shroomster

ok...I'm sitting dead still in traffic or whathave you...no slope or anything...I have my foot on the brake and then after hiolding the pedal in for like 5-10 seconds...the pedal sinks a little farther down...like another 10-15 mm or so...and stays there...doesn't move any farther......what is that?

sorry if my explaination is a little bland but ask me to elaborate if I need to...

Boilermaker1

iTrader: (16)

less vacuum at idle.

shroomster

alright thanks boiler....I was hoping it was something logical

holdUdown

that happens to me too i always wondered what the hell it was

streetglower

iTrader: (13)

actually there is more vacuum at idle. less as the throttle plates open more. But what I think happens is when you are at stand still with the foot on the pedal and a load kicks in, the idle drops for a split second thus there is less air and more vacuum creating that slight drop in the pedal. I notice it all the time too and that is what I was thinking happened. I will ask a teacher monday though at school.

shroomster

hey if you're asking someone and getting free info ask them what it means if it does that drop during braking....step on the brake to slow down and the pedal does the same drop....It started happening around 50k doesn't do it all the time either...its weird Honda couldn't reproduce it so they couldn't diagnose it and my mechanic friends couldn't either...

gearbox

iTrader: (95)

if that starts getting worse, the master cylinder could be on its way out.

shroomster

I already replaced it at 51-53k thats what is irking me...is there a dye or something that can be placed into the line to check for leaks? thats my next guess on this but I haven't pursued it cuz It isn't a nagging problem...I'm also leaning towards a 'sticky' piston in the caliper maybe? doesn't push out immediately?

shroomster

thats just what I thought when it started happening...one of the gaskets/orings w/e inside was failing... but nope I replaced it and it still was there....I was wondering if there is a dye or something that can be plced in the line to check for leaks? doesn't a pinhole leak make a huge diff?

I was also leaning towards my theory of a 'stuck or sticky' piston in one of the calipers....doesn't come out immediately when applying the brakes...that would cause a minor jolt or the action i mentioned earlier while applying the brakes right?

shroomster

thats just what I thought when it started happening...one of the gaskets/orings w/e inside was failing... but nope I replaced it and it still was there....I was wondering if there is a dye or something that can be plced in the line to check for leaks? doesn't a pinhole leak make a huge diff?

I was also leaning towards my theory of a 'stuck or sticky' piston in one of the calipers....doesn't come out immediately when applying the brakes...that would cause a minor jolt or the action i mentioned earlier while applying the brakes right?

lxcivic2k1

its only a problem when it goes to the floor and the car starts goin...
An older Charger 500 did that to me while i was moving it at my work inside a building. It scared me to death, cause i was was trying to park it and i only have like 2 ft. max of room on either side.
If it does that its a bad master cylinder.

streetglower

iTrader: (13)

ok sorry what I meant to say earlier to your original question about the small drop at idle with the brakes applied, it happens when a load is disconnected, I said when a load kicks in. When say the AC compressor clutch disengages, the idle will drop back down since the IAC wont be allowing any extra air past the throttle plates, thus vacuum will increase and cause that small drop.

But to your next question, does it happen all the time or just some times or just when a load disengages? Now if it slowly creeps to the floor but will come back after pumping the pedal a few times, that is your master cylinder failing. The fluid in there is bypassing the primary piston seal. If it falls away when the brakes are held then you may have fluid seeping out somewhere. and you may have that. Do you notice the level of fluid in the resovoir falling?

Now I remember you saying your master cylinder was replaced awhile back and my next question is does it take alot more pedal effort to stop? I know awhile ago you were having the same problems and I thought it was a pushrod issue after having the master cylinder replaced. thats why I ask again if it takes excessive pedal effort or you have to push the pedal farther to stop?

shroomster

actually no...it doesn't take any extra effort...no fluid level drop(running mix now...wasn't until I had my rotors swapped at 56k...of DOT4 and DOT3)

pedal doesn't drop to the floor

I've never had to pump the brake pedal...


its just a movement like the pedal is going down about 15-20 mm itself then it's back to normal (in other words you're starting to brake, pushing down on the pedal...yiour foot stays on the pedal but it feels like the pressure has dropped out of the pedal and it goes down with your foots motion about 15 mm. then it's back to normal until you get to the needed pressure point to stop the car...) dunno if this clarifies at all....its weird like ya said...didja happen to know if there is anything to do to check for leaks in the vac hose?

streetglower

iTrader: (13)

I think its just the vacuum issue. I notice it sometimes too. Once the load disengages, the idle will drop back to normal and more vacuum will be there. if you feel though something is wrong, take it in.