Rep Power: 369

workin on sister's 98 Civic 4dr LX AT
the brake light was on (I didnt realize the brake fluid was low. it was little bit above min. line)

I took out front wheels to check out the pads cuz she mentioned squeak. they were getting close to the indicator so I replaced them (had some new axxis metal master laying around)

when I push the front right piston back in via a caliper piston compression tool (loan from pepboys) I forgot to took off the cap for the mastery cylinder..

I also pushed the brake a few times while I was trying to press the piston back in (had to push in and out) cuz the boot wasnt seating in properly.

after I finish the front right, I went to the front left.

by this time the piston was out extensively on the front left caliper.. it also looks like the dust boot has somehow came off? I tried to seat the boot back on.. and piston was actually dangling around (I was like wtf?) then as i try to push the piston back in/reseat the dust boot.. the dust boot came out from the caliper somehow, and brake fluid came pouring out via the piston area.

while cursing up a storm and getting fluid everywhere.. (and air into the system).. I reseat the dust boot somehow (or at least I think its back in) and got the piston back in the caliper.. while fluid comes out as I press piston back in..

now I gotta bench bleed the system.. to get the air out.. but I'm not even sure if the caliper is okay. fluid shouldnt come out like that, even if the dust boot falls off. nor should the piston felt loose like that. is the piston seal somehow compromised?

that might be why the fluid level is low.. its been leaking slowly, and when I take off the pad and gave more room for the piston to travel, its now pouring out by the dozing via some leak.

anyways I know this is super long and i apologize for it, but I just want to give as much detail as possible. I'm not sure what the problem is, I still havent got a chance to bleed the system yet since its all dark now. i'll be doing that tomorrow while looking at the caliper piston again.

any suggestions/help would be greatly appreciated. I dont want my sister to be stuck without a ride.

edit: oh i forgot to mention. of course the pedal feel is soft now (brake barely works).. and when engine is on and when I depress the brake, I hear hissing of air leak around master cylinder.. that wasnt there before I think. but its there now. I put the cap back on tightly, so I duno whats wrong.

 
Rep Power: 369

i thought about it more, and I think it could simply be because I didnt take off the reservoir cap..

so this did a few thing maybe:

1. piston is completely unseated cuz caliper was left dangling while i depress brake pedal.. (no pads for the piston to press again, so it pooped out) and probably ripped the piston seal (or that happened when I try to push piston back in) piston wasnt out completely (like fell off) but it was quite loose.

2. while i push piston back in.. the mastery cylinder cap is still on.. excessive pressure (although I would think brake system can handle more press than what I can dish out via the piston compression tool) broke some seal or compromised MC, hence hissing around from that area. or leak in some seal, or hose..

so I think, worse case scenario:

1. caliper rebuilt or buy a new/rebuilt caliper.. I dont really feel like rebuilting the caliper. even if the rebuild kit is only like $18 bux.. it'll be messy and I gotta grab an air compression tool.

2. mastery cylinder rebuilt or buy new/rebuilt MC. this isnt worth the rebuilt I think, so I might get a new one..

both I think I can exchange old part for core refund..

sigh. its been so long since I did a brake job that, I forgot a lot of important steps. end up costing more just from a simple swap job.

best case scenario? caliper is still good, I wont require new one.. the fluid just magically leaked out and not due to my negligence.

MC doesnt need to be replaced.. all i need to do is to bleed complete system and it'll magically fix everything!

sigh

 
Rep Power: 0

you have to scoop some of your brake fluid out of the resevior before you push in the piston o your caliper
make sure you keep an eye on the fluid because it will eat your paint away....(PS once your done make sure your top it off and put cap back on so no air gets in your lines....)

 
Rep Power: 369

ah the level isnt high enough to worry about overflow

anyways I checked the front left caliper.. and i might have lucked out.. it seems to work properly.. no leak too.. so *shrug*

i duno. imma try to have the brakes work at least, then ill replace caliper later in a few days.

 
Rep Power: 307

there is nothing wrong with the master cylinder. And it does not need to be bench bled either.

You need to either get a rebuilt/new caliper on that side or rebuild it yourself. You damaged the seal on the left caliper. Pushing on the brake with the pads off, you pushed it out. The caliper is not even damaged, just the seals.

After installing a new caliper or whatnot, then bleed the system with the following order, RR, LR, RF, LF. Then everything should be fine.

 
Rep Power: 369

yeah thats what i figure too, but there's hissing noise from around the MC/brake booster area...

and there's more hissing noise (gets louder) whenever brake pedal is depressed. (around the MC/brake booster area)

I'm going to have the caliper ordered, then ill replace it.. and if the MC/brake booster area is still hissing and pedal is still soft after bleeding the system.. I guess thats when Ill take it somewhere to get it inspected.

