Ok, first the vitals: '91 Pickup 22re w/161K miles, clutch replaced 3 years ago.

After I shift into a gear at any speed and I rest my foot back on the clutch just a little bit, the clutch pedal will sink back all the way with little or no pressure on it. (I first noticed this in situations where I am stuck in traffic and I have to ride the clutch). With it in this position I can throttle the engine and the truck will continue to speed up, eventually something happens and the clutch will disengage indicated by the engine revving as if in idle. The clutch pedal will eventually come back to it's original position. From time to time it will be difficult to shift into neutral from first gear or reverse with the clutch depressed, I have to let off the pedal and then depress it again to get it out of gear

My thinking is it might have something to do with the slave cylinder? I have done a visual inspection of the master cylinder, line, and slave cylinder but there appears to be no apparent leaks or damage. I believe that is that best that I can describe the trouble, so if anyone has some ideas or help I would appreciate it, thanks!

-Andrew

That's a strange one. I've never heard of a clutch pedal sinking on it's own.

Sounds like a bad spring to me. If I'm right, the most likely culprit would be the pressure plate, but check the external spring(s) first.

Dave

Inspect your clutch bracket too.

Le Linky

Thanks for the ideas guys, I'll check all pedal mechanics under my dash and let you know if I find anything.

UPDATE: I inspected under the dash and didn't find anything obvious. Maybe I just don't know what to look for but I didn't see any cracks in the bracket and as far as I can tell the spring looks fine.

I did some further investigation by laying under the truck while someone stepped on the clutch pedal. When they applied pressure and depressed it all the way I could see the slave piston engage all the way and push the fork. They commented that the clutch provided normal resistance.

But when they barely applied any pressure the pedal would sink back all the way and I would not see the slave engage AT ALL. I'm starting to think it may be a bad spring in the pressure plate as you suggested. This concerns me because I replaced the clutch 3 years ago. I believe it was a daikin from JT Outfitters if my memory serves me. Anyway, any other ideas??

-Andrew

Bad master cylinder.

It's not likely the pressure plate, since neither the slave cylinder or clutch fork are moving, the problem has to be between the slave & the master.

However, I can't figure out how the pedal could sink on it's own against the pedal spring....

Dave

and there is no leaks around the slave cylinder? sounds like it with slight pressure there is a slow leak but when you push it regular it can over come the leak, probably will get worse and you will loose your clutch pedal all together so be carefull.

Second frustrated UPDATE:

So today I tried to leave for class but I couldn't even back out of the driveway. I would put the truck in reverse, but before I could even get give it gas the clutch would start to engage with the pedal depressed, resulting with constant stalling out. I was able to let the truck just roll out into the street but faced the same problem just trying to get out of first gear. I was able to nurse it around the block and back to my driveway. Looked under the hood at the master cylinder and slave and there are still no apparent leaks. I think I'm just gonna have to try and take it somewhere as I don't have the time to do this myself, especially not knowing exactly what the problem is.

-Andrew <img src="/forums/images/graemlins/scared.gif" alt="" />

I had a similar problem in my old FJ55 Landcruiser. Turned out to be an internal leak in either the master or slave cylinder (forget whish it was, shop replaced the bad part). If you sat at a stop light in gear with the clutch depressed, it would slowly start creeping forward as the cylinder leaked down.