I was down with an illness and my 4Runner sat for a month. When I finally got back in it I noticed that the clutch pedal now seems to have virtually no resistance in its travel. The clutch still disengages but it engages very late in its up travel.

This is new - it didn't use to feel like this.

Clutch master cylinder is 6 mos old and new Aisin. Fluid is full and there are no leaks anywhere in the system. Slave age is unknown.

Thoughts on how to troubleshoot or diagnose?

 

Usually clutch MC and slave cyl should be replaced as a pair since they not get worn on their diaphragms. I would try that first.

 

Thanks! I ordered an Aisin slave from Amazon last night. Arrives Tuesday.

 

you mean that it engages up near it's normal resting position, when your foot isn't on it? that is an adjustable parameter.

clutches usually fail in the opposite direction, in other words they engage too close to the floor.

have you looked under the dash? i think that there is a helper spring attached to the clutch pedal, that could have an effect on pedal resistance.

 

Yes, you are correct. It's engaging very close to the full rest position.

The helper spring is there, I replaced it a while back when I did the clutch master cylinder. The pedal return action is fine -- this feels more like loss of hydraulic resistance.

I'll provide an update once I get the slave installed tomorrow.

 

Slave cylinder fixed it. The old one looks original - 323k miles.

Thanks for your help!