So i've been noticing this problem for a while and its starting to bother me now. I notice it when i'm at a stop light with my foot on the brakes. I can hear this very faint thumping sound and if I wear shoes with a thin sole, I can feel the pedal very mildly following the beat. Once I let off the brake and let the car roll the sound goes away, as does the pedal movement. The brake fluid was changed about 2,000 miles ago (it was doing the problem before the brake job) but changing/topping off the fluid didn't seem to do anything for the problem. Any ideas? I'm guessing the master cylinder is on its way out

 

hmm.. that's peculiar.. front engine mount? I've never had that with a failing master cylinder.. is the pedal feel strong / weak?.. keep us updated

 

did you have your wipers on? If yes its common since the wipers attach to the fire-wall. If not, put the car into neutral and see if it still occurs. If yes, its probably air in the lines or the master cylinder.

 

I was going to ask if it was raining, but AJ always beats me to everything

 

This is exactly what I thought when I starting reading this thread... scrolled down and saw someone beat me to it. Nice! This is most likely what it is... some techs are lazy and don't bleed all the air out when they flush the brake fluid.

 

Wow, forgot all about this thread.

It can't be anything to do with the brakes because once I put the car in neutral, the sound goes away. Put it back in neutral, and it comes right back (when the car is at a stop)...so that cancels the brakes out.

Any ideas?

 

If you are getting a brake fluid flush- there should not be any air to remove from the line
Only if you open a brake line, like at the caliper, do you have air in the lines to deal with

Really lazy techs suck out the master and refill it- call it done
That does nothing for the customer- this fluid does not circulate- its only moves back and forth a small distance, and does transport moisture vapor thru the lines to the calipers, A real brake fluid flush gets new clean fluid coming out the bleeder at each caliper

 

Well I doubt its the brakes because the problem goes away completely when I put the car in nuetral...

 

as you sit with your foot on the brake- the vacuum assist to it loses boost.
That will make the pedal drop slightly and perhaps you feel more thru the pedal.
When in N the vac boost is higher from the slight rpm increase
How are your brakes- actually inspected??

Anyone ask the dealer about this yet?