91 F-250, 4.9L 5sp OD Tranmission. Rough Farm Use history. Lots of new parts installed in our farm shop. All working fine and shifting smoothly, Trouble started while pulling 3000 lbs of seed on a trailer, attempted gear shift and clutch slammed to floor and stuck. The clutch pedal was frozen, platic retainer clip broken and Master cylinder push rod would not move ?

Slave cylinder had leaked - could see oil outside of tranmission. So the boys pulled back the tranny and installed a new one. Pre Bled with new throw out bearing. - Did not fix


Master cylinder then, so went to town and after three tries found the part matched from a 1990 F200 Mexican model??? Whatever that means!
Installed the master cylinder, opened the bleeder, let it gravity feed. After 3 -5 stokes the clutch pedal did the same thing - Cannot push the clutch pedal in at all. It appears that after both the master and slave cylinder have been replaced that we are back to square one. Clutch pedal cannot be depressed - pressure in line. Transmission shifts fine when truck is not running.

Any thoughts please

 

I'd say the Pressure Plate fingers are jammed by something. Either the Pressure Plate is bad or the Clutch Disk is bad.

When you push in the clutch pedal the Slave Cylinder is trying to push in the Pressure Plate fingers. Since the fingers on the Pressure Plate can't move somethings got to give. In your case the Slave Cylinder blew.

 

If the slave cylinder is allowed to fully extend, it'll do exactly what you're describing. The boys should have looked at the pressure plate while they had it apart. I think you'll find bent, broken, or collapsed pressure plate fingers that are allowing the slave cylinder to fully extend. The original one probably leaked because it was extended farther than ever before, and the seals didn't seal well against the old, corroded metal.

 

Thanks for the information. That makes good sense! Back under the 3/4 ton one more time. I am sure that the boys will be more than thrilled to pull that tranny again. Two or three of us can make quick work of that one now.

Its a good thing labor around here is fairly cheap. Replaced the tranny and mounts, motor mounts, ingition system and starter, lock outs, etc etc over the last year. Maybe this fix will be the charm. Need to get some more use out of now so I can at least get some parts money back.

The boy's, one of my sons and a couple of his friends, ages 18 to 21, have tackled of all sorts of pickups and cars these past 4 years. I trade them their labor to keep my stuff going and in turn they get to use my their tools in my shop to work on their own stuff. Worked well for all parties involved.