no brake pressure with engine running?
10-24-2007, 12:14 PM
#1
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no brake pressure with engine running?
1977 f-150 6 cyl auto
my pedal responds with good pressure and normal return when the motor is off, but I lose ALOT of pressure ie I have to depress the pedal almost to the floor before the brakes engage and I feel any resistance and theres very little pressure to return the brake to its original position. the MCs resevoir is full, and the lines all look good....whats going on?
oh erm hi all
new guy here
my pedal responds with good pressure and normal return when the motor is off, but I lose ALOT of pressure ie I have to depress the pedal almost to the floor before the brakes engage and I feel any resistance and theres very little pressure to return the brake to its original position. the MCs resevoir is full, and the lines all look good....whats going on?
oh erm hi all
new guy here
10-24-2007, 12:24 PM
#2
Resident A-hole
Check for leaks in the system. Sit with the engine off with a decent amount of pressure on the pedal see if the pedal drops. Then do the same thing with the engine running. If the pedal drops slowly then the master cylinder is bypassing internally. If there are no leaks then try adjusting the rear brakes up some.
10-24-2007, 04:04 PM
#3
Senior Member
x2 on NGM's comments.
Also, another possibility to consider is air in the lines.
Do you have power brakes? Was the emergency brake engaged when you did either of the tests?
*Edit* - and finally- welcome to the site! I like to see older trucks on here.
Also, another possibility to consider is air in the lines.
Do you have power brakes? Was the emergency brake engaged when you did either of the tests?
*Edit* - and finally- welcome to the site! I like to see older trucks on here.
Last edited by wde3477; 10-24-2007 at 04:07 PM. Reason: added welcome!