I hopped in my truck today and went into reverse just fine, the when I pushed the clutch in it did not disengage. Finally got it out of gear after killing it, then tried to put it in 2nd and no such luck. The pedal has pressure at first, then it goes away and I get a dead pedal. I have heard the slave cylinders on these trucks are junk to begin with. Sounds much like the slave cylinder, but I talked to a diesel tech and he said it might be the master cylinder..Anyone ever had this problem before??

 

It's certainly not the master cylinder for the brakes.

There is only one hydraulic cylinder for the clutch system, so I suppose it is the "master" slave cylinder. Yes, they are junk. Yes, they are on back order.

 

My 03 3500 4X4 6 speed Ram just started doing the exact same thing. There does not seem to be any rhyme or reason to when the clutch fades away but usually after it is warmed up and in the lower gears like 1st and reverse. I could be sitting at a light with the truck in gear and my foot on the clutch, and all of a sudden it will start to engage as though I was releasing the clutch but I actually have the clutch pedal to the floor the whole time. If I double pump the clutch she comes back fine, other than that I need to shut it down to get it out of gear. And the clutch integrity feels strong, no slippage at all.

I have one shop trying to tell me it may be the throw bearing being dry and sticking. They are figuring this because the truck sat for a month and a half while I was working out of town. I'm having a hard time believing this though, it really feels like air or something is slowly leaking into the system and the clutch gradually engages while the pedal has been held to the floor. But I am no pro so I'll take any advise that sounds solid. All the dealers that I seem to call do not know anything about it.

 

Check the fluid in the reservoir (driver's side, back of engine compartment, has a yellow cap I think). You can also usually see it leaking (couple drips on driveway that are not from the breather tube (which the 6.7's don't have, but your 5.9l does). Could also be wet around the where the clutch hydraulics attach to the trans. Get under there and look real good with a flashlight. Maybe brake clean it and look after a short drive. I once had to drive one 120 miles without a clutch. I'd be gettin it looked at by a reputable mechanic.