weak pedal after bleeding (4X!)

1995 Del Sol VTEC.


I've hit a roadblock. I've bled the system 4X and flushed out the old
brake fluid with motomaster crap before flushing it again with genuine
honda fluid. Although it's my first time bleeding brakes, at this
point, I'm pretty sure there is no air in the system. I tightened the
banjo bolts extra well (had them off prior to paint calipers - realize
that put air in the system), and i made sure to tighten the bleed
nipple sufficiently during the bleeding process. At first we started
pumping the brakes about 10X then bleeding. I noticed a leak under the
engine at some point afterwards - looks like it might have been brake
master cylinder. Perhaps I created too much pressure in the hydraulic
brake pressure by pumping 10X? Anyway, I proceeded to pump only 2-4X
per bleeding cycle.

Now when I was all done, I had a firm feel to the pedal. As soon as I
started the car, the pedal sinks to the floor and is very weak and
offers no resistance. The way it is now, it's worse than it was before
in terms of pedal feel. (very soft, and pedal doesn't gradually rise
with subsequent pumps)

Any ideas?

 

=====================

It sounds like your helper pushed the brake pedal too close to the
floor. You're never supposed to push it any farther than it travelled in
it's lifetime, because there's grit / filings / corrosion in the lower
recesses of the master's piston, just waiting for the seal to travel too
far and get mutilated.

Replace the master with a rebuilt or new. Put wood 2x4 under pedal next
time. Also bleed with engine OFF and all vacuum released by pumping
pedal lightly a few times. Blead from front left, front right, rear
right, rear left. (assuming your car has the steering wheel on the left
side)

Sorry:-( 'Curly'

 

Mach5 wrote:

I Agree with Curly, you messed up the seals in the master cylinder.
Don't feel to bad about it, it is a common mistake. I did it too way
back when when I was young and dumb. I did have the sense to do it to my
brother's car, not my own, though.

 

with respect, i don't agree. i've replaced master cylinders on many
vehicles with really stupid configurations /way/ less sensible than a
honda, and sometimes, the /only/ way to get them to bleed /is/ to press
the pedal to the floor. even if you have a vacuum/pressure bleeder.
this is particularly true in a tandem cylinder where the second piston
only moves if the first is fully bled or the first sinks low enough for
the two to touch.

i know a lot of folks swear that you should never floor an old cylinder,
and there is an element of truth to that, but otoh, if a cylinder fails
after such an operation, it is just as likely that the cylinder was on
the way out anyway. in addition, there can also be a reaction between
new brake fluid and old seal rubbers as well, so failure is not always a
direct result of this mechanical action.

bottom line, proper bleeding is much more important than trying to
preserve a dodgy old cylinder. if the cylinder subsequently fails,
replace it and than don't worry about it for another decade. and
remember to change the fluid every year next time - it slows rubber
deterioration.

 

I'd say the master cylinder is probably gone. To see if this is the case,
take it out and look inside the booster for brake fluid. If there is brake
fluid in the booster, the master cylinder is definitely shot. Replace if
this is the case. When bleeding the brakes, to ensure proper air escape
from the lines, do in this order: Right-rear, Left-rear, Right-front,
Left-front. If you'll notice, the pattern is directly related to the
distance from the master cylinder. (The right-rear is the farthest,
left-front is closest) I know someone else said to do it another way, but I
can tell you from doing this a number of times, the order I just mentioned
works best. Also, everytime I've bled my brakes, I do it with the car
running. Again, others may disagree, and they may have valid points, but on
my 1990 Civic and my wife's 1986 Acura Legend, doing it with the car running
worked the best. (The car has power brakes, so therefore you must have
power to operate correctly) Generally, it takes two people to bleed the
system properly. One to pump-n-press, and one to bleed the lines. The way
I've always done it is to pump about 4-6 times, then press and hold. At
that time the person bleeding the lines should loosen the bolt to allow air
and fluid to escape. When the pedal hits the floor, holler and tell the
other person so he'll know to tighten the valve back up after all air
escapes. When all air is out of the line, he should tighten the valve and
tell you to let up on the pedal. Repeat until all 4 wheels are done.

