My clutch pedal started acting weird today. I have a 2004 six speed. I went to press the pedal and it went straight to the floor, and didn't come back up. The clutch isn't opening. I also had a few random dash lights go off (windshield washer fluid level, seat belt indicator). The issue went away after a few minutes. The fact that it isn't constant and the symptom correlates with the dash indicators makes me suspect an electrical issue somewhere. Has anyone experienced this before?

My first thought was the clutch master cylinder but the electrical symptoms make me think not.

 

This is just a wild thought but have you checked the fluid level in the master cylinder?
There might be air in the system, that does not explain the
Lights but .........

 

Thanks. I'll check the fluid before probing electrical. I'm going on a week long trip so it will take me a while to get to work diagnosing the issue. I'll update the thread in about 1-2 weeks when I get time to work on it again.

 

The bizarre electrical seems to correlate with clutch issues but my repair manuals do not indicate any electrical diagnostics when servicing the clutch system. Looks like I will have to try bleeding out the system when I get some time to do so. Hopefully its just some air in the hydraulic fluid.

 

If the level is dropping I'd look for fluid at the slave or at the clutch rod opening under the dash. If not dropping it is most likely the master cyl piston seal not holding pressure all of the time.

Just probabilities to check, not certainties.

 

`Master cylinder piston' should more accurately read`clutch master cylinder piston'.

 

The master cylinder fluid level was full. Yesterday I replaced the fluid in the master cylinder and flushed the hydraulic system at the clutch and the four brake calipers. The previous owner said he had a brake job which included bleeding the brakes, which would have been about 10k-15k miles ago.

The rubber dirt cover over the clutch bleed screw was a little wet with what I assume to be brake fluid. The fluid that we bled out was pretty dark and looked like it had never been changed.

The front calipers had some brownish fluid. The rear calipers had a pretty clear fluid. Overall it looks like the brake system had been flushed out.

The clutch works now. I will monitor the clutch bleeder to see if it continues to leak.

I looked under the dash panel to see if I could find the clutch master cylinder without having to remove the underside trim panel. I could not see the clutch master cylinder with the trim still attached, BUT I can see some sort of liquid on the boot that goes from the brake pedal through the firewall. I assume this may be brake fluid leaking gradually from the clutch master cylinder.

The leak is really close to the brake light switch and I have had intermittent issues with my brake light function. I am suspecting that brake fluid has been leaking onto the brake light switch and causing electrical issues.

Since this car is like a christmas tree (one light goes out and the whole thing goes out) I believe my odd electrical issues may be coming from the leaky fluid. I will inspect under the dash and either update this thread, or make a new one for the dash lights.

 

So yesterday I finally got under the driver's side dash panel and inspected the master cylinder piston. It appears to be dry and functioning. The clutch pedal generally has good pressure but it did go soft one day about a month ago.

I suspect the slave cylinder may be leaking. I did find hydraulic fluid in the dust cover at the bleeder when I bled it out a few months back. Its not leaking much because the fluid level in the master cylinder is fine. There must be just a little bit of air getting in the line.

Whenever I get around to inspecting the slave cylinder I'll post another update.

 

It is possible that fluid is leaking by the piston seal it will not necessarily leak out, it just gets behind the seal and gets made up when the piston returns to its original position and oil passes through the seal gap. The seal may do this off and on depending on the seal damage. Crap getting under the seal would do this.
I'd guess you need a new cylinder assembly.

 

I assume there's not a good test to see if it's the master cylinder piston vs the slave cylinder at the clutch.

The only symptom that leads me to the slave cylinder is the fluid I found inside the dust cover when I went to bleed the clutch hydraulics. I didn't find any fluid at the master cylinder when I pulled the dash.