Spongy brakes

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Jul 11, 2021 | 02:36 PM

Alkasetser

Thread Starter

Newbie

Joined: Sep 2017

Posts: 1

Likes: 0

From: Venice fl

Year: 1999

Model: Cherokee (XJ)

Engine: 4.0

Spongy brakes

I have a 1999 Cherokee sport 2wd. The brakes are super spongy when vehicle is running. I bled the brakes and the pedal is rock hard until the vehicle is started. There is fresh brake fluid, the pads have about half life left, they have been bled. Is it the master cylinder or brake booster? Thank you guys in advance for your help

Jul 11, 2021 | 10:28 PM

lawsoncl

CF Veteran

Joined: Dec 2017

Posts: 4,367

Likes: 1,215

Year: 1989

Model: Comanche (MJ)

Engine: 4.0

You still have air in the lines. Are they just spongy or is the pedal sinking too?

Jul 12, 2021 | 04:00 AM

country2

Senior Member

Joined: Nov 2016

Posts: 807

Likes: 124

From: Homer Georgia

Year: 2000

Model: Cherokee

Engine: 4.0l

Quote:

Originally Posted by lawsoncl

You still have air in the lines. Are they just spongy or is the pedal sinking too?

Booster, since he says good when not running?

Jul 12, 2021 | 02:45 PM

agreen

Senior Member

Joined: Dec 2020

Posts: 923

Likes: 250

From: North Augusta, SC

Year: 1998

Model: Cherokee (XJ)

Engine: 4L

No. The brakes will still be firm with the booster if there's no air in the lines. You still have air. Pull the drums, check the wheel cylinders for leaks, and reverse bleed with a mityvac.

(Pull the dust boots back a little on the wheel cylinders to check for fluid.)