Good luck!

Jonathan

P.S. After doing this, if you have a new master cylinder and you've bled
the system 2 or 3 times, and STILL don't have a firm pedal, check all brake
lines for leakage, and if you have rear drum brakes, you will have to take
the drum off to see if fluid is escaping INSIDE the drum. (I had this
happen on my 1990 Civic) If this is the case, take it to an experienced
mechanic or a dealership to repair.

P.P.S. If you replace the master cylinder make sure to follow the
instructions to bleed the master cylinder (yes, you have to bleed it as
well) BEFORE installing it. This is CRITICAL!

 

thanks for the help guys,

yes, doing in proper order. RR,FL,RL,FR....Sad part, is that I have a
chiltons and a helms and I wasted a whole day on this. Yep, using clear
tubing and always fully submerged in new brakefluid.

Hard to judge where it was leaking from since it turned into a small
puddle before I realized it. It looked as if the fluid leaked from the
bolt on the side of the MC? It's difficult hard to say. I think it was
the CV boot that's directly under the MC that got covered in fluid. In
any case, it hasn't leaked overnight or during my second round of
bleeding today. (3 pumps/bleed)

Yep, bled the brakes again today. Bought new clear vinyl tubing that
fits better. Bought more brake fluid, and here's the procedure I used.

Pump brake 3 times, hold pedal. 1/4 turn to open bleed bolt. wait and
watch fluid 10 sec. tighten bolt. repeat. We repeated this another 7
times / wheel. Watching the level in the MC carefully as not to drop
and suck in air. Not once did I see air bubbles during my bleeding
today, which leads me to believe there is no air in the system. I
refilled the MC once, so I esentially bled it's entire capacity.

I took it out on the road carefully today. The brakes ARE working. But
here are my symptoms. Without ignition, pedal feel is firm/strong and
rises with each subsequent pump very quickly. put once i turn on the
engine, it feels soft and doesn't rise with more pumps. it takes almost
the entire pedal travel before I get maximum braking. prior to the
flush, it took much less pedal travel to lock up the brakes. i did a
70km/h to zero stop today and the brakes only barely locked up toward
the end when ABS kicked in for 1/4 of a second. and that was pedal to
the floor.

I am not an expert on brakes, but i'll have to say I was also beginning
to think my MC might be shot. I guess I'll make a trip to the junkyard

 

This is normal. Every pump uses up some of the vacuum stored in the
booster, so each subsequent pump gets less assistance from the vacuum
booster.

Glad you weren't behind me!

Wouldn't you rather get a new one?

 

But with the ignition on, shouldn't the pedal behave the same way? ie:
rising with more pumps?

Hmmm...do you mean from the stealership? where would you suggest I
might find a new one, if not? apart from the dealership, i didn't think
i'd find a new MC anywhere.

thanks

 

A couple of sites I've used online are:

http://www.cheapesthondaparts.com/
http://www.hondaautomotiveparts.com/

I've used both of them before and they were great. It should definately
save you some $$$ vs. going to the dealership and they are oem parts.

-Dave

 

Mach5 wrote:

If the brakes are working properly, pumping the pedal with the engine
running should make no difference. If you have air trapped in the
system, it is common for the pedal to get firmer as you pump it with the
engine running.

http://www.hondaautomotiveparts.com sells new OEM master cylinders for
around $195. I know it is a good chunk of change, but it is a
once-in-a-decade type replacement. You can probably pick up a rebuilt
one for much less than that at your local auto parts store.

 

holy crap! I was estimating like $40 bucks for a MC, but wtf do I
know?? jeeez. hehe...that's awful, and makes me feel even dumber for
not blocking the brake pedal with a wooden chock. definately gonna get
a new one, as the braking system is not something i'd like to test with
a 'rebuilt' unit. i worked at a videogame store once where we sold
refurbished hardware. what a complete farce that was, haha. nothing was
tested prior to resale.

majestic is in the states, is it not? so that's $195 US? Yikes.