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73-87 Chevy _ GMC Trucks => Brakes, Frame, Steering & Suspension => Brakes and Braking Systems => Topic started by: flyboy9994 on January 19, 2007, 09:54:00 am

Title: Brake Bleeding
Post by: flyboy9994 on January 19, 2007, 09:54:00 am

Hey All

Been awhile since I've been here. Anyway, what started with a simple "paint the engine bay" project pretty much ended up with the whole front end coming off, entire front suspension re-build, new crate engine, new transmission all new brakes etc etc... Jeeezzz what have I gotten myself into anyway??

My question involves bleeding an entirely new brake system. I'm replacing every single component from the master cylinder all the way out to each wheel with new stainless brake lines, new proportioning valve, front calipers etc... The whole works. I have bled brakes several times using the old "pump the pedal" routine but there has to be a better way. Does anybody have a good technique for bleeding a completely dry system from scratch??

Title: Re: Brake Bleeding
Post by: Blazin on January 19, 2007, 10:22:00 am

Gravity bleed first, Open all the bleeders and leave the top off the cylinder. Let it run through. Then put some brake fluid in four quart containers and run a soft rubber hose down from each bleeder that fits very snug onto the bleeder screw. Make sure the end is submreged a good amout in each container of fluid. Then get in and slowly depress and release the pedal until it comes up hard. After a bit of road time I would recomend doing it again just for sure.  

Title: Re: Brake Bleeding
Post by: flyboy9994 on January 19, 2007, 09:42:00 pm

O.K. Thanks Blazin

That makes a lot of sense. As far as the gravity bleed goes, I understand that I just simply fill the master cylinder and let the fluid work it's way through the brake lines to each wheel correct? Should I open all four bleeder screws at once during the gravity bleed?

Title: brake bleeding
Post by: Mr Diesel on January 19, 2007, 10:07:00 pm

Fastest and easiest way:

-Attach tight-fitting rubber hose to bleeder nipple and loosen the nipple.  
-Route hose upward from the nipple, then down into a container to collect the waste. (by having a section of hose higher than the nipple air will rise upward and the heavier fluid will sink down, eliminating problems with air flowing back into the lines as you bleed)
-Remove master cylinder cover and make sure there is plenty of fluid
-Get in truck and push brake pedal, checking the master cylinder level every 5-10 pushes.
-Once you have flushed the line, just tighten the nipple and move on to the next one wheel.

Entire brake system can be bled in only a few minutes

- Mr Diesel
'76 C30 Crew 6.2

Title: Master
Post by: VileZambonie on January 20, 2007, 10:43:00 am

You all missed one critical step here...

Bench Bleed the master cylinder first. You can gravity bleed til the cows come home but you'll never get the air trapped in the master out without first bleeding the master.

THIS PROCEDURE CAN BE PERFORMED WITH MASTER CYLINDER ON OR OFF VEHICLE .



Disconnect brake lines at master cylinder, if necessary.
Connect suitable lengths of brake lines to master cylinder and immerse other ends of lines in master cylinder reservoirs.
Apply master cylinder pushrod or brake pedal with full strokes until air bubbles have disappeared in reservoirs. It may require 20-30 applications to fully eliminate air bubbles.
Remove bleeding lines from master cylinder, then install master cylinder on vehicle, if necessary, and connect brake lines.
Fill the reservoir. Normal bleeding procedures should be followed after the master cylinder is installed.

Manual Bleeding


If vehicle is equipped with power brakes, remove vacuum reserve by applying brakes several times with engine off.
Fill master cylinder reservoirs with suitable brake fluid. Be sure to always keep master cylinder reservoirs at least half full during entire bleeding procedure.
If master cylinder is suspected to have air in the bore, it must be bled first, as follows:
Disconnect forward brake pipe connection at master cylinder.
Allow brake fluid to fill master cylinder bore until it begins to flow from forward pipe connector port.
Connect and tighten forward brake pipe at master cylinder.
Depress brake pedal slowly one time and hold, then loosen forward brake pipe connection at master cylinder to purge air from bore. Tighten connection, then release brake pedal slowly. Wait 15 seconds, then repeat sequence, including 15 second wait, until all air is purged from bore.
Bleed rear bore of master cylinder as front bore was bled.
Bleed right rear brake as follows:
Depress brake pedal slowly one time and hold.
Loosen bleeder valve to purge air from brake, then tighten bleeder valve and slowly release pedal.
Wait 15 seconds, then repeat sequence, including 15 second wait, until all air is purged.
Bleed left rear, right front, and left front brakes, in that order, using same method as for right rear brake.
Check brake operation and ensure pedal is firm. Also check master cylinder fluid level and add fluid as necessary.
Turn off brake warning light by applying moderate pressure to brake pedal several times.
Road test vehicle.

Installing Pressure Bleeder Adapter


 



Pressure Bleeding


Loosen, then slightly retighten bleeder valves at all four wheels. Repair any broken, stripped or frozen valves at this time.
Using a diaphragm type pressure bleeder, install suitable bleeder adapter to master cylinder, Fig. 1.
Charge bleeder ball to 20-25 psi, then depress and hold valve stem on combination valve.
Connect pressure bleeder line to adapter.
Open line valve on pressure bleeder, then depress bleed-off valve on adapter until a small amount of brake fluid is released.
Raise and support vehicle.
Bleed right rear, left rear, right front and left front brakes, in that order.
Place transparent tube over bleeder valve, then allow tube to hang down into transparent container. Ensure end of tube is submerged in clean brake fluid.
Open bleeder valve 1/2 to 3/4 turn and allow fluid to flow into container until all air is purged from line.
Flushing Hydraulic System
If brake fluid is old, rusty or contaminated, or whenever new parts are installed in the hydraulic system, the system must be flushed. Bleed brakes, allowing at least one quart of clean brake fluid to pass through system. Any rubber parts in hydraulic system which were exposed to contaminated fluid must be replaced.

Title: Re: Master
Post by: Blazin on January 20, 2007, 10:59:00 am

Oh yeah I forgot that master cylinder bleed! I useually do all four wheels at the same time.