 
Rep Power: 454

I hate to tell you, but I think you need a new master cylinder. When you remove pads or shoes, you are never supposed to push the pedal. what happened is there is a pushrod at the top of the accelerator that is connected to you master cylinder. When you pushed the accelerator with no pads, the pushrod went passed its normal length of travel and probably damaged one of the seals in the master cylinder.

That is why when you looked at the other caliper, the piston was sticking all the way out. And now that you have that hissing noise coming from the master cylinder, it sounds like you need a new one. And along with that, you need to rebuild the calipers. You can either do that or buy new ones ( acutally they are rebuilt, but new for you ). And dont even bother with rebuilding a mster cylinder, it isnt worth it. Just buy a rebuilt one. Leave the rebuilding to a professional who does that everyday. Remember the master cylinder is the heart of your brake system, any *** ups could cause a accident.

Now I am not an expert with brake systems, but not a dummy either. I have been studying truck air brake systems in class the past 2 weeks and we did a section on hydraulic brakes because some trucks use hydraulic brakes and it is the same as auto brake systems.

That is what I think needs to be done. You might get other replies, but from what you just described, sounds like you need a new master cylinder and rebuilt calipers.

 
Rep Power: 454

you have to realize that pushing on the pedal with pads removed, the piston on the caliper has nothing to push against with does damage the seals, your correct, but also your pedal will be pushed in farther which means the pushrod will be pushed past its normal length of travel possibly damaging the seals in the master cylinder.

 
Rep Power: 307

I will ask my lead man tomorrow about damage to the master cylinder. As far as I know, you cannot depress the pedal far enough to overrun the master cylinder. It should hit the limit of its travel before this happens, especially when the engine is not running and you do not have assist from the vacuum (brake booster).

There are lots of things going on here, could have a vacuum line loose. Could have had a bad master cylinder or brake booster before work was even started.

Although brakes are fairly easy to work on, there is a big safety issue, and a certain amount of knowledge should be possessed.

 
Rep Power: 369

wait u mean the brake pedal right? not accelerator.

anyways, I think the MC/brake booster needs to be fixed too yeah. it could be something simple as a seal/hose leak.. or one of the entire thing needs to be replaced.

I forgot I didnt had pads in driver side when I pressed the brake pedal. I pressed it to seat the one on the right which I just finished...

the caliper I can swap myself. will get a remanufactured one from autozone and swap this core in.. its not too expensive, about 50 ish.

anything i should watch for when i change the caliper? I know I should seal the brake line so i dont get fluid everywhere.. but havent really thought about how to seal it yet. heh.

 
Rep Power: 454

Yes I meant brake padal, sorry.

But like rickinthescv said, from what I know, on older master cylinders it is a problem, but maybe not so much on the newer cars. But having someone look at it might be good.

As far as the caliper, when you remove the brake line, you dont need to seal it, brake fluid wont be pouring out, it will be dripping out. I watched a guy at my work rebuild his, and when he took off the line, it would barely drip out. Just make sure to bleed the brakes afterwards.

 
Rep Power: 0

yeah man, bad idea to push pedal while the brakes weren't all back together. the easiest way to get he pistons back in the calipers is to use a bigger "C" clamp and use one of the old brake pads as a surface to push on.basically you just squish them back in. and remember.....no pushing the pedal when brakes are off from now on. :P

 
Rep Power: 369

i got it back in already sheesh. lol.

I had a brake caliper piston compression tool.. that made it easier to push back in than a C-clamp

anyways i'll be taking it to get it check out to see where that hissing nose/vaccum leak is coming from.

 
Rep Power: 0

C clamp is easier. the caliper compression tool is too small...not enough leverage.

 
Rep Power: 369

*rollseye*

what leverage? it pushes/compress the piston in.. not like a clamp that squeeze it in.. two different thing.

you're saying a tool specifically designed for a single caliper piston wont work as well as a c-clamp?

for what happened, I'd need a VERY long c-clamp... cuz the piston was all the way out.

anyways for future reference if anyone searches this thread... master cylinder is fine.

I did more test.. and pinpoint it to the brake booster. checked vacum line/check valve and it was working fine...

during pedal testing the brake booster wasnt working fully proper. ie: when brake pedal is depressed and engine is turn on, the pedal does sink lightly, which means booster is functional.

BUT, on leak test.. when engine is off, and you pump/press the brake pedal... the brake pedal should gradually rise up and get firmer/harder.. that didnt happen. it kept being soft...

so yeah.

brake booster, for whatever reason, failed. I'm guessing something internal (pushrod of pedal to booster/mc?) broke, the brake fluids were all contaminated too.. (nice colors of blue and green!)

so yeah. that was replaced and hissing noise is gone.. ie: vaccum leak from where-ever.

brake works fine now.

also replaced rear shoes. cuz that's gone.

welp, finally fixed.

oh wait, still need to replace caliper. lol. I'll wait on that and observe it, but it probably needs to be replaced.