Break pedel goes to floor after changing RR Caliper

JOHN CURTIS

MEMBER
1997 CHEVROLET BLAZER
4.2L
V6
4WD
AUTOMATIC
170,000 MILES

I replaced the pads on all four wheels then also replaced the right rear caliper and bled it using a plastic hose to watch for air. I bled it long enough so I see new fluid at the right rear but the pedal still goes to the floor. Any ideas on what the problem might be?

8 Replies

CARADIODOC

MECHANIC
33,752 POSTS

The most likely cause is the master cylinder was damaged when the brake pedal was pushed all the way to the floor. Crud and corrosion build up in the lower halves of the bores where the pistons do not normally travel. When the pedal is pushed over half way, whether pedal-bleeding with a helper, being surprised by a sudden leak, or when pumping the pistons out of the calipers to adjust them, the rubber lip seals are run over that crud and they can be ripped.

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

Also consider that if the vehicle has anti-lock brakes, and the master cylinder was allowed to run empty while the caliper was off, it may be necessary to use a scanner to bleed the chambers in the hydraulic controller. The scanner will let you command the computer to open some of the valves so the air can be expelled.

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Friday, March 19th, 2021 AT 11:58 AM

JOHN CURTIS

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5 POSTS

Thank you CARADIODOC,
After my post I thought of the same problem with the master cyl and replaced it. I still have the same problem thou. With the engine NOT running I have a nice solid pedal but with the engine not running the breaks work but with a very soft pedal and will go to the floor.

My scanner doesn't have an option to reset the controller so I'm trying to find someone that does.
Thanks again,
John

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Friday, March 19th, 2021 AT 11:58 AM

JOHN CURTIS

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5 POSTS

Error in my last post.
I wrote.
"but with the engine not running the breaks work but with a very soft pedal and will go to the floor".
Should have been. "But with the engine running the breaks work but with a very soft pedal and will go to the floor. "

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Friday, March 19th, 2021 AT 11:58 AM

CARADIODOC

MECHANIC
33,752 POSTS

I take that to mean you do have anti-lock brakes. If you have the hydraulic controller that bolts to the master cylinder, as I recall, that doesn't require special bleeding procedures. It's the remote-mounted controllers that have chambers that can hold air and need to be bled with a scanner.

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Friday, March 19th, 2021 AT 11:58 AM

JOHN CURTIS

MEMBER
5 POSTS

Thanks again CARADIODOC,
Yes It does have anti lock breaks. The controller sits on top of the left fender well. I tried to bleed it manually as well but no help. That's where I'm afraid the problem is and I can't afford to bring it to the dealer.

I'm trying now to find some one with a scanner to bleed the anti lock controller. So far everyone I've talked to only has a scanner like mine. It only reads the codes.