Hey everyone,
I’ve been working on rebuilding the brake system on my 1988 Firebird Trans Am GTA (5.7L, front disc/rear disc), and I have been struggling with bleeding.

What I’ve Done:

• Replaced all brake lines
• Installed new brake hoses – steel braided in the front, rubber for the rear pass and the tee (there is no hose for the rear driver’s side on this car)
• Installed new calipers, brake pads, banjo bolts (should all be stock)
• Bled the master cylinder

The problem:

• Front brakes work, but they build excessive pressure after a few pedal pumps — pedal gets rock hard, and rotors become very hard to turn.
• Rear brakes will not bleed. Nothing comes out of the bleeder valves, not even air.
• When I unscrew the banjo bolt and press the brake, fluid comes out, however when I screw it into the caliper, nothing comes out of the bleeder. This appears to be a problem with the banjo bolt, however, I tested this by leaving the brake hose and banjo bolt screwed in, removing the brake line from the hose, and blowing air through the bleeder – it came out of the end of the hose meaning that the hose and banjo bolt are fine.
• Basically, if I hook everything up (line → hose → caliper), fluid stops flowing at the bleeder.
• Even with new banjo bolts, confirmed open passages, and some (if minimal) flow, both rear calipers don’t receive fluid.
• I’ve checked the proportioning valve and fluid does come from the rear outlet on the valve when pedal is pressed and the line is slightly unscrewed.

What I’m Wondering:

• Is it possible there’s still air in the master cylinder affecting the rear circuit?
• Could the proportioning valve still be limiting flow, even if fluid is exiting the rear port?
• is it possible that there is just not enough flow to enter the caliper? What if I pour fluid through the bleeder?

Any thoughts or guidance would be greatly appreciated. Not super experienced but I’ve spent a lot of time diagnosing this and I’m just about out of ideas. Thanks in advance!

 

https://ebay.us/m/65fuEQ

 

Did the master run dry at some point? If so, might need a 'bench' bleed. Double check are the calipers installed with the bleeder screws facing up?

 

Hmmmm, What does this do? Is this a way to pressure bleed the brakes?

 

when you have a lot of air in the lines this prevents the proportioning valve from moving and stopping flow. You can use it pressure or vacuum bleeding.

 

That is cool. I've wanted to pressure bleed the system, but don't trust the gadget with chains that is sold to hold while doing so.

 

Once you get the tool that TunedPerf shared, you can use the master as your "pressure bleeder". Simply open all 4 bleeders, ensure the reservoir is full and cap it loosely so it doesn't "fountain" all over under the hood, then simply pump the pedal until you get fluid shooting from the bleeders at all 4 corners. If one corner fails to produce fluid, close it's companion and pump again until you get copious results. Finally, open teh bleeders again, let it gravity bleed for about 30 seconds or so (until you get no more air from the bleeders), then close 'em up, top the res and you're done. Easy Button.

 

Not quite following you Tom, When I pressure bleed, I pump pressure into a sealed master cylinder. No need to pump brake pedals at all. Not for a car w/o ABS anyway.

Pic of the equipment:
https://www.bimmerfest.com/attachmen...60-jpg.881061/
https://www.bimmerfest.com/attachmen...62-jpg.881065/

The general procedure is:

1. Fill reservoir.
2. Pressurize brake bleeder
3. Open one caliper bleeder valve, pressure from brake bleeder pushes fluid out, no brake pumping needed, just maintain pressure and fluid
4. Bleed until no air bubbles.
5. Close bleed valve
Repeat steps 1 - 5 at all four corners, one at a time. Starting with passenger side rear, driver rear, passenger front, driver front. Are we talking about the same thing?

 

Right....the key component there is you already have....the pressure bleeder tool. The pedal pumping is in lieu of that...NOT in conjunction with it. I never mentioned a pressure bleeder. TunedPerf shared a link to a centering tool for the prop valve (handy looking, but I've never needed one). While he did also mention pressure (or vacuum bleeding), note that I said:

...meaning, in lieu of a pressure or vacuum bleeder. The Master and your foot, becomes your "pressure" bleeder and it makes way, WAY more pressure and flow than a pressure bleeder can or will. Good for #3, below....

