Hydraulic Clutch Fluid Replacement
 

Just had my 07 coupe in for oil & filter change at the local dealer. They wanted to sign me up for flushing the hydraulic clutch fluid, claiming it was part of the maintenance schedule under "Additional Required Services". Said it was about $300 because they had to drop the exhaust to do it. I did not go for it, but the service mgr showed it to me on his computer and he had it listed as required every two years. However, this maintenance is not shown in my hard copy of the owners manual, and it is not shown in the .pdf version of the owners manual posted online.

This sounds like one of those "additional" maintenance items they try to sell to increase service revenue. Anybody else encounter this?

It is not a bad idea at all to change out your clutch fluid. There are choices in how you do this and the easiest is a method shown to the forum by member Ranger who is arguably the foremost authority on clutch maintenance. Here is a link to a pdf I created based on Ranger's method of chaging out the clutch fluid. You can do it yourself in less than 30 minutes and with ease.

http://www.theredlion.us/C6%20clutch%20fluid%20DIY.pdf

Yes, I agree...Do it yourself. That's what I do. :cheers:

Yes, looks pretty simple. So why does the dealer say he needs to drop the exhaust to do this?

The procedure that the dealer is describing is the procedure for bleeding the clutch fluid via the bleeder valve on the clutch. To do this you need to drop the exhaust at the catalytic converters. It is true as the bleeder valve is located in a somewhat hard to reach location. Here is the procedure from the service manual.

Bleeding the hydraulic clutch system is necessary whenever the level of fluid in the clutch master cylinder reservoir has been allowed to fall so low that air has been drawn into the master cylinder.

• Clean all dirt and debris from the clutch master cylinder cap to ensure that no foreign substances will enter the system.
• Remove the clutch master cylinder reservoir cap with diaphragm.
• Fill the clutch master cylinder reservoir with clutch hydraulic fluid GM P/N 12345347, (Canadian P/N 10953517), or equivalent, if necessary.
• Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
• Remove the catalytic converter. Refer to Catalytic Converter Replacement in Engine Exhaust.
• Remove the driveline tunnel closeout panel. Refer to Driveline Tunnel Closeout Panel Replacement in Propeller Shaft.
• Have an assistant depress the clutch pedal fully and hold.
• Loosen the bleeder screw on the clutch actuator cylinder to purge air.
• Tighten the bleeder screw.
• Release the clutch pedal.
• Repeat steps 7 through 10 until all air is completely evacuated. Check and refill the clutch master cylinder reservoir with clutch hydraulic fluid GM P/N 12345347, (Canadian P/N 10953517), or equivalent, as necessary in order to prevent air from being drawn through the clutch master cylinder.
• Fill the clutch master cylinder reservoir with clutch hydraulic fluid GM P/N 12345347, (Canadian P/N 10953517), or equivalent, if necessary.
• Install the driveline tunnel closeout panel. Refer to Driveline Tunnel Closeout Panel Replacement in Propeller Shaft.
• Install the catalytic converter. Refer to Catalytic Converter Replacement in Engine Exhaust.
• Lower the vehicle.

Roger that. Thanks for all the info. Think I'll save $300 and do this myself.

Quick question. What would happen if air did get in the system? Would the clutch stick on the floor?

Clutch pedal spongy and or low effort is the symptom in the manual that prescribes bleeding the system to purge air from the fluid.

The pedal sticking to the floor is more likely a problem with the Master cylinder and typically caused by contamination causing the clutch to bind.

I had trouble with my clutch. I used Rangers method and changed my fluid 3 times in one week, the fluid stayed clear after and my problems went away. I now change the fluid 3 times a year and no more problems. This is a cheap maintenance.:thumbs:

my clutch fealt alittle strange/spongey and I also wanted it flushed and blead. Mines and 08 with 7k on it. I had it at the dealer for an oil change and mentioned that the clutch fealt alittle soft and i thought it needed to be flushed. Their mechanic agreed and it was done under warranty. Reading above that the exhaust had to be dropped I'm wondering if they really did it that way or what. I don't knwo if it was in my head or what but it does feel better now.

I do Ranger's method every few months and it always feels better when I'm done. :thumbs:

Clutch fluid change
 

Here in Florida humidity I change the clutch fluid using the "Ranger Method" every 3000 miles and with 59k miles on my 2005 I have not had any clutch pedal issues.
All the positive comments you have seen about the "Ranger Method" are true. One additional suggestion is to make sure that you cover all painted surfaces to prevent any fluids from coming in contact with your paint job, since the fluid is very caustic. I have a towel with a small slit cut in the middle so the reservoir can fit through the slit and the rest of the towel lays on the surrounding surfaces.
Good luck and take your time.

Mike

Hope this helps!

