Please help ABS brake booster pump & accumulator (1 Viewer)

[jg105]

Hi All,

First of all thankyou for welcoming me here, really wish i have found this site sooner.

So having alot of trouble with my 105 cruiser and the abs brake booster pump & accumulator.

About 12 weeks ago was driving and pump failed causing loss of brakes, so took it to my mechanic and we put a complete used abs pump master cylinder booster in,
this worked for about a month and abit then symtoms of failing started to show.
I then took it to a brake specialist who re-build pump motor for $2200 with a guarantee of no fail after that.
So i went ahead with the re-build with high hopes, anyway long storey short 10 weeks later still not fixed with a re-built motor, it is really doing my head in i have spent 3k so far and no better than when i first started.
Currently is has the usual abs light/handbrake on dash with the consistent beep, followed with the accumulator buzzing for 1 to 2 seconds ever 5 or so seconds it is then followed with a click nose coming from the fuse/relay box.
i will put up a video of the accumulator buzzing hopefully that helps.
Any help or advice would be greatly appreciated as i really im lost on what to do from here.

Thanks Jesse

 

[JunkCrzr89]

Air still in system or accumulator not holding pressure.

 

[MissouriLC]

Hi All,

First of all thankyou for welcoming me here, really wish i have found this site sooner.

So having alot of trouble with my 105 cruiser and the abs brake booster pump & accumulator.

About 12 weeks ago was driving and pump failed causing loss of brakes, so took it to my mechanic and we put a complete used abs pump master cylinder booster in,
this worked for about a month and abit then symtoms of failing started to show.
I then took it to a brake specialist who re-build pump motor for $2200 with a guarantee of no fail after that.
So i went ahead with the re-build with high hopes, anyway long storey short 10 weeks later still not fixed with a re-built motor, it is really doing my head in i have spent 3k so far and no better than when i first started.
Currently is has the usual abs light/handbrake on dash with the consistent beep, followed with the accumulator buzzing for 1 to 2 seconds ever 5 or so seconds it is then followed with a click nose coming from the fuse/relay box.
i will put up a video of the accumulator buzzing hopefully that helps.
Any help or advice would be greatly appreciated as i really im lost on what to do from here.

Thanks Jesse

Hi, Jesse:

The first thing to check is if the pump/accumulator is operating in spec. Do this:

• With the key OUT of the ignition, push the brake pedal 50 to 60 times. Push it as hard as you can. After 20 to 30 presses, you will notice the pedal gets very spongy. Somewhere between 50 and 60 presses, it should drop to the floor with no resistance. What you are doing here is pumping all accumulated, pressurized brake fluid out of the system accumulator, back into the reservoir.
• Get a stopwatch ready (your phone, etc.)
• Put the key in the ignition and switch to ON. Immediately start your stopwatch as soon as you hear the accumulator pump running.
• When the accumulator pump fully STOPS (it will stop and restart a few times as it is repressurizes the accumulator), stop your stopwatch.
• The repressurization of the accumulator should take LESS than 40 seconds total.

If the repressurization takes more than 40 seconds, you have a couple of potential problems. You could have residual air in the system, resulting from incomplete bleeding of the brakes. You could also have a failing pressure accumulator. Yours looks old, but I think that these fail pretty infrequently. You could also have a bad pressure sensor in the system.

Another thing to check; when the pump is running (almost constantly, it sounds like), are you seeing bubbles in the reservoir? You will notice this in the front of the reservoir, through the transparent plastic. If so, that would point to a bad pressure sensor. Basically, the pump will keep pumping against a fully pressurized accumulator, and excess fluid will be bypassed back into the reservoir.

Let us know what you find out!

 

[jg105]

Hi, Jesse:

The first thing to check is if the pump/accumulator is operating in spec. Do this:

• With the key OUT of the ignition, push the brake pedal 50 to 60 times. Push it as hard as you can. After 20 to 30 presses, you will notice the pedal gets very spongy. Somewhere between 50 and 60 presses, it should drop to the floor with no resistance. What you are doing here is pumping all accumulated, pressurized brake fluid out of the system accumulator, back into the reservoir.
• Get a stopwatch ready (your phone, etc.)
• Put the key in the ignition and switch to ON. Immediately start your stopwatch as soon as you hear the accumulator pump running.
• When the accumulator pump fully STOPS (it will stop and restart a few times as it is repressurizes the accumulator), stop your stopwatch.
• The repressurization of the accumulator should take LESS than 40 seconds total.

If the repressurization takes more than 40 seconds, you have a couple of potential problems. You could have residual air in the system, resulting from incomplete bleeding of the brakes. You could also have a failing pressure accumulator. Yours looks old, but I think that these fail pretty infrequently. You could also have a bad pressure sensor in the system.

Another thing to check; when the pump is running (almost constantly, it sounds like), are you seeing bubbles in the reservoir? You will notice this in the front of the reservoir, through the transparent plastic. If so, that would point to a bad pressure sensor. Basically, the pump will keep pumping against a fully pressurized accumulator, and excess fluid will be bypassed back into the reservoir.

Let us know what you find out!

Hi Mate,
Thankyou for your reply much appreciated.
I have tried pumping brake pedal without key unit it goes flat, the accumulator buzzes for about 20 seconds, then stops but then continues its cycle of buzzing for 1-2 seconds every 6-8 seconds. There are no signs of bubbles in clear tank, just the buzzing accumulator cycle followed by a click in relay/fuse box.
Would it be wise to bleed the brakes again?
Cheers Jesse

 

[MissouriLC]

Hi Mate,
Thankyou for your reply much appreciated.
I have tried pumping brake pedal without key unit it goes flat, the accumulator buzzes for about 20 seconds, then stops but then continues its cycle of buzzing for 1-2 seconds every 6-8 seconds. There are no signs of bubbles in clear tank, just the buzzing accumulator cycle followed by a click in relay/fuse box.
Would it be wise to bleed the brakes again?
Cheers Jesse

The lack of bubbles would suggest that the pressure sensor is okay. Therefore, you are probably looking at either a failed pressure accumulator, or air in the system.

Yes, I would bleed the brakes first. See my accumulator thread in signature for some tips and experience on brake bleeding (most from Paul, the excellent @2001LC ) I found that bleeding the brakes with this system is a complete pain in the ass, and it took me a long time to get it right. The rears are very easy to bleed. The fronts, not so much!

Good luck!