2008 C6 hydraulic clutch problem
 

Hello,

I have a problem. My Vette is leaking hydraulic clutch fluid. The leak can be also observed on the gearbox case on the bottom.
Tech guys say it's the master cylinder. Anyone had this issue before?
Some friend said it is only the Pressure plate. He says he had the issue and this was the cause.
Other than that, the car runs fine. The gearbox works flawlessly, the stick goes easy in gear,even though sometimes when i release the clutch it gets quite a shock :-)
Any help appreciated.

If you are seeing brake fluid in the bell housing area, the slave is probably the culprid.

I suppose so. Is it a hard job? The local dealer asked me 500 EUros for the cylinder alone, without the labour cost, while on GM Parts House it's only about 200 dollars...

"The leak can be also observed on the gearbox case on the bottom"? The clutch and master cylinder are bolted to the engine bellhousing in the front of the car, the transmission is bolted to the differential in the back of the car.

The pressure plate doesn't have any hydraulic connections, it can't leak anything.

I didn't know the transmission was on the rear. It must be the engine oil pan then. The leak is indeed next to the bellhouse. So i order to replace the cylinder, what needs to be removed? I suppose it is inside the bellhousing!

There are two possibilities for fluid leaks in the bell housing area. It could be brake fluid from the slave cylinder, which is mounted to front of the torque tube housing (behind the clutch pressure plate), or it could be engine oil from the rear engine seal for the crankshaft (in from of the clutch/flywheel).

You mentioned oil pan. You should check to see if the leak is in fact coming from the oil pan area or possibly from around the oil filter.

Is the fluid level dropping or low in the clutch master cylinder? If that is the case, then it is most likely the slave cylinder/throwout bearing (it is one piece). Also, what is the nature of the fluid you are seeing? Does it smell like brake fluid or engine oil? How thick is it? Brake fluid is like water and engine oil will be more like syrup.

To replace the slave cylinder/throwout bearing or the rear seal on the engine is not a small task, as the transmission/differential must be moved backwards so that the torque tube can be removed to get access to the clutch/flywheel assembly.

In Canada the slave cylinder/throwout bearing costs about $450 CDN from a GM dealer.

Yes, the fluid level drops in the hydraulic clutch reservoir. That's why i suspected the cylinder. The engine oil level stays constant, and i have no problem with it.
i'll probably buy the cylinder from US and have it replaced here, since it would be cheaper than buying it from the dealer.
Moving back ... sounds quite a job. When the weather will get a little bit hotter, i'll inspect the "belly" of the car and see what's all about...

Depending upon the mileage of the car, if you are going to tear apart the drivetrain to replace the slave cylinder, you may also want to consider putting a new clutch in it while you have it apart.

That is an excellent suggestion, and it is exactly what I did when I had some transmission and torque tube issues. Went with a RAM twin-disc and their aluminum flywheel.......just do not use the RAM slave/throwout bearing. Had to replace mine in 7 months as it was free flowing brake fluid past the seals.

Personally, I think the GM stock slave/throwout bearing is one of the better choices.

While replacing the slave cylinder another one of those things you should do while you are in there is to install a remote clutch bleeder line. That makes it a lot easier to bleed the clutch if you need to at some later time. Bleeding the clutch without a remote bleeder requires removal of the exhaust and the tunnel plate. With the remote bleeder you don't even have to lift the car off the ground. For ~$110 US it isn't a bad investment.

Bill

AND damaging the insulation above it :yesnod:. At least on my GS. Tried to bleed it when replacing the '12 X-pipe for an '11 OEM one (no small cats), and the nipple was right against the insulation. Not even my finger fit in between, so even ripping the insulation would have been a hard job to fit any drain line in there.

By the way, the reported 'easier' method is to remove the intake, but I didn't want to do that on my new car. Plus the insulation would still be a problem. And certainly don't want any more heat in the interior that we already get. What I started doing from day 1 was to drain/refill reservoir. Have done that maybe 15 times in 3K miles, but that's no substitute for a proper bleeding IMO. I want to eventually do the job right somehow, to avoid having to buy a new slave prematurely.

Well, because practice makes perfect, the job of replace clutch, pilot, and slave isn't all the difficult after doing it once. I would recommend having a buddy around for sure.

To answer your question, to get to the slave assembly you have to pull the rear differential/transmission (which requires either dropping the cradle and then the trans/diff, or dropping it all together) with the torque tube down and then back at least a foot or so. You'll have to completely disconnect the rear shocks, control arms, a brake line, the ebrake lines, shifter through center console, 6-7 electrical plugs, calipers (I do this so I can remove the rotors for safety), and then the transmission cooler and clutch supply lines up front.

To be sure it's the slave, you might want to consider adding ATE Super Blue fluid to the clutch reservoir now. I run that stuff for clutch fluid and brake fluid. Now I have blackish=oil, red=tranny, brown=differential, pink/orangey=coolant (water wetter plus a little antifreeze), and blue=brake/clutch. Makes for easy diagnosis at the track for drips.

Holy crap! That's a major teardown just for a freaking slave. As complex as the Germans like to make things, replacing the slave on the M3 V8 requires all of 2 bolts. It already has a quick-disconnect line. This is ridiculous. And with so much labor involved, and the crappy slave with no dust seal, not adding a remote bleeder line from the factory is almost an insult.

Anyway, do you think doing the 'ranger' method since day 1 would prevent slave issues in the long run? If not, I better get that line bled somehow sooner rather than later. Only 3K miles on my '12, but I plan to keep this car for a while. Maybe 5K miles a year or so. Thx.

I'm sure the discussion of the "Ranger Method" can be argued subjectively both ways. I would offer the opinion that it would help keep the slave clean and make it last longer. However, if the slave has failed so soon...would cleaner fluid have really helped? Looking back at it all, I would've installed the remote bleeder as soon as possible and saved myself some issues. Just my opinion. To install the remote bleeder, the process is similar, but you don't have to pull everything out. Just far enough back/down to access the bleeder on the top. When I first installed mine, I didn't tighten the remote bleeder down all the way and found myself pulling everything right back out within hours of thinking I was done. I'm on 4 times in 3 weeks now...getting pretty proficient at it.

I was going to install a remote bleeder when we were doing the slave for the second time as the RAM slave was completely shot in 7 months and a newly re-built tranny was grinding second gear.........that is until we noticed a tag on the RPMTransmission level IV transmission that was going into my car that said installing a remote bleeder would VOID the transmission warranty.

I asked them "why". Their response made sense. They said that with a remote bleeder air can get trapped in the remote bleeder lines that will prevent the clutch from completely dis-engaging, causing shifting problems and premature synchro ring failure. They said the factory set up is self bleeding and works well. I also have a Tick master cylinder, and they knew that.

Needless to say, there is no remote bleeder on my car, and so far it is shifting like a dream. I'll just do the Ranger method to flush the fluid on a regular basis.