Brakes not holding while rotating tires

So I rotated my tires on Sunday. After I got one side off the ground (and properly supported & parking brake on), I had my wife hop in the cab and hold the brakes so they wouldn't spin while getting the lug nuts off.

After a few minutes of holding the brake pedal down, the brake pedal wouldn't hold the wheel in place anymore. It was possible that the pedal was to the floor, but my wire doesn't remember). This happened on the two front wheels (after I switched sides) since I had the parking brake set on the rear.

It makes a squish sound when I depress the brake pedal - possibly coming from near the pedal or the master cylinder, which I recall hearing on just about every other car I've owned. For this reason, I didn't explore the sound further.

The brakes seem to be working just fine when the engine is running.

Is this all normal behavior? Specifically, the brakes not holding while turning lug nuts, with engine off?

Thanks guys!

 

Takes a lot more pedal pressure with the engine off and no power assist, the reserve vacuum ran out.

Your wife is weak.

I thought everyone knew to loosen the lugs before jacking up.

 

Yes. I'm assuming you are talking about your front tires. Mine move freely in the air as well even when brake is applied with e break. You just have to hold the tire while you remove the lugs.

 

x2

 

yep. loosen lugs a hair then jack up truck.

your brakes are vacuum assisted. the big round black thing on the firewall behind the master cylinder. it houses a diaphragm that helps to "pull" the rod into the master when you apply the brakes. vacuum comes from your intake manifold. a good vehicle will have residual vacuum pressure after the vehicle is off. but its only good for one or two pumps, if that. then, you have to rely 100% on your own mite to push fluid with that tiny little master piston to push all those caliper pistons.

remember in old cartoons when somebody would have to "stand" on the brakes for an emergency stop? that is what your wife would have needed to do to stop the wheels with no vacuum assist

 

LOL and

x3

 

Thanks guys.

Yeah I forgot to loosen the lugs before jacking it up - both times. It was 100+ deg outside, and since I didn't have a tall enough hydraulic jack for the truck I resorted to the one that comes with the truck. I didn't feel like cranking on the jack any more than I had to.

I'll be sure to tell my wife she's weak.

 

The "emergency Brake" only works on the rear wheels.


It's Brake not break.