F0RMULA

I used the search feature in advance and couldn't find what I was looking for... heres my dilemma:

1992 6-Speed Coupe around 119k [Daily Driver]


I noticed a weakness to the clutch pedal a few weeks ago, checked the master cylinder and there was very little fluid. Obviously this was my issue, so I sucked up the gooey ancient black fluid and refilled with fresh DOT3.

Everything was good for about 5 days, but I caught it earlier this time.. the fluid was just below the add line [very dark].

Anyway, this has been the routine for the past 1.5 weeks or so. I know I need to do some work, but this is my first ZF6 [ always had 4+3's before] and I know one of you will know better than I do.

What would your best guess be? Slave or Master Cyl?

I remember hearing that the connecting hose between them commonly has issues too?

I know I should just replace both and call it a day, but moneys tight and I'd like to just fix the problem if possible.

Thx for you help in advance

bogor

My -90 did the same. Had to replace the master since the fluid ended up in the floor mat...

BADDUCK

Also check the slave for leaks. Don't drive it like that, you could be stranded real quick.

sailorsteve

If the slave is leaking, it is probably thru the pushrod seal. You have to remove it to be sure. The hose is less likely to fail, but while you are checking the slave you can see some of the hose to look for a leak. As posted, a master cyl leak usually is inside the firewall and more difficult to spot without getting into it, but there have been leaks from the reservoir on the master, which you can see from under the hood. When you change either cyl, do not buy a DOM-type cyl, as they have a high failure rate. Buy a cast cyl instead.

lt4obsesses

If your slave is leaking, it leaks into the bell housing. You can see the fluid dripping from the bottom of the bell housing. This is my experience.

I have not had a leak problem from the master yet (knock on wood) but my understanding is that it leaks down to floor may inside the car at the clutch pedal.

Replacing the slave is actually a pretty simple operation.

jmgtp

I replaced the slave cylinder about a year ago - like others have said it leaked into the bell housing and I lost my clutch pedal.

At the time I was of the opinion 'if it ain't broke, don't fix it' and one thing I regret is not changing out the master cylinder at the same time as I am once again having a slight clutch release issue and I believe the master cylinder is to blame.

I've been in the same shoes, money can be tight and you only want to fix what is broke. Can't blame you.

That said, my best guess is that the slave cylinder is the issue. If you unbolt it and have a look it might be obvious. Mine was soaked in brake fluid that had leaked. Wetness at the bottom of the bellhousing would be another clue.

sailorsteve

There is more help at www.zfdoc.com.

F0RMULA

thanks for the help and the link.

heres where im at:

I topped off the master cyl. this morning, did a thorough search and found everything to be bone dry on this side of the firewall.

I went inside and dropped the kick panel, totally dry, this side of the master cyl. looks in decent shape as well.


So at this point I'm thinking it had to be the slave....right?


So I jacked the car, got underneath and the slave and it surroundings are dry. I wiped off/cleaned the bellhousing when I first bought this car a few months ago, and its still lookin fresh.


The line connecting the two looked very good, maybe even newer. I guess it couldn't hurt to tighten both ends of that [even though I think it would be wet if they were leaking]


I noticed on this car, the clutch has about 1.5 inches of play before the push gets hard.. is this normal? or a worn out master cyl?

The fluid has to be going somewhere? Unless I had air in my line all along [clutch was replaced about a year ago, so its the possible the entire hydraulic system was as well]

GREGGPENN

It's probably the slave and it's probably seeping fluid into the INSIDE of the bell housing.

Replacing JUST the slave isn't the best option. Why? Because of it's age, the connecting hose and master are 100% guaranteed to contain disintigrated particles from the lining of the hose and master. IOW, there's abrasive material in the fluid.

By replacing just the slave, it's likely to fail much sooner (again). If finances simply force you to do only the slave, go ahead. Just be prepared to have higher failure rates until you replace all 3 components simultaneously.

I have heard this from Bill Boudreau in person and it's on his ZFDoc website.

FYI: Even with new fluid with a slave-only repair, the older slave AND ESPECIALLY hose lining will expel it's aging rubber particles right back into the fluid. It will become black and abrasive much quicker.

sailorsteve

Possibly there was air in the system, but if I understand correctly, you just noticed the problem. Maybe it is a combination of some air from the beginning and a leak in the slave that hasn't shown up externally on the bell yet. If it were mine, I would flush the crappy fluid thru until it runs clear, bleed the system and then pump the clutch pedal a few dozen times to be sure there is no air left. Take careful note of where the fluid level is and check it on a regular basis. If it is lower, as you said, the fluid went somewhere. You are well advised to monitor this, as a trans rebuild is several thousand dollars. The zfdoc website has a diagnostic procedure for determining which cyl. is at fault if any.

FYI: Even with new fluid with a slave-only repair, the older slave AND ESPECIALLY hose lining will expel it's aging rubber particles right back into the fluid. It will become black and abrasive much quicker.

This info from Bill Boudreau about two weeks ago by phone- He now says the hose lining is nylon and does not deteriorate as he used to think- the only reason to replace it would be damage.