'02 F350, 4x4, manual trans and manual xfer case w/ lockouts. Problem no. 1: with the hubs locked, in 2-hi, real sharp turns will produce a clicking sound. With 4x4 engaged, I hear a rumbling sound straight or turning. Sound goes away when shifting back into 2-hi. I think this indicates that the front axle u-joints are bad.

Problem no. 2: push in clutch to put in gear, and let out clutch, I hear a rumbling sound. Kinda sounds like something is loose. Clutch doesn't slip and gears engage fine. I think this indicates a bad throw-out bearing, or damaged clutch disc springs.

If the front axle u-joints are bad, I'd like to replace that first since it impacts the 4x4 operation.

I think I'd wait until the clutch/t.o. bearing problem gets worse. Any potential problems with that, e.g., damage to the tranny input shaft, bearings, etc?

Any thoughts? Thanks!

 

Bump, bump, bump.

 

Could be. Could also be driveshaft, transfer case, or front axle problems. You'll have to get under there and look. For the axle u-joints, turn the steering wheel full left or right then jack up the front end. Lock one hub and spin the wheel on that side. A bad u-joint will be evident by binding or noise.

I'm a little confused as to whether the sound happens while the clutch is engaged or disengaged. If the sound happens with the pedal up, it is probably the input shaft, input shaft bearings, or countershaft in the trans.

If it happens with the pedal down, it could be the pilot bearing or throwout bearing.

That's fine, but if the trans goes then it won't matter if you have 4wd. If the throwout bearing is bad, it may slowly grind itself to pieces over the course of thousands of miles. Or, it could decide to just come apart and you'll be left without a clutch. It may or may not damage the pressure plate.

Since we can't experience the problems you're experiencing, if you're not sure how to go about repairing it you may want to have a trans shop give you a diagnosis. They may be able to give you a better idea how serious the problem is.

Jay

 

Problem #1 sounds fairly normal. You will get more driveline noise when in 4 wheel drive. A full lock turn left or right while the front hubs are locked will result in a little binding with some noises also. It would not hurt to take an hour, pull your hubs, clean them and grease them very lightly and inspect them.

 

I don't think the noise I'm hearing in Problem no. 1 is normal. I've had lots of 4x4s before that didn't make this much noise in 4wd. I do intend to inspect the front hubs per your suggestion, but I'm thinking it's front axle u-joints or possibly the transfer case.

I did change all the drivetrain fluids when I bought the truck and didn't see any metallic pieces in the fluids. The front Dana 60 is pretty stout and the gears looked ok, so I think the actual diff set is ok. I think the BW transfer case is pretty durable, but I suspose there could be problems with the bearings.

Now that I'm thinking about it, since the rumbling only occurs when the transfer case is shifted into 4wd, it may well be the transfer case. With the hubs locked and the case in 2wd, the front axles and front driveshaft are turning but no rumbling. When shifted into 4wd, power is transferred through the appropriate transfer case gears and bearings to the frt diff.

I was aware of potential problems when I bought the truck, but it was a good deal, and a configuration I wanted.

Thanks for the suggestions. Keep 'em coming!