For about 2 weeks I noticed my clutch pedal losing range of motion and being closer to the floor at full engagement. Until one day the engagement point was below the floor, and I couldn't disengage the clutch. I bled the system, added new fluid, and the problem was fixed for about 500 miles of driving. Then after sitting for a day I got in it and noticed the clutch was getting closer to the floor again. This time the range of motion deteriorated while driving, and I was stuck in the road unable to disengage the clutch or shift gears. I once again bled the system, at this point the system is full of fresh dot 3. The problem is fixed again, and again fails a couple miles into driving.

My best guess is there is a leak somewhere that's letting air in. The reservoir doesn't appear to being dropping in level much at all, but the pedal is actively losing effectiveness. How would I even go about diagnosing the location of such a leak? How much do you think a mechanic might charge?

Is 2003 ford ranger 2.3L 4X2 manual.

 

If you're not losing fluid, my guess is the clutch master cylinder is failing internally and needs replaced.

 

+1 ^^^^

If you feel comfortable in changing the Master/reservoir/hose as a unit, then I would do that work, as it can be done without removing transmission, its not too expensive or mechanically challenging
Mechanic should charge about 2 hours for this, + parts, doesn't take 2 hours, but it is usually just minimum shop charge

If it doesn't solve the problem then transmission will need to be removed to install a new slave
Pulling and reinstalling transmission is about 4-5 hours + parts and if clutch is more than 5 years old just replace it

 

Yeah, the master is not terribly difficult to replace. Probably the 3 hardest parts of the install will be

Removing the splash shield from the driver wheel well (required)
Removing the neutral safety switch from the master cyl rod
Disconnecting the quick-disconnect that attaches the master cyl/hose to the slave.

You will also want to make sure you bench bleed the master, or you will have to bleed it on the truck, with the master not installed. For further info, click the link in my signature.