Failed rear break bleed.

[Clay-Goose-Davis]

I bled my breaks following the how to. Not close enough I guess. When I went to pump them up after I was done it was nothing but slack for 25 pumps. Turned the key on, 25 more pumps. Check the break fluid and it’s empty:/ feeling very foolish. 
What’s the right thing to do from here? Bleed all four?
 

[Clay-Goose-Davis]

To clarify, the break pedal wasn’t totally slack while I pumped it up, just too much to feel right.

now when the cars off it feels normal. And with the key turned. But when I start the car the pedal goes to the floor when only lightly pressed

[2seater]

I am a little confused by the term, "pumped them up"? The rear brakes are bled using the brake pump and having the brake pedal pushed a small amount to allow the fluid through. It is very important to keep fluid in the reservoir so a helper becomes very important for being certain the reservoir doesn't run dry. If that happened, there will be air in the system and possibly air locked the pump. You almost have to start over. 

[Clay-Goose-Davis]

I had a terrible time putting my new struts in and was up all night battling them. I disconnected the break hoses to have an easier angle of access hammering a screw driver into the strut clamp to open them up. By the time I got to bleeding the breaks it was 4am and raining. I was too tired to be learning how the brake system works but I tried.

This is the last portion of text on the how to guide, and what I think I misunderstood. 

“When you are done check the high and low marks on the reservoir. After the system pump and motor has run and the lights are out the level should be at the low mark. When you have pumped the brakes with the key off 25 times the level will be at the high mark. Add or remove fluid if necessary to bring the fluid to the correct level.”

 

I did the 25 pump step at the end instead of the beginning.

Edited September 27, 2023 by Clay-Goose-Davis

[Clay-Goose-Davis]

8 hours ago, 2seater said:If that happened, there will be air in the system and possibly air locked the pump. You almost have to start over. 

I have a 91, so no accumulator. No need to pump pedal to relieve pressure at all then. Dumb mistake.

It’s totally my fault I didn’t read close enough but I feel it’d be useful to have a separate how-to/info for the Bosch Break system. I’m having a hard time finding information on it.

Ive been looking into it now but still am unsure of a few things and don’t have my car at home to go look at.

Is there still a pump in the Bosch system? I read it’s a conventional vacuum system and I know some are connected to the engine. Any info on the Bosch system or a link to a related thread would be much appreciated 

[Ronnie]

22 minutes ago, Clay-Goose-Davis said:

Is there still a pump in the Bosch system? I read it’s a conventional vacuum system and I know some are connected to the engine.

No brake pump on a '91 model. To my knowledge it's just a standard dual master cylinder with a vacuum booster. The booster has a hose that connects it to the intake manifold. The Bosch ABS unit is a separate system connected to the master cylinder. It controls the braking to each wheel when it detects a wheel is locking up during a hard braking or on wet pavement.  Even though it may use different brand parts, my GMC pickup has basically the same system.

[2seater]

I had my head somewhere I won't mention and I certainly missed the fact it is a 91😖 As mentioned above, it is a completely different system and I believe conventional bleeding methods will work just fine. My bad.