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  1. #1
    Member tim414's Avatar
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    Corvette(s)
    2010 '427' Z06 JetStream Blue

    Default Dirty Clutch Fluid

    I got into Vette this morning to drive into city for work meeting. First, when I was pulling out of drive way I heard a tapping noise that sounded like was coming from right rear. It sounded like a half shaft u-joint clapping/tapping metal to metal sound and was doing so as the revs of back wheel was (turning). Like it was going to fail/something about to come apart. Car at this time had 1064 miles on ticker. Went about 1/4 block and turned car around and went back home. Got to thinking, just go ahead and drive it....let it take a dump....that way I won't have to describe any noise....it's broke already (thinking to myself).....well drove all the way to Dallas (60 miles) and nothing. The noise stopped within moments turning out of driveway. I was turning the car right turn out of driveway when noise started. My driveway is long. I did not hear it when left out of my shop. Only driving out of my driveway pavement onto city pavement and heard it both times. Car had been running maybe 4-5 minutes, was warmed engine by that time. First time Vette driven in several days. Rear noise ended and did not occur again in next 120 miles.

    Got home popped hood and checked fluids and found my clutch fluid is BLACK. Only 1140 miles. Car has NOT been driven hard at all. I wonder if it's the way I drive? This is my second car w/clutch. Total exp w/clutch 11 months.....maybe I should work on my shifting technique????

    Anyway, I understand to empty resveroir and refill w/dot 3 fluid is it??? Which is best brand for hot climates??? This Texas heat could have something to do with it, could not?? Anyway, the car has not been driven hard at all, trying to get it broke in good before WOT's etc.... Scouts honor....I've read that Z06's clutch fluid gets dirty easy too....is that correct? For sure, with only 1100 VERY EASY miles my clutch fluid is BLACK. only two months since got it..... Somebody please let me know which is good clutch fluid for hot climates for my 'Z....thanks

  2. #2
    vett boy's Avatar
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    2008 vert 6M silver

    Default

    I changed mine at 3000 miles the first time and then every time I change my oil .I change my oil @60-70%.

    Pretty simple just use a Turkey baster ,get all you can ,re-fill and pump the clutch.Do the procedure three times .You won't get it all out but enough .I use Valvoline (sp?)

    Most importantly rinse the turkey baster well before your wife catches ya.

  3. #3
    Member
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    2006 C6Z DSOM

    Default

    OP~ I can't say what your "noise" is but chances are, it's the clutch packs in the rearend. There's a TSB for this.

    The clutch resevior under the hood is a different issue. As vett boy stated above, to minimize "sticking clutch pedal" syndrome, you might want to change the res fluid often. The fluid oxidizes because the line from the rez to the slave passes too close to the exhaust manifold. There is no fluid that doesn't turn black. There are some fluids that last longer than others, but the problem remains. Insulating the fluid line is a big help, but it isn't a cure.

    Ranger on CF has a good bit of info on this.

  4. #4
    Tuna's Avatar
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    '13 427 60th

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    Black fluid - my 2008 did that and around 11K miles, the clutch went to the floor and stayed there. New clutch, master and slave cylinder and fresh fluid later, it was back on the road.

    I'm not sure if the 'black' fluid is the problem or the slave cylinder that allows the fluid to go black. Either way, I was not happy.

    I've got 25k on it know and it's still working.
    Tuna
    NCM Lifer - NCM Fighter Squadron
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  5. #5
    Technical Advisor c4c5specialist's Avatar
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    Nope, but someday.

    Default

    Hi there,
    Clutch fluid does 2 things.

    Transfers pedal pressure to the slave cylinder.
    Lubricate seals and pistons.

    The blackness is carbon black that leaches from the rubber seal into the fluid. It does not cause the sticking pedal condition nor does it create reliability concerns.

    The problems occur when the lubricity of the fluid is NOT adequate the either lubricate or the moisture contamination boils the fluid due to excessive heat.

    There are at least 3 different reason for the clutch pedal sticking.

    None of them are for clutch fluid that is turned black.

    Clutch pressure plate finger installed height differences or clutch material on the concentric slave cylinder creating a binding condition.

    The last is fluid boiling.

