DSF

'88 CRX DX:
While the engine is off the pedal is nice and firm. The pedal gets harder and higher with each press. The pedal doesn't sink when pressed hard. Now while the engine is on, the pedal drops to the floor. It's not that it slowly sinks when pressed, it just takes pressing all the way to the floor to get any pressure. While the engine is running there is very little resistance in the pedal. Things I have done/replaced...

- replaced m/c with used one (was working fine on my other car before I removed it to upgrade).
- replaced driver front caliper with reman. unit. (was leaking)
- replaced both rear wheel cylinders with new units.
- replaced front lines with braided stainless (leftovers from my other car)
- replaced all pads and shoes.
- bled the system 3 times with a vacuum bleeder.
- bled the system once with traditional two person bleeding.

There are no visible leaks and no loss of fluid. The fluid is new and has zero water contamination. What would cause the pedal to sink only when the engine is running?? My only thought is the booster, but how?

Any thoughts...??

altoid

your booster or you check valve could be fizzucked...check em out.

try this: Depress the brake pedal with the engine running, then stop the engine. If the height doesn't vary while depress for 30 seconds booster is ok...if it rises booster is faulty.


[Modified by altoid, 12:23 PM 1/8/2003]

DSF

I tried that, but the booster checks out ok. I'll check the check valve tonight. It's weird, all symptoms point to a m/c or air in the system problem, but I've all but rulled those out. Maybe I'm a yet another victim Murphy's Law.

88_SC_CRX_Si

Might be time to get the system flushed, that would make sure there is no trapped air...

DSF

I did that on monday night. I bled/flushed about 1.5qts. of brake fluid in all. The pedal is nice and hard with the engine off and goes squish to the floor with the engine on

FourthGenHatch

Is it possible for the Prop Valve to go bad? When I did my rear disc swap and still had the Civic Prop Valve I had to press it to the floor to get it to work, but after I put in the Integra prop valve it was fine again. Can they go bad?

DSF

I suppose it could. At this point, there are very little things left to rule out. Unless I start double replacing parts

I Gotta Question

Do you have that hose connected from your intake to the booster? Did this happen all of a sudden?If not what did you do to your car?

DSF

[long story] Yep, the hose to the booster is connected. It's hard to say when these symptoms started happening. I had originally replaced the entire rear drum/trailing arm assembly with those leftover from my 92 Civic HB because the stock trailing arms had severely destroyed rubber bushings (i.e. they were completely gone). I figured it would be easier to replace the whole arm instead of having the bushing pressed out and replaced. At the same time I installed a new set of stainless lines on the front. (They were also leftover from my Civic.) Everything was fine for a while. Then my left front caliper started leaking, so I replaced that with, you guessed it, a leftover from my Civic. This is when most of the symptoms really started. I thought that I hadn't bled the lines enough so, I bled them about 3 more times to no avail. This is when I started replacing anything that could possibly be bad. I started with the m/c, then the rear wheel cylinders, then the right brake caliper... All to little avail. The car doesn't pull at all. It just take most of the pedal movement to build any pressure (while the engine is running). [/long story]

frusterating

E-AT_me

check your brake pads. make sure they aren't twisted/crooked.

SteveeeO

ill let u know the answer in about 4-5 hours ... got a mechanic diagnosing it right now, then gotta run to work.. (mine has the same problem)

also, the only reason the pedal is firm whenever your car is off because your vacuum boost is off, then when you turn ur car on it's on and makes it much easier to press to the floor

you sound like the exact same problem as me, put on your parking brake and pump the brakes (with your car on) it should work, it could be you MAY need to adjust your rear brakes - if this is the problem

but I will let you know the exact thing the mechanic says later on


[Modified by SteveeeO, 1:38 PM 1/13/2003]

Timmah!!

Did you put JUST the left front caliper on, I dont know if they are but They might be different, Just a thought, you might have different ammouts of pressure going into one brake cylinder... Does the car pull to the left side while breaking??

SteveeeO

I am guessing he just doesnt brake good, not the fact that it pulls hard to one side... it sounds soooooooo similar to mine, but opposite sides for me (my right side caliper piston seal popped, and my wheel cylinder in my right side drum was leaking) bled them all tons of times, still nothing, feels like air is STILL in the lines, there is no way it's the MC - because if the parking brake is on and it brakes fine, the MC is still pumpin... no way it's the pads because they were all replaced, no other visual leaks...

omahaturbocivic

My friends car is having the exact same problem too and we have replaced the master cylinder, brake booster, and the pads, and put about two quarts of fluid the all the lines trying to bleed them the conventional two man way. They are little better but still feel like there is air in the system. Let us know what your mechanic finds out!!!

Urban Business

i have the same problem. doesnt pull to either side tho. i figured it was just rotten **** for breaks i was using... however they're brand new =P

SteveeeO

master cyl, just did it myself... works fine, did u bench bleed the mc? it is faster and u can be 100% sure that all the air is out

just what I was told to do, its not hard to do

he checked every possible problem, even adjusted rear brakes and all.. it all leads the the master cyl

sporkcrx

I think that all rexes seem weak braking compared to most other cars. Whenever someone drives my car they think the brakes are going out...but as long as I can lock em up I'm fine.

moridin2004

I don't mean to assume any of you did something wrong, but I just wanted to ask how you bled the brakes. When you closed the bleeder valve, did you have the pedal fully depressed so no air would be sucked back in. I have the same mushy pedal problem, as did a few people on another forum (I haven't bled mine yet) and it turned out they weren't bleeding their brakes correctly. Sorry, I don't mean to assume, just wanted to check. Anywho, hope it works out.

Urban Business

bizump

thecorey

did you try adjusting the output shaft on the brake booster? try adjusting it out a bit...

oh yeh..**** that crx's have bad brakes bullshit...mine work great...especially since i replaced the m/c and brake booster...but even before that they worked great...its an 88 crx si


[Modified by thekori, 6:03 AM 1/14/2003]

DSF

Yeah, I'm thinking that it might be the m/c afterall. All of my pads/shoes are wearing fine and even. Rear shoes were adjusted, pushrod was adjusted, m/c was bench bled, car was bled using Honda's recommended sequence, was bled using farthest from m/c to closest sequence, was vacuum, bled, was single person check valve bled, was two person pump and open bled....yada, yada, yada. I think it may either be a piston that's catching in the bore of the m/c or I'm losing pressure between the between the m/c's pistons. Chances are that either occured when I initially bench bled the unit. Since it was used, it may have had build up farther down in it's bore and when I fully stroked the pushrod it either gouged the cylinder/piston or is binding up the piston. I'll see this weekend. I'm going to install a new/remaned m/c.

Luckily I got this pile of a car for free or I'd be really ticked

moridin2004

Dude, I got mine free too. Anywho, I hope it works out for you with the new MC. I need to go get one for the brake upgrade (Fastbrake's kit. Hopefully it was sent out today.) Anywho, good luck with the MC and I'm sorry for asking such an idiotic question. In my experience, it has always been something really simple that has been the cause of the problem. Guess not this time. Good luck.

DSF

Hehe, that's the whole reason I post here. So people can remind me of all the simple things that I forget about

Free cars are the best, except when they frusterate the hell out of you.

SteveeeO

dsf, howd it go? was the master cyl the problem for you too?

DSF

I'll find out tonight or tomorrow morning. I've been to lazy after work this week to work on my car