What would cause my clutch oil to be low?
 

I currently have 25k miles on my 2015 370z Sports Tech. A couple of days ago I noticed that my clutch pedal felt very light when initially pressing on it, and then maybe 10% down I would feel pressure like it's supposed to.

I checked my clutch oil (brake fluid) and it was right below minimum. I check the area and I don't see any leaks.

What would cause my oil to go down that low?

Photos:

https://imgur.com/a/pktsVpF

Your Clutch Slave Cylinder (Aka CSC) is leaking. It's not oil by the way, It is brake fluid. Have it changed out to Motul RBF600 dot 4 brake fluid for longevity sakes. When it get's dark, do a fluid exchange on it.

Thanks. Good to know lol. How can I fix the leak? I 'am getting the fluid changed tomorrow.

Have it changed tomorrow and monitor the level regularly. It's a common issue. If it continues to go down you will need to replace it. The CMC (Clutch Master Cylinder) can leak also. It will leak inside the car above the clutch pedal. It's not common but it does happen.

If you have the cash, install the Z1 CSC elimination kit or the Z-speed cmak. These will solve the problem permanently. I have the Z1 kit, but I've heard great thing about the cmak.

Can I just keep topping the brake fluid off if I use the same fluid?

Also is the CSC covered by warranty?

3yr/36k miles, Yes it is under warranty. Above that and it is on you. If you have a leak, the CSC will fail and will require a tow truck. It is only a matter of time.

It seems like such a common issue, I am surprised that Nissan hasn't issued a recall.

Are there any tell signs that its almost done? How much does it usually cost to repair?

If you replace it with another genuine Nissan oem CSC it will just fail later down the line. I know people here how have had their genuine Nissan oem CSC fail three and four times on them. Replace it with a Z Speed Performance CMAK kit as soon as you can before it is too late. Also the CMC can fail as well. The RJM Performance heavy duty CMC is very durable and I would say bullet proof.

Black chunks in the fluid is one sign. The cost to repair is going to be 5-8 hours of labor. Also, when the CSC goes, the fluid can leak all over the clutch and ruin the friction material, so it's possible that you'll have to replace the clutch as well.

I have had 2 different Nismo 370's, I am at 72k on my current one and had over 60k on the one that was totaled. They are both still on the stock CSC. So, it's not that bad.

I suspect a lot of the people who deal with premature CSC failure are in stop-and-go traffic, and push their clutch pedal all the way to the floor.

I hear ya. I am not sure what is the deal.

Mine is at 70K and so far no problems. If it went tomorrow I'd consider my self blessed to have had it problem free for so many years. I mean, mine is a 2009!
Of course I keep the revs down and have never even gotten close to rev limit.
Sad, I know, but that's just me. I got all that out of my system many years ago.

Yep, from what I've gathered so far, the stock CSC requires a little sensitivity from our left foot. Avoid slamming on the pedal fast/hard and avoid pressing it all the way down seem to go a long way. Mine is 09 at 35k, no problem yet, knock on wood.

Pretty much how mine went,

I am all over the rev limiter all the time. LOL That's not the issue.

I gorilla mine. :driving:

I sometimes think that Nissan has 2 separate parts bins for the CSC. One with good CSC's and one with bad CSC's that have been rejected at QC. Every once in a while. The guy who is installing them will grab bad CSC's from the bin of rejects when the good bin is empty and install them instead.

I actually never had an issue, I just got lucky and won a Z1 Clutch, unsprung hub, light weight flywheel and CSC Elim kit at the Z Nationals last year. But to be totally transparent, my Z only has 22,000 miles on it.

On thing I do not do and that is idle with the clutch depressed in stop and go traffic.

Stay off the clutch as much as possible. That's what my Dad always said when he was teaching me to drive many years ago.

Spartan your dad is a smart man. Although its hard when you want to bang around gears in a Z.

Anyway folks, it happened. The clutch engagement dropped to 50% and then at a red light it stayed on the floor. Had to get towed. A little upset because it messed up the paint on my freshly painted AeroWorkz lip and put a little rash on my motordyne ( damn speed bumps).

Should I replace both the CSC and CMC to eliminate all risks of other issues?

I wonder how often the bearings go out, vs. the seal? I know that most folks here have the seal go out, but have any long-time forum members seen the bearing on the CSC go out?
Any bearing assembly has a limited lifetime of rotations designed in, so that's why I commented on keeping my revs low. I don't know how many that is, but since mines been rotating since 2009 must be a lot.
I do my best to push the car out of gear smoothly (without clutch) at red lights and stop signs so as to lessen the number of cycles I put the CSC and CMC through. I also do the ranger protocol often.

Note: I test drove a 2015 Carrera 4S manual the other day and Porsche design won't allow the stick shift to be "bumped" out of gear, the clutch must be fully depressed. Just something I noticed driving it.
Also didn't notice a great deal of difference between my Z and the Porsche other than the oh-so-nice interior.

I have to disagree with you on this one.... maybe the 996 c4s, but the 991.2 c4s is miles ahead of our Z in all aspects. Sorry.