Hi everyone, recently I was changing out the leaf springs on my 1996 Jeep Cherokee and I managed to hit the rear brake lines with something and it broke. Not a big deal, I ordered new rear lines (both drivers and passenger) and installed them yesterday. I filled up the reservoir and nothing was leaking so I started bleeding the brakes VIA vacuum bleeder. The vacuum Method didn’t work great so me and my dad did it the old fashion method. We got some old fluid out and got a bunch of air out too. Pressing on the pedal with the vehicle off the pedal is very stiff and doesn’t lose pressure, but once you start it the pedal goes almost to the floor with very little pressure. We did all corners and it’s still no better. My dad thinks the master cylinder went bad, but it was working properly a month ago when I parked it to work on the springs. I think it’s the proportioning valve underneath the master cylinder. I’ve done some research and apparently air likes to get stuck in there causing a squishy pedal. My dad has never seen air get caught in there so he finds it hard to believe. Any tips would be greatly appreciated as I want to start driving it again. Thanks!

 

Try bleeding the master cylinder. You can do it while it's on the vehicle. Bleed it last of course.

 

Ive always bleed brakes with the bottle and hose method. No bubbles, no air. It never fails. It’s difficult to get a good pedal using the old pump it up and crack the bleeder method especially if the lines drained completely.

 

I would agree that you have air caught somewhere. If you didn't have this bad pedal feel when you parked only a month ago, then the master cylinder is unlikely to have gone bad just from sitting for that short of time.

 

Do you have ABS?

 

If you ran the reservoir empty, you sucked air into the master cyl. While you're bleeding keep checking the level to make sure you don't run it dry and have to start over.

Bleed in order. Passenger rear, driver rear, passenger front, driver front. You won't get a solid pedal until all the air is out.

Inspect your brake hoses too. Sometimes they can balloon a bit and make to pedal feel soft.

And as Ralph77 asks, do you have ABS?

 

it doesn’t work, but yes

 

I do, I’ll take a look at the hoses. Thanks

 

Well isn't there something weird about how you bleed ABS brakes?

 

"Bleed in order. Passenger rear, driver rear, passenger front, driver front".

Then bleed the master cylinder.

 

I have ABS on mine. There is a device that gets hooked up to the Jeep through the OBD II port and it cycles the ABS cylinders.

I have never had this done (I'm not saying that it is not needed, just that I have never done it). I have bled my brakes through using a vacuum, and/or having a buddy pump the brakes the old fashioned way. On occasion just to satisfy my inner demons I have deliberately applied the brakes hard enough to activate the cylinders just to make sure everything works. 140K miles, and so far so good.

I would circle back to the OP's comment of "it doesn't work but yes" and look into if that is causing some or all of his brake related issue. I'm not a fan of having ABS hooked up that "doesn't work". Either bypass it, or fix it.