Brakes dragging on all four wheels

roverhi

1 1/4" body lift, 265x70x17 tires.
Supporting Member
Joined
May 16, 2021
Messages
290
Location
Oceanside, CA
All four brakes began to drag on the highway after I stopped for a light midway through a 20 mile trip. Had to add a bunch of throttle to get it moving each time I had to come to a stop. The brakes mostly backed off after driving a short distance but were still dragging. No steering pull either driving or braking. Pedal was very hard with little travel. Repeated at every stop till I got to destination. All four wheels very hot and brakes stunk. Don't know if tapping the master cylinder with a mallet helped but brakes backed off after sitting for a couple hours when I got to destination. Drove 20 miles home and brakes worked fine. Pedal seemed to have more travel than usual and a little spongy but car stopped without drama and dragging didn't return. The brakes had dragged before when the jeep sat for a couple months, happened twice. Forcefully pumping the pedal stopped the dragging and it didn't return till the Jeep sat again. Car has just been shipped to CA from HI , but brakes worked fine when it rolled off boat and about 50 miles of driving.

Do I have a bad master cylinder or is there some valve that would effect all four brakes that could cause the problem?? Doubt that it is bad flex lines as it affects all wheels evenly. Will flush the brake fluid as its probably 17 years old but any other ideas where I should start to find the problem.
 
IMHO prolly a bad master cylinder, or possibly the proportioning valve. I'd prolly replace both, do a proper brake bleed (and eyeball what comes out of the bleed in the way of rust/trash), then *I* would do an autopsy on the master cylinder just 'cause "I gots to know..."
 
As previously recommended.... do a thorough flush of the system would certainly be recommended.
Take a sample of the fluid in the master cylinder, a sample of what is flushed and a sample of the fluid after the flush.
Depending upon what the samples look like would depend upon what your next course of action would be.
Replacement of other brake system part could be required.
 
Is the proportioning part of the master cylinder. Somewhere remember reading a tool is necessary to hold the valve in position when working on the brakes.