How to flush the slave
procedure was performed on a normal aspirated two wheel drive 993, the
993 twin turbo and the 4 wheel drive model cars have a different hydraulic
circuit which is separate from the brake's hydraulic system, the procedures
to bleed the slave cylinder maybe different)
The 993's clutch system is operated on
a hydraulic system that require routine fluid change. What makes
this particular job difficult is that the clutch slave cylinder's bleeder
valve is located in front of the clutch slave cylinder on top of the transmission.
In order to keep your eyes on the fluid flow and operate the wrench there
is no way you can get to this part with both hands. Unless you perform
the process with another person's vision.
The procedure itself is simple, but this
is definitely an 1 hour job.
(1). Jack the car up from the left rear
jacking point, and place jack stand under the front jack point and rear
suspension pivot point. I did not rest the car on the jack stands,
they were there strictly for protection.
(2). Remove the left rear wheel.
(3). Remove the engine and transmission
(4). Reach up to the slave cylinder area
from under the car with your left hand while lying on the floor .
Pull off the protective rubber cap on the end of the bleeder valve, push
on a 1/4" clear vinyl tubing onto the end of the bleeder valve with the
other end in some sort of disposable bottle for catching all the old fluids.
(5). Hook up a power bleeder unit,
or some sort of pressure bleeder unit to the brake fluid reservoir. Prior
to hooking up the unit make sure you first remove the white cylinder inside
the brake fluid reservoir.
(6). Get back underneath the left
rear of the car, and use a 7 mm open end wrench to unbolt the bleeder screw,
since the limited maneuver area this will require at least two movement
of the wrench before the fluid will be compressed out.
(7). It is always a good practice
to change the to a different fluid color fluid when doing a hydraulic system
flush, this way you will know when all the old fluids is completely flushed
form the system when you notice the color change.
(8). Tighten the bleeder screw and install
the rubber cap and the rest of the stuff. Double check the brake
reservoir level after you have lowered the car.
Ray Calvo (pops) said that I am
a RAT for not mentioning in this web site that
I took this picture from the left rear
wheel well opening of the car, so here it is :)
case if you guys are interested in Ray Calvo's clutch slave bleeding experience
please read on.... "It is funny :)"
Killed three birds with one stone
Posted By: Ray Calvo <firstname.lastname@example.org>
Date: Saturday, 24 February 2001, at
Well, kinda. After work yesterday, I
a) bled the clutch slave cylinder
b) tested my Power Bleeder
c) got some info off the Vertex front rotors
CLUTCH BLEED: printed Robin's procedure
for a laugh (read on), then went ahead with it. Generally followed Robin's
directions, and agree accessing the bleed screw is a royal PITA. Definitely
a touchy-feely job, you can't see a thing if your hand is up there trying
to access the bleed screw. Tried both box and open end wrench; think I
opened the screw with a box and closed it with open-end. The screw is very
loose (well, mine was); I didn't even realize I had broken the screw loose
till I reached up and found I could move the screw with my fingers. The
screw is a lousy design - about 1" long, made up of about 1/4" of nipple
end, 1/4" of hex wrench fitting, and 1/2" of smaller pipe end. This setup
is just asking for trouble like being very difficult to position a wrench
on the hex fittng and possibly overtightening and snapping off the bleed
AND ROBIN, YOU RAT!!!!!!! Your pretty
picture on your web site? While working on the car, could not figure out
where you shot that picture. Finally noticed it was shot from the left
wheel well, looking in to the top of the tranny. ONLY YOU HAD TAKEN OUT
YOUR SPRING/SHOCK!!!!!!! Let people know, will you? Also, you had a jack
stand under the rear suspension mount? How you did this and still accessed
the bleed screw is beyond me; anyplace I put a stand got in my way when
tried to get to the screw.
POWER BLEEDER: Followed the directions
with the unit; will say it's nicely made and easily possible to get a airtight
seal. Have to pump like crazy to pressurize the unit, but works as intended.
I only filled it with about 1/2 liter of fluid; made it easy to tilt the
unit when wanted to stop filling the master cylinder and vacate the fill
tube and bring the reservoir level down to normal point. One thing I will
say: place the bleeder below the reservoir, and run the fluid supply line
so that the center is higher than the reservoir; makes it easier to vacate
the supply line and lower the reservoir level to the desired value at the
end of the job.
Was all this worth it? I don't know. I
pulled out about a pint of fluid; the first portion had the look of used
engine oil; black and totally opaque. Quickly took on tint of clean fluid.
Initial clutch trial and drive on crisp below freezing night seemed to
indicate clutch was like new. After about 1/2 hour, noticed some clutch
pedal hangup again. When pulled into the garage and worked the clutch with
the engine off, could definitely hear a loud squeak from the clutch, and
the pedal felt notchy when I was letting it up. So, might have more problems.
some comments from Jim Stover after his experience with the clutch slave
"James A. Stover" <email@example.com>
Subject:Brake fluid change
Sent:Mon, 14 May 2001 10:49:22 -0400
As I mentioned some time ago, I was planning
to replace the brake fluid in my 95 993 and would send you some comments
on the experience in case they might be of general interest. I did it last
weekend. Since my car has Option 224 (Active Brake Differential), I expected
it to have the hydraulic pressure unit. I do not see how ABD could work
without an independent pressure source. Nevertheless, I could not find
the pressure unit or the accumulator tank in the car. So I just went ahead
with the normal procedure. The Motive pressure unit is a neat device;
Ray's (?) idea of making a "T" todo both cylinders at once is the way to
The only procedure I did that might be
of general interest was the clutch cylinder bleeding. I'm not sure if it
contributes anything new over what you have already covered on your web
page, but below is a write up. Use it or not, any way you wish. It is actually
quite easy to do.
"Put the car up on jackstands to a height
that allows you to easily maneuver your body underneath the car. Remove
the left rear wheel. From below the brake disk, using a light, you can
see the clutch cylinder resting atop the transmission in all its inaccessible
glory. (See Robin's picture). Move around until you can find a hand position
that provides enough strength to pull the rubber cover off the bleed nipple.
Long, ape-like arms are an asset here. Maneuver a 7mm, 12-point box-end
wrench over the bleed bolt and on up against the cylinder, where it will
hang freely. Work your bleed tube over the nipple. Secure the bleed bottle
out of the way so you won't kick it over. Pressurize the hydraulic system
following the instructions for your unit. Maneuver yourself until you can
get enough leverage on the wrench to loosen the bleed bolt. The bleed tube
will prevent the wrench from falling off. Watch the fluid going through
the clear bleed tube until it clears up. It is likely to be dark and grungy
looking initially. (Maybe this stuff should be bled out at least once a
year). When the exiting fluid is clear, snug the bleed bolt back closed
and disconnect the system, covering the nipple with the rubber cap"
Thanks, Robin, for all the help and advice
you have provided.