Hi, I have searched and read many threads before posting, but my diagnosing is going no where. Even after a visit to the mechanic. Going to describe the events and hope someone has an idea.

Car: 2011 G37S Sedan RW 6MT - Original Clutch, Slave, Master, and Lines (lives outside in Canadian Toronto Winters, so the typical surface rust everywhere underneath)

May 23, 2022
* When coming up to a light with the clutch depressed I had the windows open and no music and heard a pop at the time it sounded like running over a plastic bottle and the cap popping off. This may have nothing to do with anything but that's what happened. The car drove home fine after that.

May 24, 2022
* Next day, got in the car in the morning and noticed that the first 2" of travel in the clutch pedal had 0 resistance but the pedal would come back. My engagement point also moved closer towards the floor.
* Drove home from work same symptoms.
* Popped the hood at home and saw that the clutch fluid reservoir was empty (recently empty, nice and clean but moist).
* Inspected from reservoir to master, around the master pedal plunger inside, from the master to the transmission cover and couldn't find any leak
* Read up a ton of threads on the forums and discussed with my buddy who owns the a coup G37S and we both suspected the slave
* Called my mechanic got a quote on Clutch + Slave, he couldn't take it for a week so it sat in the driveway

May 30, 2022
* Got in the car and now the pedal felt no resistance to the floor and the pedal stayed there
* Got it towed to mechanic

May 31, 2022
* Mechanic calls me that he can't find a leak, removed the cover on teh transmission and reached in there but could not see any leaks
* He filled it up with more fluid, bled it a bit and it was working, doesn't feel right about doing the clutch/slave without knowing that's the problem 100%
* Suggested we drive it a bit more and introduce more leaks so he can be sure

Jun 4, 2022
* Went by my mechanic this morning, when I arrived the first 2" of clutch pedal again had no resistance but this time it returned after I used it 5-10 times. Drove the car around for 1.5 hours and must have done 2000+ clutch depressions, it wouldn't fail in any way felt like it used to
* Spoke to mechanic, he said take it home drive it till it fails, took it home and once I got on the freeway for about 5km by the time I was getting off the freeway teh pedal had no resistance and it was staying depressed. Fluid in the reservoir remains full though, and not empty. I figure the high frequency vibrations at high speed caused it to fail vs my neighborhood driving for 1.5 hours this morning.

Looking to see if anyone here has any ideas other than slave, I am willing to pay for the work but would feel stupid doing it only to not fix this issue. It always feels **** not seeing the actual problem and throwing parts at it.

* Why did the reservoir go empty last time it failed, but not this time?
* Why would the mechanic not be able to see the leak in the transmission where the slave is located?
* Could it be anything other than the slave which I can inspect?

Sorry for the diary entries and thank you for your time.

 

There is no "cover" for the transmission that a mechanic could just take off to reach in and feel around for a leaking CSC. He would have to drop the entire transmission. That being said, I'm guessing a leak in the CSC would probably drain out of the bottom of where the transmission mates up to the engine, because it's not really an airtight seal, so maybe that's what he was referring to, or maybe he's just giving you the runaround. It seems that either your CMC is bad, your CSC is bad, or you have a leak in the clutch line somewhere.

 

Thanks for responding, unfortunately cannot see a leak anywhere from CMC all the way to transmission housing where the bleed nipple is. So I'm thinking CSC since I should be able to see wet brake fluid somewhere. I'll take it back in and start with changing CSC and clutch. Original clutch on 165000 km, will suck if it's not that but at this point I'm not sure what to do.

 

Incorrect. Every manual gearbox will have some type of inspection hole in the case. Here is a pic from a G37 6MT and you can see the "dust cover" over the access hole:

OP, if the CSC seals have failed, you will have some brake fluid residue along the trans case. If the case is "bone dry" then either the master cylinder has failed or there is a small, external leak that you just haven't identified.

I just went through this ordeal on my old beater pickup. Turned out the piston seal in the master had failed causing fluid to leak out.

Good luck!

 

If I recall correctly, that is a small dust cover where the clutch fluid line runs through the transmissions bell housing (case) to the CSC. I don't recall if it's even possible to remove that dust cover from the outside, but even if it is, it's certainly not large enough to reach into and feel around, and it's high enough in the transmission tunnel that you couldn't stick your head up there and even look into it. At best, you might be able to remove the dust cover and then stick a camera through that small hole.

 

I believe Infiniti recommends replacing the CMC too when you're replacing the CSC, so you should probably do that as well while you're at it. You'll likely need to replace the clutch, pressure plate, flywheel, pilot bearing, CSC, and CMC.

 

Mechanic probably checked through the small black dust cover (by flywheel).simple screwdriver can removed that. I would agree it could be the master. You should probably check inside the car on your carpet or right behind and above your clutch pedal to see if you have oil leaking inside instead of the transmission.

 

Thank you all for the feedback. Took some pictures inside the case through the rubber cover.. Sorry for posting that many.

• No puddle which i would expect from a whole reservoir emptying the first time
• Everything does seem kind of like it has a wet look
• Rubber seal looks like it's not seated properly

Does this wet look and seal condition confirm anything to any of you? Would that seal going over that lip coincide with that pop I heard the day before I noticed my clutch has issues?

 

It's hard to tell from the photos if it's wet inside or not. But maybe a mechanic can tell with photos like that (there's no way he stuck his hand inside).

I would think a leak at the CSC would drip out of the bottom of the transmission bell housing because I don't think there's a waterproof seal when bolted down to the engine. There's no gasket between the bell housing and the engine. The boot on CSC does look like it's a little wonky, but I think it's just a dust boot and probably doesn't have anything to do with it leaking fluid.

 

This is CSC failure. Pay attention to the soaked part.
Engine oil would have been able to be seen everywhere and it would have killed your clutch already. Brake fluid since it's water soluble it can wash off a bit making it harder to diag.

Once you fix this you should also replace the clutch reservoir hose which is what kills them prematurely, hose starts decomposing killing the rest.

 

^^Can you circle/highlight the soaked part?

 

 

^^You look at xrays often?

 

Thabk you for taking the time to look at the pictures. Yesterday was a very hot day and pedal was failing while driving home from work and I noticed wetness at the reservoir and hose. Is this from me pumping the pedal non stop to get it pressurized or is this possibly my main leak and entry point of air.

 

Was the CMC reservoir empty when you checked it (meaning that air had been able to enter the system)? If it was empty, then the problem could be anywhere (the CMC, the line leading to the CSC, or the CSC). If there was still fluid in the CMC reservoir then that fluid you see on the hose might be from overfilling it, and I would guess your problem is either the line leading to the CSC or the CSC. Did you check to see if any fluid was leaking out of the area where the transmission bell housing mates up to the engine?