Strange clutch behavior (2002 Accord)
 

Hello folks...

Here's my dilemma

2002 Accord 4-dr EX-L 4-cyl 5pd

When the car has been sitting overnight, the clutch pedal is really hard to press and also feels springy/spongy all the way to the floor, rather than having the normal feel of firmness up until the midpoint an then more free movement to the floor.

I have checked the master and slave cylinders and there are no leaks outside or on bell housing nor on the floorpan/under carpet.

The problem goes away after some driving and then returns after the car has been sitting again. So it seems to be related to fluid temperature.

I know it could be the master/slave clutch cylinders, but I'm trying to understand also (as part of having a definitive diagnosis) as to HOW the symptoms I have could be caused by one/both cylinders being bad?

My theory is that when the fluid gets hotter, the seals in the master cylinder are expanding just enough to seal properly and this is why the behavior changes after a bit of driving.

However I still don't understand why the pedal pressure is increasing under cold starts though...if fluid was leaking past the seal, I would expect the pedal to feel soft.

Thanks for any thoughts/theories/discussion/diagnosis.

Cheers.

It definitely sounds like a problem internally with the master or the slave.

The spongy feeling is from the brake fluid getting past the seals. When I bled my system of air, the pedal felt stiff to me.

A sticking slave cylinder can cause this pedal feeling too.

I would suggest replacing them as a set.

The only other item that would cause a problem is the clutch fork sticking. But that wouldn't give you the spongy feeling in the pedal.

PAhonda - Thank you for your response. Here are some more notes from what I have noticed since I posted:

Yesterday, after the car had been sitting all day, I had someone press the clutch in for me and opened the master cylinder and looked to see if saw any bubbles, or any fluid working it's way back up into the cylinder and didn't notice anything.

I also had them hold the clutch in and watched the slave arm and it protruded as the clutch was pressed and didn't return back (i.e. to check for some leak around seals)...

Since pedal travel seems to be affected (pedal is lower to start with) (I really only noticed this today for the first time), I think there is definitely some hydraulic issue at play here.

The car has 170k on it - I've had it for the last 50k and I don't know if anyone changed the master/slave cylinders yet - so I think it's probably a good place to start. I'll report back with results once I have done the work (probably a few weeks away on my list of things to do and I have an alternate vehicle I can drive in the interim).