DC5R Clutch Pedal Sinking

[eLtrix]

So was cruising with a few mates and suddenly my clutch pedal sunk to the floor. Thinking great my cmc or slave just died, so I pulled over looked for leaks and checked the reservoir level. I could not find a single leak nor could my mates who were with me and the reservoir level was still high, no signs of it leaking or being drained.

So I turned my car on again and what do you know? My pedal is FIRM again. Thinking it was okay but still risky I ventured on home monitoring the clutch pedal. Here are a few things I noticed:

-Taking a left turn made the pedal go softer and sink, then going back straight it would go firm again
-When sunk could not change gears at ALL but could accelerate fine
-Alternates from soft and firm randomly
-When it sunk to the floor I could quickly put my feet under the pedal and flick it up and It became firm again - meaning I could change gears once again

I made it home safe and sound praying to god I didn't have to get towed home.
Right now she's just sitting in the drive way and I'm just brainstorming and googling ideas what could be wrong.

If you guys could put in some input would be great!

Thanks!

[knobosaurus]

Could be talking out of my butt here but does the clutch also have a vacuum reference like the brake booster too? If your system is leak free it might be that. Otherwise youe clutch pedal assembly could be damaged or loose. Did you pop ypur head down near your clutch pedal and lool at the firewall penetration? Any fluid leak there?

[Timmy_B]

If you can not see any leaks or damage to cmc try changing the fluid and bleeding the system.

[tinkerbell]

If you can not see any leaks or damage to cmc try changing the fluid and bleeding the system.

this is step 1.

but there is no reason why going left should have anything to do with anything.

[rookie]

.... there is no reason why going left should have anything to do with anything.

This is exactly my thought. It's a hydraulic system, I don't understand why moving in any direction would effect the pedal movement at all.

Have you looked on the inside of the cabin at the clutch pedal for leaks? Also like knobo mentioned, make sure you check the clutch pedal assembly and make sure its not loose or a bolt hasn't broken.

[tinkerbell]

This is exactly my thought.

and believe me - i did think about it for a few minutes!!!

[sleepingperformance]

Could possibly be a pressure plate issue, as the prongs are not bouncing back out. If you can get it down to the shop we can have a look

[eLtrix]

I took a loot behind the dash this morning. No leaks at all.

[benson]

Could be a air pocket created in the clutch system. Do a simple bleed and see if there's any signs of a air pocket.

[eLtrix]

Gonna do a bleed tommorow hopefully and hope it helps

[eLtrix]

So after some further diagnosis. We have discovered the pedal sinks when you rest your foot on the clutch pedal. We concluded that it might be the CMC leaking internally as it is not able to hold pressure as there were no visible signs of any leaks externally in the engine bay or in the cabin along the firewall.

What do you guys think? Is it possible for the CMC to leak internally randomly like this?

Would it be worthwhile to bleed the clutch as there could be a slim chance of hope it is that (since it will be much easier to do than to swap over a CMC) even though it has been roughly 1-2 months since the last bleed and it was perfectly fine until now?

Regards.

[Batchy]

Here is the operation out of the handbook (manual shop RSX 06)

Operation

When the clutch pedal is pressed, the fluid pressure from the master cylinder moves the one-way valve. The fluid flows through two passages: the orifice part and the filter part. It then
flows out to the slave cylinder to release the pressure plate and clutch disc joint.
When the clutch pedal is released, the fluid pressure from the slave cylinder moves the one-way valve. The one-way valve blocks the filter-part passage and delays the clutch release speed by
returning the fluid to the master cylinder through only the orifice-part passage

So i would be looking at the orifice in the cmc being possibly faulty, if it doesn't seal back up and allow pressure to be held in the line (pushing the clutch up).

You say that when you have your foot on the clutch it will sink, I wonder if turning the corner the clutch pedal is a little loose and applies just enough pressure to make the orifice line to go the opposite way (sinking the clutch pedal).

[eLtrix]

Could very be the orifice part as you mentioned. As even when the clutch pedal sinks the slave is not engaged at all.

Might just replace the whole thing >.>"

[Jongnie]

had this problem before but pedal just sank, replaced slave cylinder

[ZIPPIE Type-S]

If there are no visible signs of hydraulic fluid leaks, it is more than likely a faulty CMC...