    This is one of the largest reasons why people need to be educated as to the correct service intervals that GM released a while back.

    Every 2 years, the clutch fluid should be changed with DOT 4 Brake fluid.

    And your noise is most likely the differential.

    Allthebest, c4c5
    GM World Class Certified Technician.
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  6. #6
    Member motorman's Avatar
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    if you have a bike or quad with a translucent brake master cylinder you see the same thing,the fluid turns dark in a short peroid of time. i have heard it come from the mold release used for the rubber parts and that is the same reason your tires turn brown
    retired race engine builder,former NASCAR tech inspector,corvette owner since 1959, new corvettes owned,59,62,63,64,65,66,97,99,02,05, 2008 is in my garage, 2008 sold and waiting for my C-7

  7. #7
    Member tim414's Avatar
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    2010 '427' Z06 JetStream Blue

    Default

    Quote Originally Posted by c4c5specialist View Post
    Hi there,
    Clutch fluid does 2 things.

    Transfers pedal pressure to the slave cylinder.
    Lubricate seals and pistons.

    The blackness is carbon black that leaches from the rubber seal into the fluid. It does not cause the sticking pedal condition nor does it create reliability concerns.

    The problems occur when the lubricity of the fluid is NOT adequate the either lubricate or the moisture contamination boils the fluid due to excessive heat.

    There are at least 3 different reason for the clutch pedal sticking.

    None of them are for clutch fluid that is turned black.

    Clutch pressure plate finger installed height differences or clutch material on the concentric slave cylinder creating a binding condition.

    The last is fluid boiling.

    This is one of the largest reasons why people need to be educated as to the correct service intervals that GM released a while back.

    Every 2 years, the clutch fluid should be changed with DOT 4 Brake fluid.

    And your noise is most likely the differential.

    Allthebest, c4c5
    Thanks Paul. Should I take it to dealer now or wait and let things develop (regarding diff)??? I drove it to Dallas and back yesterday and as far as I know it's not making any noise. I did not find any oily spots on shop floor either. (Just a/c condensation) I have noticed something strange but blew it off a couple weeks ago that the '09 Z51 Roadster did not do. It was a strange noise, very brief, so I blew it off. Will/could it leave me walking???

    I will go ahead and change clutch fluid because I had the resv. top off yesterday....and I live in a humid enviroment and possiblity that condensation could develop causing boiling in this heat we have here. (I would like to live up North during this time/year). I read the service bulletin (as well you just said) to change fluid every two years. I will do so afterwards. I did not know that the fluid did not return to reservoir. Makes sense. There's another reason I got confused about it but I will be politically correct. Tell ya in pm. Thanks Paul. Tim

  8. #8
    Member tim414's Avatar
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    Corvette(s)
    2010 '427' Z06 JetStream Blue

    Default

    Quote Originally Posted by motorman View Post
    if you have a bike or quad with a translucent brake master cylinder you see the same thing,the fluid turns dark in a short peroid of time. i have heard it come from the mold release used for the rubber parts and that is the same reason your tires turn brown

    Wow thanks for info, that's what C4C5 said also....must be gospel....

    Thanks for all replies....tim

  9. #9
    Member tim414's Avatar
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    2010 '427' Z06 JetStream Blue

    Default

    Quote Originally Posted by c4c5specialist View Post
    Hi there,
    Clutch fluid does 2 things.

    Transfers pedal pressure to the slave cylinder.
    Lubricate seals and pistons.

    The blackness is carbon black that leaches from the rubber seal into the fluid. It does not cause the sticking pedal condition nor does it create reliability concerns.

    The problems occur when the lubricity of the fluid is NOT adequate the either lubricate or the moisture contamination boils the fluid due to excessive heat.

    There are at least 3 different reason for the clutch pedal sticking.

    None of them are for clutch fluid that is turned black.

    Clutch pressure plate finger installed height differences or clutch material on the concentric slave cylinder creating a binding condition.

    The last is fluid boiling.

    This is one of the largest reasons why people need to be educated as to the correct service intervals that GM released a while back.

    Every 2 years, the clutch fluid should be changed with DOT 4 Brake fluid.

    And your noise is most likely the differential.

    Allthebest, c4c5
    Sent you a pm. Thanks Paul

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