Booster Pump running frequently.

[BeSerious]

Hi all.

I recently changed my accumulator bowl as well as the pressure switch in my
powermaster setup, and since then, I have noticed that the pump runs pretty frequently.
I never noticed it run more than once at start up prior to replacing the bowl and switch.

I've read through that diagnostic checklist, and didn't come across anything I thought
was relevant so I figured I'd ask here.

Any insight would be appreciated!
Have a great day,

Justin.

 

[BEATAV8]

A pump activation once every 2-4 pedal pumps is typical. Heavier pedal pumps use more fluid than lighter pedal pumps, so there's some variation.

If you fully charge the system and then key off, you should get 15-25 pedal pumps before the accumulator is empty and you feel the pedal go hard. Again, heavy application of the brake pedal uses up more fluid than a light one. When you key back on you should hear the pump run for an extended period (~15-20 seconds) as it recharges the accumulator.

If it behaves this way it's working properly. Since you have a new switch and new accumulator you should be in pretty good shape. However, I did once upon a time come across a brand new switch that just didn't work properly and had to replace it again.

The last thing you could go after is to replace the internal seals in the master cylinder. The best kit I've found is available from Karps power brake service. The Karps kit has all the booster seals as well as the actual brake cylinder seals (hard to find!). If the seals are worn, the booster section can leak down faster and also uses more fluid with each actuation.

The seal kit also includes a new check valve seal. Super important...

 

[BeSerious]

If it behaves this way it's working properly.

Awesome!
Thanks a lot BEATAV8!

Justin

 

[BEATAV8]

Awesome!
Thanks a lot BEATAV8!

Justin

Yep, no problem.

on a side note, if you know your gonna park the car for an extended period (more than a few days or a week), go ahead and "pump it down" with the key off to discharge the accumulator and relieve the pressure in the system. I think this is easier on the whole system and will help it last longer than compared to leaving it parked with the system fully pressurized for days or weeks at a time. Also once per year open the lid and suck out all the old brake fluid and refill with fresh fluid to keep the system clean.

 

[BeSerious]

The last thing you could go after is to replace the internal seals in the master cylinder. The best kit I've found is available from Karps power brake service. The Karps kit has all the booster seals as well as the actual brake cylinder seals (hard to find!). If the seals are worn, the booster section can leak down faster and also uses more fluid with each actuation.

The seal kit also includes a new check valve seal. Super important...

I might go ahead and do this, since after reading your post and going and testing it, the pump seems to run a lot more frequently than 15-25 brake applies..
I am kind of a novice but it doesn't take a rocket scientist to know that you don't want the pump working more often/harder than it should be, especially considering
the price of replacement.

I will also take your advice about discharging the pressure, as well as changing the brake fluid.

Thanks again.

Justin

 

[BEATAV8]

I might go ahead and do this, since after reading your post and going and testing it, the pump seems to run a lot more frequently than 15-25 brake applies..

15-25 is what you can expect with key off before the pedal goes hard. this represents a complete discharge of the accumulator volume without running the pump at all.

With the key on, 2-4 is about all you should expect between pump cycles. this represent only a small discharge of the accumulator volume, just enough to drop the pressure down to the pressure switch turn on point.

 

[BeSerious]

15-25 is what you can expect with key off before the pedal goes hard. this represents a complete discharge of the accumulator volume without running the pump at all.

With the key on, 2-4 is about all you should expect between pump cycles. this represent only a small discharge of the accumulator volume, just enough to drop the pressure down to the pressure switch turn on point.

Ahh. Now I feel better.
I'm still going to look into that kit,
and follow your other recommendations.

You've been a great help,
Thanks again and Merry Christmas.

Justin