Not sure how many miles you put in during the 6 mos period, but the clutch fluid should not be very dirty. It may be that the internal seals are wearing prematurely and caused the fluid to turn black.

The csc was replaced by the dealer under warranty 18 mos ago with 10k miles. The fluid is still very clean (golden clear color) and the clutch is working well.

just to add a little fuel to these fires.....

the crummy CSC/hydraulic clutch system in the 370 is one of the MAJOR factors in me selling my nismo. i had the car 4 years. i went thru the first CSC in 24k miles. the dealership even said my clutch looked great with zero abuse.

i babied that car, and i babied it after i had the CSC replaced. The nismo was my daily driver which it can do perfectly fine as long as you dont drive the car aggressively. but who the hell wants one if you are too scared to break it???

i sold it at 69k miles. i wouldnt be surprised if the next owner gets 5/10k fun miles before it all breaks again.

driven hard these "OEM" systems will only last a year. babied you can get away with several more.

Lest we forget that MOST(not all) dealer techs are guys who have graduated from the oil change department after taking a year of vocational and a two month "factory training" course on how to use consult3, they know enough to fool you but when something actually goes wrong they end up calling nissan tech line about it because they don't OR AREN'T ALLOWED to actually fix what is wrong. They have to follow Nissan procedure which is only in place to keep nissan from having to spend too much by actually warrantying what is broken. And the service writers are just salesmen they don't chit 3/4 of the time.

I noticed on/off feeling you mention when I did a flush months ago to recover from an un-drivable situation. The flush made all the difference. I also looked at the heat wrap option. It's interesting to hear that wrapping the tube solved your problem. It's pretty clear that it was in fact heat related. Did you have another OEM unit installed?

The CMC and CSC are really simply parts with metal rods and rubber seals. I think the issue with the z is that the CSC in situation inside the transmission where the heat is much higher and worst of all, the labor cost involves in replacing it because the trans has to be removed.

I replaced my Miata's CSC (external mount) in about 45 min. and the part cost $40.

Update:
 

UPDATE:

Dropped my Z off this morning at the dealer. Just got a call stating that they noticed insufficient heat shielding on the clutch line and damage to the heat shielding around the CAT.
They flushed the clutch fluid, which was completely blackened, checked the system for leaks (none were found), addressed the clutch line shielding, and are replacing the CAT under emissions components warranty.
I get my car back this afternoon. We'll see how it feels. $0 charge for services. :)

It seems that the last time the CSC was replaced, it was not buttoned up correctly which over time led to the problems.

Who knows. I am already looking to get the zspeed unit because, YES, I know this will fail again at some point... I have a 3rd party warranty with a $100 deductible that I used to get the first CSC replaced. I asked the dealer if they would install the zspeed unit instead of the OEM unit WHEN my current unit fails if I supplied it.
They didn't think it would be a problem, but they would have to document to the warranty company that a non OEM part was installed, which may void any further warranty service on that part.

...That's fine by me. :) I will just make sure they replace the master too.

If they have a problem installing a non OEM part at the dealer, they said I can have the work done at another shop that accepts warranty claims.

Hopefully that won't be for a while yet.

Wow... black clutch fluid with no system leaks and they replace the catalytic converter? Sounds like a typical dealer experience :ugh2:

Btw I have over 10K miles in the Texas summer sun without the clutch line heat shielding. No issues whatsoever.

Got the Z and drove her home. Clutch feels perfect. Very tight and consistent the whole drive, which included about 15 miles of freeway. I didn't notice any of the symptoms that I previously had, just like the last time I did the flush. Hopefully this time it will last longer.
:tiphat:

It's funny how you Yanks get all the dodgy Z's :stirthepot:

It's not a coincidence. My theory is Japan still holds a bit of a grudge.

i agree,

japan got payback, no cool cars under 100K