If by cycling, your hearing the "screaming banjo" and see bubbles coming up front of reservoir at same time. With brake pedal not being depressed, and the frequency is increase with time. You'll need a new brake master.An update to my post #476:
At this point I've rebuilt the master cylinder, replaced the accumulator o-ring, spring and pipe, cleaned out the motor, and replaced the unit on the vehicle. I bled the system pretty thoroughly using techstream and pedal, and then actuated the VSC solenoids (SRMF & SRMR). Can someone confirm this is correct? I have a very firm pedal.
I'm still getting the same cycling from the pump/motor/accumulator.
Before I order a new pump/motor/accumulator, does anyone have any thoughts on other solutions/troubleshooting steps? Since I'm not getting a soft pedal, I'm wary that the issue is not mechanical but electrical, and that replacing the pump/motor/accumulator won't address whatever it is that's signaling the motor to keep turning on and off. I might be better off replacing the entire assembly but that's way more money.
Would I get a soft pedal if the accumulator wasn't holding pressure? Do the accumulators go bad?
BTW: Looking at your picture of motor front bearing and commutator. They look wet. If it came apart wet, and wet not from silage or you wetting. It's a sign the air vent is clogged. Clogged vent leads to vacuum of spinning motor sucking fluid from pump. This will damage the motor. Motor vent and pump drip ort need to be keep clean.
Make sure to check your battery voltage. A good booster motor time test, is take at ~12.4V or better. Lower voltage, motor turns slower and motor run time goes higher.Hey man, I did this check the bolts in the rubber cover and it looks good, but I did that pump timing test twice, I got 50seconds and 52 seconds. what I did is I hit the brake pad 40+ then turn the key on (not start engine), then it starts the pump, no warning sound, the car sit there overnight before I do the test.
So is it bad? or I did the test in the wrong way? If it is bad, will a dealer brake flush help?
Check voltage on battery post, and than on positive battery clamp and a ground point. Volts should be the same from all points.
Over 40 seconds, and you have and issue that needs correcting. Most common: air in system or weep/leak in system. It can also speak to heath of booster assembly i.e motor, pump and/or accumulator.