It's quite likely that most people who're posing about brake bleeding issues, probably don't have a pressure bleeder or a vacuum bleeder. Most people who have those tools, likely have experience bleeding (why they bought the tool), and have the knowledge and ability to work through bleeding issues, and are not posting on here, threads like, "Bleeding Rear Brakes Doesn't work".

SO, the pedal pumping w/open bleeders does several things for inexperienced (and experienced) people, who don't have fancy tools (and even those of us who do have 'em):
1. Saves them $$$ on tools they don't need.
2. Gets the system bled, including the MC, all the way out to the calipers
3. Forces any "smeg" in poorly maintained brake systems, through the system and out the bleeders ensuring all lines/hoses/fittings and orifices are free and clear to properly flow brake fluid...which = easy gravity bleeding then, and into the future.
4. Gets it done FAST. Teaching a tech of mine, I bled an entire system (including ABS and new MC) from empty to bled in <10 min. No $pecial tools. A wrench and my foot.

So for people who don't do this for a living....and even people who do, this is a way to not buy and then have to store a tool, and still get the same results and get 'em FAST.

 

For context, on the above, I should add that I've been a tech and the boss of techs for over 35 years. Also, I'm salaried, so the faster I can get work done, the sooner I can go home. Lastly? I'm lazy! I don't want to do things the slow way, when I can get 'em done, the FAST way, and that's how I roll, in the shop, and when teaching my techs in the shop. Thus, I'm always looking for faster/easier/better ways to get the same results.

The pedal pumping was something that I tried and found to work awesome, ~30 years ago when regularly bleeding brake systems on '90's F250's in a fleet. Often, those trucks wouldn't flow brake fluid on one or even both of the rear brakes, and some times on a front brake, too...as I'd try to gravity bleed them. At the time, I didn't have a pressure or vacuum bleeder...and I was PO, so I didn't want to buy one either. I also didn't want to have to ask other techs in that shop to stop what they were doing and help me pedal pump while I opened and closed bleeders over and over. F-THAT! Although fearful of "adding air into the system" -from what I'd learned in auto/tech skool, out of frustration and aware of the power potential of the MC, I closed all but the problem bleeder(s) and hammered the brake pedal multiple times. "Smeg" was cleared immediately and brake fluid shot from the problem bleeder like Old Faithful and to my delight, typical gravity bleeding commenced w/in seconds following my last pedal pump. Sweet!

So there is context; 30+ years of doing it, no tools needed. Push fluid through the system w/the MC and your foot....gravity bleed for a minute to finish off the calipers and/or wheel cylinders, done. t's a great method for the DIY'er at home who likely doesn't have the bleeding assist tools.

 

Sorry Tom, thought you were answering my question, can I use this to pressure bleed our 3rd Gens? I'm no professional, just a guy who keeps trying until he figures it out. The garage is my sanctuary where I get peace. I usually like to be there by myself when working on cars. That means I like using pressure bleeders for pushing fresh brake fluid thru the lines. Its super easy if the car is setup to do so. And, just as important to me, a one man job. I'm still not sure how this device can be used as a pressure bleed system. I'm guessing you can get an attachment for it, and hook it up to a (Insert brand here) Pressure Bleeder. But not sure where I would obtain this attachment.

 

I have used speed bleeders for a number of years. Works good. I have that tool Tuned performance posted but I forgot to use it the last time I bled my brakes. Speed bleeders have a check inside that closes when you let off the brake pedal. It also has thread sealant on the threads to keep air from being sucked in. When all air has been pushed out, simply close the bleeder and your done.

Fred

 

I know this is coming up on a year, but to put "my money where my mouth is", so to speak...

Just handled this, this past weekend with my '96 Silverado with rear drum brakes; opened the front bleeders, they started flowing immediately. Opened the rears, Nothing. Zero flow from either side in the rear. Removed the rear bleeders, still nothing, proving that they weren't plugged/causing the problem.
Closed the front bleeders, pumped the brake aggressively 3 or 4 times, walked around to the back of the truck and the rears were flowing good already. Put the bleeders in and let it run through them for another 30 seconds or so, closed 'em up. Easy Button.