Hi all
Mine was not done for a long while. Was very dirty so i have been doing it a lot using ANSOIL DOT 4 in the clutch and AMSOIL DOT 3
for the brakes all working much better both can be done in less then 10
minutes DO NOT Drain The Brakes Dry keep it above the bottom
you will have no trouble Be careful not to spill any brake fluid on anything Good luck :flag::flag:

Clutch fluid is the same as brake fluid in that it is hydroscopic and will absorb moisture which lowers its boiling point. This can be seen on the graphs in the below links for the AMSOIL brake fluids mentioned above.

It has also been my experience in both my 02 Z06 and my 06 CTS-V that the clutch fluid gets extremely dirty extremely fast. One method to keep it fresh without going through the trouble of the bleed is the turkey baster method. Just suck out the reservoir and refill with clean new fluid. Repeat (often) as necessary until it stays clean. Note that this method won't really get entraped air out of the system so a bleed is better, but this is a really easy alternative. FYI, I use AMSOIL's DOT 4 in my brakes and clutch for my track duty Z06.

AMSOIL Series 500 High Performance DOT 3 Brake Fluid (Product Code BF3SN)
AMSOIL Series 600 DOT 4 Racing Brake Fluid (Product Code BF4SN)
Dry Boiling Point - 580F, Wet Boiling Point - 410F
:cheers:

I was clueless about the clutch fluid til a friend mentioned that he had just changed his. I followed Ranger's procedure. My 08 has 6600 miles. Bought a bottle at the chevy parts dept. I was quite nervous about getting any fluid on the car so I covered everything double with our blankets (my wife loved that). After 3 flushings it appeared to be clear. I was just so surprised how much easier and smoother the clutch was. Hard to believe changing the fluid made such a difference. Thanks for everyone's advice.

I don't know if you would be needing this service if you keep the fluid changed in the reservoir as "Ranger" says to do.....that's what I do....mine was black after only 1200 miles on my 'Z. I changed it five times using the directions on Rangers post. Finally it cleared up....I have not had any issue. I check it monthly now. Whenever it begins to get dark I change it. :thumbs:

The only disadvantage to the "Ranger method" is that it does not remove fluid in the slave cylinder, except to the extent that this fluid may mix with the rest over time. A dealer cost of $300 is unreasonable. It should take your dealer about 1 to 1.5 hours labor plus $10 for a can of fluid - say $100 to $150 total.

My clutch fluid appeared to be clear after 3 cycles but its possible that it will turn darker after a few days of driving as it mixes with the rest of whats in there. I read somewhere that the fluid may not necessarily be bad just because its dark. I may do a quick flush every few months anyway.

yes sir, :iagree: That's why I had to change mine five times (since I first did it, it's actually been six times now-cause it mixes). After I finally got it clear and have driven my 'Z for nother 1k miles, it's now gray.....I will change it again when I do my first oil change. I use DOT4 full synthetic....Ranger says any DOT4 is fine.....all they had in DOT4 at auto store was Prestone brand....which WalMart had for two less a bottle.....so I bought two bottles there. Did not quiet use up first one but discarded it. After it's opened should date it because of humidity so if I open a bottle, I only hold on to it for 30 days and chunk it. I caught my 'Z's early on before any problems occured though.....:thumbs:

If you read how the clutch hydraulics, you might change your mind.

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How the Clutch Hydraulics Work
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It’s always a good idea to go to the source document for a definitive description of the operation of the clutch hydraulics. In this case the Corvette Service Manual 2006, Volume 3, page 7-360, and I quote:

The clutch hydraulic system consists of a master cylinder and an actuator cylinder.

When pressure is applied to the clutch pedal (pedal depressed), the pushrod contacts the plunger and pushes it down the bore of the master cylinder.

In the first 0.8 mm (0.031 in) of movement, the recuperation seal closes the port to the fluid reservoir tank, and as the plunger continues to move down the bore of the cylinder, the fluid is forced through the outlet line to the actuator cylinder mounted to the driveline support assembly.

As fluid is pushed down the pipe from the master cylinder, this in turn forces the piston in the actuator cylinder outward.

As the actuator cylinder moves forward, it forces the release bearing to disengage the clutch pressure plate from the clutch disc.

On the return stroke (pedal released), the plunger moves back as a result of the return pressure of the clutch.

Fluid returns to the master cylinder and the final movement of the plunger opens the port to the fluid reservoir, allowing an unrestricted flow between system and reservoir….

Close Quote. There you have if from the source.

Summary: Clutch fluid circulates between the master and actuator (slave).

Note: The volume of fluid in the entire system is a very few ounces. One ounce in the master cylinder reservoir until diminished as you depress the pedal and create the flow described above.

Three to five swaps of the reservoir together with the pedal pumps (full-top to full-bottom to full-top) will thoroughly clean the hydraulics. Goal is to stay far ahead of the ingestion of clutch dust.

Ranger