Clutch problem advice please

I took my NSX out for a run ( to a Porsche Club meeting!!), and unfortunately when I got in the car to go home, the clutch pedal went straight to the floor and I couldn’t engage any gears. A helpful enthusiast suggested that I pull the pedal up manually which I did, and by pressing it very gently I was able to engage the gears, just enough to get me home with only 2 gear changes on the way. If I pressed the pedal too hard, the clutch was lost and I would have to pull it up manually with my foot.
I am not a born mechanic, so the car is booked in to be sorted next week. ( the garage owner has his own NSX.)
Can someone make some suggestions as to what the problem is likely to be? The car has done 87000 miles and had a new clutch at 67000 miles. I can’t see any evidence of leaking fluid.
Any thoughts appreciated.

I had the same issue a few ago.
Almost certain it will be the slave cylinder.

Agree with Pride, I had the same issue a couple of years ago. It was the flexible hose joint at the slave cylinder, the crimped end of the hose was corroded. Easy fix.

Best change the hose, slave and master cylinders all together if never been changed before.

Seems like your NSX is already booked in for the service and the garage owner has NSX so that would help a lot.

Could be already on the way to the garage so possibly too late and you'll get the same advice below any way but someone may experience the same issue in the future.

In case you are hoping to find a way to drive to the garage with potential temporary fix, please use the following as the guidance only.


From what you wrote in OP, most likely Clutch Hydraulic System (CL Hyd Sys) failure.

Whether you can drive the car or not to the garage depends on how much air you let into the Hyd Sys and/or the level of damages for the case of hose/pipe failure.



1. Check fluid level at the CL reservoir

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Check the fluid level marked in yellow.

Most likely, the fluid level is close to the bottom or empty.

If not, you have mechanical failure and needs further inspection on the Gbox side.


Both the CL master and slave cyl go through the same number of strokes/travels when the CL pedal was pressed and released.

However, almost all of the 1st sign of failure happens at the Master cyl side.

Because the fluid doesn't leak outside, the owners just don't recognise it until the major leakage happens at other places such as the CL hose, Slave cyl, etc.




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Crawl into the pedal area and look above the CL pedal or beyond the pushrod like in this photo.




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Unlike this photo, the black rubber cap where the pushrod enters should be dry or may look just wet around the pushrod body due to the grease.

No fluid should be dripping at the cap.





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If you see fluid at the rubber cap, I'm afraid fair amount of brake fluid were dripping on the floor carpet over many years.



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By now, the sponge like material behind the carpet would become bit and pieces after being exposed to moisture/brake fluid/etc.

Still, you want cleaning as much as possible to remove the brake fluid from there.



2. Look for wet markings on the garage floor.
The CL hose and the slave cyl are located near the Rear Left wheel.



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The hose entry is connected to the pipe mounted next to the eng bay firewall and the exit is connected to the slave cyl that is bolted to the side of the Gbox.

Not easy to see without shifting the coolant tank and the bottom side of air box but try looking below the eng bay fuse box and the area below the 3 x big coolant hoses.




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If major leakage from these hardware, you would see brake fluid dripping or splashed around the area marked in yellow.


The seepage at the crimped section of the hose could run along the hose body and land on the shift cable housing below the slave cyl.

If you have early year model, the dust cover surrounding the CL slave cyl has no opened section unlike the later spec.

Because of this, the seepage could take some time before you notice it so pay extra attention around the dust cover.



3. Temporary fix
If the slit/hole at the hose or pipe is small enough, you may be able to patch it using the self-amalgamating tape after creating clean, oil free and dry surface.

Though, may not be easy with limited space available.

If there is no major leakage at the hose or the pipe described in #2, the piston cup/seal at the master/slave cyl could survive for a short driving.

With major leakage, unless you can fix it, probably best if you flatbed the car to the garage.
There is a way to shift the gear without disengaging the CL and as used in emergency escape method, you can move the car using the starter but that will be the last resort.


You need to figure out the amount of air trapped inside the Hyd Sys.

As you were able to at least get to the car event, you may caught it in time and may be able to rely on self-bleeding method.

Otherwise, you'll need to properly bleed the air.

If the fluid level is empty based on the check in #1 and if you don't have spare brake fluid, look at the fluid level of Brake reservoir and the ABS
(if your NSX has the classic ABS with dedicated reservoir for the ABS and not the latest one body Bosch style ABS).

CL reservoir only needs small amount of the brake fluid so you could transfer some of the fluid from the two reservoirs mentioned above.

On street, you can safely operate the main brake system with just the 1/2 level at the brake reservoir.

My NSX is set there for years with several 10K miles covered.

Or, just get some brake fluid.


In emergency case, I even used green tea when my friend's NSX was stranded in the middle of mountain road with no mobile coverage and in the dark night.

You can find soft drink vending machine everywhere in Japan so easy to get any water, etc.

It's not brake fluid but the CL line won't get boiling hot and it won't corrode the brake pipe internal surface if flushed within a short period.

Used the self bleeding method below, managed to recover the pedal operation, drove back and within a few days, the system was flushed multiple times to get rid of any moisture inside the pipe.

The CL master/slave/hose were replaced as a set as the golden rule.


4. Self-bleeding method.
If you caught the issue in time and only small amount of air trapped, you may be able to recover the pedal operation by the following method.

After carrying out this method and leaving the car overnight may even help self-bleeding further.


Fill up the CL reservoir.


With your finger, pinch and release the reservoir hose leading to the master cyl body many times.
This is to prime the piston.
You should see small bubbles coming up to the reservoir fluid surface.

Tapping on the master cyl body with soft mallet will help the process.
Keep doing this until no further bubbles coming up.


Make a note on the fluid level.


Now make sure to close the cap.
This is very-very important.
Otherwise, during the next process, you could splash the fluid all over the place under the bonnet and it's the brake fluid.


Get inside the cabin and operate the CL pedal with your hand.
At first, when pressing down towards the floor, you won't feel any resistance so be gentle.


When lifting up the pedal from the floor, try to flip it up to generate big shock/impact.
This will help move any bubbles inside the Hyd line.
Repeat this like 50 - 100times or until you start feeling some resistance when pressing down on the pedal.
If you can't feel any resistance (generate pressure), I'm afraid you allowed too much air into the system that you must bleed the air manually and not rely on the self-bleeding method.


Once you can start building up the fluid pressure and the pedal can return to its rest point without your hand assistance, check the fluid level and top it up close to the top, exceeding the max level.


Make sure to close the cap for the same reason as above.


Now you can start using your foot instead of the hand.
Press down on the pedal at fast speed to the floor end stop, like kicking at the pedal.
Then, instead of lifting your foot upwards, slide it side way.

It's like kick at the pedal to the floor and slide your shoes side way afterwards.

This will generate huge impact/vibration to the Hyd Sys promoting the self-bleeding.


Repeat this kick and slide operation at least 100 times.
If the seal/cup were not too damaged AND if you didn't let too much air, you should be able to bleed the air out of the Hyd Sys.



Hope you can get to the garage.

As NSXGB mentioned, please replace the CL master/slave/hose as a set.


Kaz

Thanks for all your advice- I will pass it on to the garage. I have arranged to have the car lifted to the garage to avoid any more damage.

Conclusion! Eventually got the car lifted to the service garage and as suggested, it was the slave cylinder. Now awaiting a replacement.
Incidentally, when I took the car in, the garage was fitting a new fuel pump to a 2003 NSX, yellow, with 16000 miles on the clock- absolutely immaculate. Part of someone’s fine collection!