How to Bleed the Clutch Hydraulics

My
C5 recently was exhibiting hydraulic clutch problems. It was not
releasing all the way causing hard shifting and grinding gears! I checked
the fluid in the master cylinder and it was at the right level but it was
dirty! It was dark gray and pieces of something were floating in it.
After posting a question to the CorvetteForum, several other C5 owners
were exhibiting the same problems. Is the seal on the cap deteriorating?
Is heat causing this? Who knows? This problem seems to happen in C5’s
that are 4 years old or older and the symptoms start to appear when cold
weather comes around.
Well, after changing the fluid in the
reservoir several times using a turkey baster, I got the clutch to operate
sporadically good, but it was still having problems. After consulting the
Service Manual, I decided to bleed the clutch, which resulted in a 100%
improvement. Now, my C5 shifts like it is brand new!
Instructions
with detailed step by step pictures are at
http://97vette.com/howto/clutchbleed/index.html
First, clean all
the dirt and debris, if any, from the clutch master cylinder cap to ensure
that no foreign substances will enter the hydraulic system. Remove the
clutch master cylinder reservoir cap with diaphragm. Fill the reservoir
with clutch hydraulic fluid (DOT 3 brake fluid or GM P/N 12345347).
Raise and support the C5.
Remove the intermediate exhaust pipe.
To do this, you must first disconnect the O2 sensor cables. GM recommends
that you disconnect the batter before performing any electrical
connections/disconnections. I left the battery hooked up and I was fine.
The connectors are located above the exhaust pipes just to the rear of
where they connect to the exhaust manifolds. Remove the blue retaining
pin. And, disconnect the wiring harness. Then, remove the retaining
clips.
Now, remove the 3 nuts which hold the exhaust pipe flange
to the exhaust manifold. There are 3 nuts per exhaust pipe that need to
be removed with a 15mm socket. I suggest leaving one nut on each pipe,
loosely, so that you can disconnect the rest of the exhaust system first.
Once all the other bolts have been removed, and the rear of the exhaust
lays on the floor, you can easily undo the 2 loose nuts and lower the rest
of the exhaust. Then remove the exhaust bolts at the other end of the
exhaust pipes. There are 2 bolts per exhaust pipe that need to be removed
with a 15mm socket. Then, locate the forward exhaust hanger, just behind
the clutch bellhousing. There are 2 15mm bolts that need to be removed.
Next, remove the 2 rear exhaust hanger bolts. These require a 13mm
socket. Undo the 2 loose nuts from the front of the exhaust assembly and
lay the exhaust on the floor. Slide the exhaust assembly out from under
the C5 and put it out of the way.
Next, locate the 36 bolts that
hold the Driveline Tunnel Closeout Panel in place. This is just above the
exhaust assembly you just removed. These bolts require a 5/16” socket.
Remove all but the rearmost and forward most bolts. Then, remove the
rear, and support with a leg or a 2×4 while removing the front. This
panel is not heavy but it is awkward. Place the panel aside.
This
exposes the torque tube. Face the front of the vehicle and reach your
hand up around the driver’s side of the torque tube until you feel the
bleeder bolt. Put a 7/16” wrench on the bleeder bolt and have an
assistant depress and hold the clutch pedal. Loosen the bleeder and
retighten. Fluid will shoot inside the torque tube tunnel and run down
your arm, as well as inside the bellhousing. Tighten the bolt and have
your assistant release the clutch pedal. I found that after I bled the
system, my assistant had to pull the clutch pedal off the floor. But, it
operated fine after that. GM recommends doing this 7 to 10 times until
you have bled any air or bad fluid from the system. Every 3 to 4 bleeds,
add more fluid to the reservoir in order to prevent removing so much fluid
that you draw air into the system.
When you have completed the
bleeding procedure, wipe any and all excess fluid from underneath the C5.
This stuff is flammable and you don’t want to catch your C5 on fire.
Then, reverse these instructions to reinstall the Driveline Tunnel
Closeout Panel and the Exhaust Assembly. Then lower your C5 and test the
results.