No fluid to the back brakes

Tiny
TRAVELINGMAN5352
  • MEMBER
  • 1999 CHEVROLET TAHOE
  • V8
  • 4WD
  • AUTOMATIC
  • 195,000 MILES
I just replaced the vacuum booster and the master cylinder and now there is no fluid coming out to power the rear brakes. I bench bleed the master cylinder before putting it on the vehicle.
Wednesday, March 11th, 2020 AT 6:44 PM

5 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Okay. How are you bleeding them? Manual or pressure bleeding?

How long have you bleed them? Is the fluid in the master cylinder dropping at all when pumping them?

I attached the manual bleed procedure. Just review it and see if there is anything that you may be missing even though this is pretty straight forward. Thanks
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Tuesday, March 16th, 2021 AT 10:12 AM
Tiny
TRAVELINGMAN5352
  • MEMBER
  • 2 POSTS
My problem lies within the master cylinder itself as I've disconnected the front line from the master cylinder and there is no fluid coming out when your press the brake pedal.
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Tuesday, March 16th, 2021 AT 10:12 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,877 POSTS
It sounds like the master is defective or it is not bled correctly. here is a guide to help you recheck your work:

https://www.2carpros.com/articles/how-to-replace-a-brake-master-cylinder

Please run down this guide and report back.

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Tuesday, March 16th, 2021 AT 10:12 AM
Tiny
TRAVELINGMAN5352
  • MEMBER
  • 2 POSTS
Sorry for the late reply. The new master cylinder was bad. I replaced the master, Bench bled it and am know getting fluid to both the back brakes. My problem now is that it's like stepping on a brick, it does stop the vehicle but slowly.
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Tuesday, March 16th, 2021 AT 10:12 AM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
If you are lacking assistance, this sounds like the brake booster has failed. The booster is what provides the braking assistance so more than likely you have a leak in the diaphragm.

You can either rebuild it or it would be easier to replace it. Here is the procedure to do this:
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Tuesday, March 16th, 2021 AT 10:12 AM

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