LuK slave and master kit installed; and let me tell that pedal is SMOOOOOOOOTH!!! and no more horrendous creaking noise!!!
Now I want to go check mine.My factory system was much smoother and very quiet, but had gotten enough moisture in it that anytime it got really pushed with a heavy load I had to pump the pedal to get it to work. I got sludge out of it several times trying to keep it, even replaced the brake fluid three times with new fluid from containers I had just opened to eliminate contamination. Always better for a short time then it would get hot and quit. First time I took the slave off to bleed it the grey sludge that came out looked like wet cement and a lot of it
My ZF-6 will creak from the slave cylinder. Took me awhile to find it. Only does it when it's warm. Had to have the wife press on the pedal while I was under the truck feeling for it. Been that way for awhile. I have a new pre-bled assembly ready to go in when it dies.
The input shaft on the ZF-6 for the 6.0L has a larger pilot diameter. Some guys running 7.3L's with the ZF-6 have installed that input shaft and bored out the flywheel to match the larger bearing. Probably done by Ford to fix the problem with the needle style bearing. The issue with it is that the flex section in the disk lets the shaft rotate back and forth just a bit with the clutch engaged in relation to the flywheel and put wear spots in the shaft where the needles sit. The cause is the normal diesel engine rotational vibration of the engine crankshaft.I suspect the 6.0 with ZF-6 also uses this bearing but I have never put a clutch in a 6.0 truck. There are so few of them and the only ones I worked on did not need clutches before the owners got out of them.
Do you think if you greased the pushrod that it would prevent the groove from happening?
Jimmy,Sil-Glyde or 3M silicone paste is the slave pushrod grease of choice. I don't know how big a risk but regular grease getting onto the bore of slave (or master too) and getting onto the wall can get to the rubber of the piston and cause it to swell. Silicone sprays are usually 3 drops of silicone and the rest of the can is propellant and inert stuff. SO many of the aerosol lube products will wash away the remainder of what lube paste is there and end up making the problem worse.
Another thing from years of working on these: 7.3 PSD trucks with 6 speeds use that pilot bushing with needle bearing that rides on input shaft. The bearing failure scars the input shaft and a new bearing will fail quickly.
There is a sealed bearing, 6003-crs or 103-cc are some numbers for it in some brands, that fits into flywheel and has an ID for trans shaft that works. if you clean the shaft up. A sealed bearing for pilot is pretty common and I'm surprised they chose the needle bearing which is more problematic on all I have seen it used on. A brass bushing is better than the needle bearing.
The bore of flywheel where the pilot bearing fits is 35mm and the input shaft pilot diameter is 17mm the bearing is 10mm wide but it could be wider if you found the ID/OD the same.. Pilot bearing is not noisy enough to hear it with engine running in many cases. You hve to get truck on an incline, turn off engine, then put it in ger and depress clutch and let it roll. In 1st you will have a high speed at input shaft with rolling speed no faster than a walk. If the growling to squealing noise happens then it narrows it to a small list. Pilot bearing is most likely. A driveshaft support bearing could be noisy but it turns much slower than input shaft in this test. Release bearing (throwout bearing) is not turning when fly wheel isn't turning so that can't be the noise source.
I suspect the 6.0 with ZF-6 also uses this bearing but I have never put a clutch in a 6.0 truck. There are so few of them and the only ones I worked on did not need clutches before the owners got out of them.