Hi,

first of all, i apologize if i will cover an already known topic, i don't know what to search that could point me in the right direction...

the problem:
basically the car drives fine, then if i to brake and then stop (traffic light for example), once the car is completely immobile, if i keep the brake pedal pressed (or if i release it and press again later), i have some sort of pump noise (like an electric water pump noise) going on and off and at the same time the brake pedal response varies in stiffness. If i press hard on the pedal at this time it goes a bit like a cracking noise (air bubbles in the lines ?)

as far as i remember, i've always had the sort pump noise at the first stop of the journey (usually leaving the garage and waiting for the door to open). I always thought it was something like the ABS being primed and ready. But now it keeps doing it for a long time. But still usually after 15-20mins drive the brakes are back to normal.

i didn't noticed any loss in braking power. Though i have potterfield carbon brake pad, so i have to eat them up before they brake hard, and i dont do spirited drive anymore so they usually are cold, though it brakes the car correctly. Also i had the car inspected recently (in France, cars must be inspected every 2 years) and they didn't found any issue either.

I didn't had the time to check the braking fluid level. I also expect the braking line to be fine, they are breaded line that have been changed like 3or 4 years ago (i'd say less than 20 000km old). And the fact that it only happens when the car is idling and with the wheels stop makes me think that it's something weirder, I'd think a vacuum line or something maybe ?

 

If you're not losing any fluids I would recommend looking into the brake booster
GL

 

You can also use this as a time to upgrade to a better and more common setup, if that's your problem. Clokker has a thread discussing several options from 90's Hondas and Subarus for BB/MC combos that bolt into the FC. I personally use and am a fan of the Subaru Legacy 1-1/16" option.

 

Your car must have ABS and it sounds like the pump is going bad, nothing else in the system makes any noise.

 

I thought about MC and BB, but if they were faulty, i would have issues at all time, not only when the car is stopped ?

I'm also thinking about the abs pump making the noise, but again why would it do that only when "parked" ? could be the ABS itself that's going mad ?

in any case, changing the abs pump, is it a hard and expensive task ? or am i lucky this time ?

edit: just checked... of course it's expensive, what was i thinking... so i hope it's something else... like a speed sensor giving false information hence the ABS trying to "unlock" the wheel as it suppose the car is still moving...

 

Not sure how difficult but I'd guess a rebuilt ABS unit would be pretty expensive.

For under $20 (at least here in the states) you could buy some generic brake line and delete the ABS altogether.
Which is what I'd do.

 

mazdatrix has some pump to sell, but it's over 2000$... which is a bit... too much...

Those last months have been a bit too much agitated for me so i couldn't check but I'll try to find the time to check the fluid level and check for any leak at the BB or MC (i'll start by supposing the line are good).

if in the end the pump is faulty or even the ABS unit, i suppose i'd do your removal proposal (anyway, i own the car for 6 year, i think i've used the ABS once...)