blocked off? It looks tough to get to on this 75.

Thanks for the help Andrew. Sorry Jory, I didn't mean to Hi-Jack your thread.

Tj

Roadhammer · 11-12-2009, 06:31 PM

Thanks for the help Andrew. Sorry Jory, I didn't mean to Hi-Jack your thread.

Tj[/QUOTE]

Dont worry about it i fixed my problem...your thread now. LOL

Jory

10-23-2009, 10:41 AM	#1
Roadhammer Registered User Join Date: Aug 2009 Location: Coaldale Alberta Posts: 174	Bleeding Brakes Searched a little and didnt find anyine with the same issue. Im trying to bleed my newly run brakes. 1979 disks and crossmember in front and old drums in back. 1979 dual master cylinder up front. Ive had success in the back both old rusty valves opened and allow brake fluid to exit and even squirt out so they work, but the front valves were full of rust so i cleaned them out so they could breath and they still wont let any fluid come out. as far as i can tell i have had no fluid leave the front cylinder resevior at all. Dont know why this would be. I installed all new lines for the front brakes(used old hoses but they worked fine before i drove the 1979 600 miles home with those brakelines. The only think i can think of is that the proportioning valve might be cutting off the flow but i only have a ver limitted knowledge of how those work. any ideas? Jory

10-23-2009, 11:36 AM	#2
Roadhammer Registered User Join Date: Aug 2009 Location: Coaldale Alberta Posts: 174	Re: Bleeding Brakes Found it button on the front needs to be held in ...thanks anyway.. someone can delete this if they like... Jory

10-23-2009, 02:26 PM	#3
bubba327 HOW long until spring?? Join Date: Mar 2009 Location: Star Idaho Posts: 1,413	Re: Bleeding Brakes First; Are you using a new master cylinder? if so, did you bench bleed it before installing it? __________________ 69 chevelle convertible 71-C-10 short-wide and low 64 C-10 custom shortbox "Bubba"s Recycling project"

10-24-2009, 12:58 AM	#5
bubba327 HOW long until spring?? Join Date: Mar 2009 Location: Star Idaho Posts: 1,413	Re: Bleeding Brakes Bench bleeding is removing all the air from the master cylinder before you install it in the truck, Clamp the master cylinder in a vise, pipe each outlet line back into the master cylinder side that it started from,(plastic tubing works fine) And gently push in with a dowel or phillips screwdriver "priming " the master cylinder and removing all the air from it first. 15 -50 strokes and until no bubbles are left. When you put it in the truck, you can bleed the lines but DO NOT let the master go dry or you have to start over. Good luck It is not hard, go slow and be patient. Sometimes bleeding brakes takes awhile. __________________ 69 chevelle convertible 71-C-10 short-wide and low 64 C-10 custom shortbox "Bubba"s Recycling project"

11-09-2009, 03:35 PM	#6
TjBlueRusty Registered User Join Date: Jun 2009 Location: Shawnee, KS Posts: 10	Re: Bleeding Brakes Did you get your front brakes bled? If so what did you do? I'm having the same problem on a 75 C10. I replaced the MC, front calipers, rear cylinders, and the rear steel lines starting at the front of the bed. I get fluid coming out of the rear cylinders but nothing from the front. I did bench bleed the MC before installing.

11-12-2009, 11:41 AM	#8
TjBlueRusty Registered User Join Date: Jun 2009 Location: Shawnee, KS Posts: 10	Re: Bleeding Brakes Thanks Jory. I'm thinking mine has a different problem. I get fluid when I crack open the line coming off the MC for the front brakes but nothing at the calipers.

11-12-2009, 12:21 PM	#9
19GMC63 Registered User Join Date: Nov 2006 Location: Nashville, TN Posts: 1,510	Re: Bleeding Brakes TjBlue, Did you replace your front rubber hoses?

11-12-2009, 04:06 PM	#10
TjBlueRusty Registered User Join Date: Jun 2009 Location: Shawnee, KS Posts: 10	Re: Bleeding Brakes I have not replaced the front hoses. I've read different threads to where that fixed front bleeding issues and maybe that's also my problem. I have loaded a small oil can with brake fluid and connected it to the opened right front bleeder valve. I was able to pump fluid into the line but no air bubbles nor did the fluid level change in the MC and there are no leaks. I'm wondering if the proportional valve could have the front blocked off? It looks tough to get to on this 75. Thanks for the help Andrew. Sorry Jory, I didn't mean to Hi-Jack your thread. Tj

11-12-2009, 06:31 PM	#11
Roadhammer Registered User Join Date: Aug 2009 Location: Coaldale Alberta Posts: 174	Re: Bleeding Brakes Thanks for the help Andrew. Sorry Jory, I didn't mean to Hi-Jack your thread. Tj[/QUOTE] Dont worry about it i fixed my problem...your thread now. LOL Jory



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