Master cyl replaced and still have issue

[BadgerType]

hello ppl

it started 2 weeks ago when my high engagment point suddenly went all the way to the floor. i could still shift but it was alot harder and more cumbersome. i knew it was my clutch master cyl and i was gonna replace it when i got back. well, i never made it back. the car wouldnt disengage the clutch and i couldnt risk driving it back home 30mi due to multiple traffic lights.

so i did a clutch master cyl swap in a parking lot and i saw dark fluid coming from the plunger. got a new cyl from ADAP and swapped it on, went through a small bottle of fluid and the line was clear of all dark old fluid. but when i tried to shift it, it still behaved pre swap and then after a few pumps, it was a dead pedal, no resistance

so now im at a standstill since this very simple device is causing me issues


Cliff notes/Specs:

new 93 master cyl
line is clear of old fluid
slave cyl moves 1/4" at most after bleeding then nothing
no visible leaks seen


Questions:

i did not bench flow the master cyl prior to swapping it on due to i didnt doit it the first time i swapped it last year, what is it and how do i doit?

is there an o-ring between the line and the CMS?

any help would be appreciated

[deevergote]

If you don't bench-bleed the master cylinder, it takes a LOT of bleeding through the system to make it work. I've bled mine for over and hour and I still only have partial pressure...
Bench bleeding involves filling the whole cylinder with fluid before you install it... rather than pushing out air bubbles through the entire system. This should be done with both brake and clutch cylinders.

Also, are you SURE it was the master, and not the slave that crapped on you? I replaced both at the same time. Always a smart thing to do.

I'm not aware of an O ring... but my friend put my master cylinder on while I was doing the slave, so I don't recall if there was one.

[Night Wolf]

you got to bleed it till the air comes completely out. just cuz it came clear doesnt mean your done.

[BadgerType]

thts what im figuring, i still have an air pocket. when i first did the swap the bleeding of the lines were done by a diy bilge pump the sucked the fluid down to the slave, then a few pedal primes and it was set

so i will try a bigger bottle of brake fluid and see if i cant find a pump to pull or push the fluid back up

it just seems weird tht the symptoms are near the same

and deev, while looking at my clutch pedal bracket, i saw some dark fluid drips and a good little bit of fluid on the wrong side of the rubber boot. so i assumed it was a bad master cyl. but i am assuming

and i dont think its the slave cyl do to the fact tht i can manually push my shift fork abt an inch to disengage my clutch put the pedal pressure at max could only move it 1/4"

and with no visable leaks, i assume tht much

Thanks guys

[Night Wolf]

is the slave boot wet on the inside?

[BadgerType]

i cant confirm tht right now, i spilled some fluid on the front of the tranny while moving my cup. i did not see any fluid on the slave prior to that but i cant be sure. you think the internals of the slave cyl are bad/torn?

[deevergote]

It's possible. It's just best to replce both master and slave at the same time. The slave is cheap anyway.


And yeah, fluid on the inside of the car, and on the master boot... that's the master going bad for sure. Doesn't mean the slave isn't right behind, though.

[BadgerType]

i see your point, at the moment i am just trying to get the car 80% operational so i can drive it back to where i am at.

i am desperatly searching for a spare bilge i could use to pull fluid down but if not, would gravity bleeding work better to release the air bubble, if any, in the master cyl?

would it be better to let the resivoir dry up till its down to the master cyl and then slowly, emphasis slowly, add fluid to the resivoir to fill the air buuble out of the master cyl?

[deevergote]

Open the bleeder valve, pump. Close the bleeder valve. Pump. Repeat. A lot.

[bcjammerx]

your original problem sounds like a slave cyl not master.

bench bleed as deev recommended as that could be causing all your issues currently. IF that doesn't work replace/rebuild (CHEAPER) the slave as well.

[deevergote]

Well, the master sounds like it was definitely leaking... so regardless, that had to come out. Doesn't rule out the slave, though.

[BadgerType]

well, before i buy any new parts, i will try to see if there is any more air in the lines. then off to buy a new slave cyl, i read your rebuild thread and it seems easy, but im down here for work so i cant waste a whole day to repair a part when it would be more economical for me to buy one.

so, i guess the general consensus is tht i just need to keep pumping until i get pressure back, then pump some more.

after reading over 30 some odd pages of the same topic, i guess its needed to have one thread to answer this question once and for all

[deevergote]

Since you need to bleed still, I'd replace the slave now... rather than trying to bleed the system (and fail, if the slave is bad)... or bleeding it just to have it crap out and have to be bled again when the slave does fail.

[BadgerType]

point taken. prior to my rebleeding the clutch, i will wipe the engine down and really look out for leaks. if the slave cyl leaks, it should leak under the boot, then i will know its the slave and then i can ask my boss to drop me off at honda. im working on my bosses time tomorrow and i dont want to piss him of driving to several locations and still not knowing the real problem.

i just need to sit down and really look for leaks or other issues

thanks deev

[BadgerType]

update:

after about an hour of bleeding and buying a hand pump, i still had little pressure at the firewall. my plan is no to bleed the system dry then pull fluid from the resivoir to the bleed screw via my pump

any other suggestions would be appreciated