Jeep Wrangler Brake question

[straightlinespeed]

Stumped a little with this problem. A coworker has a Jeep Wrangler. When he pushes on the brake pedal it goes to the floor. As soon as he pumps it a couple times he has good pressure and the pedal holds, and stays. He drives it to the next stop light or sign and it does the same thing.

He checked for leaks, and says there are none and he never has to add fluid to it. We are both stumped, Any thoughts?

 

[halifaxhops]

I had something simalar with air in the prop valve.

 

[Tech857]

Does it have rear drum brakes? Wheel cylinders will sometimes suck air in past the seals when the pedal is released.

 

[straightlinespeed]

I had something simalar with air in the prop valve.

So you just bled the brakes to fix it?

Does it have rear drum brakes? Wheel cylinders will sometimes suck air in past the seals when the pedal is released.

Yes it does.. I will mention this to him.

One thing that he did find was that the cover for the fluid has a rubber gasket, it was pretty much rotten so he was going to get a new cover.

 

[sireland67]

What year wrangler?
Does the emergency brake hold.
Are you loosing fluid.
My guess is pads/shoes are shot.
Second guess is master cylinder has took a crap.

 

[straightlinespeed]

What year wrangler?
Does the emergency brake hold.
Are you loosing fluid.
My guess is pads/shoes are shot.
Second guess is master cylinder has took a crap.

-04
-Not sure of the E-Brake, I can ask
-Not loosing fluid
-Thought about bad shoes\pads
-Thanks, gives me some things to check out..

 

[volaredon]

if the star wheel adjusters are that far 'out" (frozen up or self adjuster cable broke) it wont adjust and as they wear, you gotta push farther to push the plungers of the wheel cylinders out far enough to work, The M/C only pushes so much fluid per stroke. If out of adjustment you gotta use more fluid to activate the wheel cyls, hence the pumping.

another possibility M/C leaking internally between chambers, M/C may just be shot

 

[PA Dodger]

Same problem on my '04 Ram with disc brakes all around. The problem with mine is the drivers side front caliper isn't retracting but it's not the caliper pistons. It's the sleeves where the caliper mounting bolts go are sticking/seizing. The caliper and pads are staying against the rotor but the piston is retracting. The pedal goes to the floor once then it's fine until the next stop. I love doing brake jobs in the winter.

Just something else you might want to look into.

 

[BillGrissom]

A fairly new MC showed the same symptoms long ago. I pulled the piston out and found the piston seal had been cut by a sharp corner in the bore. The rebuilder's had re-bored it but didn't break the edges on the ports. Sometimes it sealed and gave a hard pedal and other times the pedal would sink.

 

[Inertia]

Adjust the rear brakes.....

 

[straightlinespeed]

Thank you for all the suggestions. I printed off this thread and he is going to dig into it this weekend. Much appreciated guys!

 

[sireland67]

I just thought of something, when my 03 wrangler had 60,000 miles on it with the original brakes, the petal was low and pulsating.
The front rotors were completely wore out, actually getting really thin, but the pads actually was only wore down to about 1/2.
I think the factory pads on them are too hard.
Replaced the rotors and pads and the brakes were back to normal.