New to the forum, not to cars. Have been a mechanic for decades (both street and track) but have always deferred my diesels to a shop as they were older tow rigs.

However, I now have an '03 F250 Super Duty as my DD. I recently acquired the truck and it is a good solid beast with 260k on the clock, however at the first opportunity to test the 4WD when we had
snow, there is a soft grind/ clunk in the drivers side front. After reading a few threads I performed the following tests with the listed results:
2WD hubs disengaged (normal driving) = no noise
2WD hubs engaged = no noise
4WD HI engaged, hubs not engaged = no noise
4WD LO engaged, hubs not engaged = no noise
4WD HI & LO with hubs engaged = noise.

From everything I have read, this points to a bad u-joint.
Unfortunately, I am recovering from a complete anterior hip replacement less than 6 months ago, so pulling an axle and swapping right now really isn't in the cards for me.
Long story short: A reputable shop that I often refer people to took a look at it this morning. Their first call to me said there was no problem, I asked to have another mechanic test it. A little later, they called back and said another mechanic test drove the truck and thinks it's the transfer case. When I asked them if I could stop by and check it out on the lift with them to pinpoint where the noise was coming from, they claimed their lift wasn't big enough for the Crew-cab, 8ft bed truck. I'm going to pick the truck up later this evening, but to me sounds like they just don't want to even work on it..
Am I lying to myself that this is just a u-joint problem??
Anyone ever been able to R&R that u-joint without removing the hub, driveshaft, etc??
Any possibility this is just a low fluid level issue? I 'may' be able to slide under and check/fill without too much hip-difficulty.

TIA,
Nick

1999 E350 Dually Cutaway 7.3 400,000+ mi
2003 F250 SD Bulletproofed 6.0, EGR delete, Manual transfer case & manual hubs

 

Welcome to the FTE community Nick. I am definitely not a mechanic but it seems to me by your testing protocol, if it only happens when the hubs are engaged ... it likely could be the u-joint at the wheel. I had both of mine replaced and you could tell they were worn by the fact there was play in them when you put your hand on them and yanked them around (only a little play mind you). Also, my truck was on a hoist so there was no weight on the wheels when my guy demonstrated the wiggled in the component. On it being the transfer case, it seems our trucks are pretty solid and the only threads I recall seeing is where the TC has "grenaded".

I'm sure some of the folks with WAY MORE expertise will spot this thread and chime in with their thoughts.

 

Could be a bad locking hub not engaging all the way and you are hearing the gears rubbing each other. Mine was doing that, but it was the drivers side not fully dis-engaging. The gears were just barely rubbing against each other, with an occasional clunk when I would get slow enough for the gears to try to engage every now and then.

 

^ Now that is a distinct possibility! I had wondered that since it almost has a "purr" of splines not engaging. I'll see how long I can crouch & try and pull that tonight and see what the inside of the hub looks like. Thanks!

 

While it is making the noise does 4x4 work? If so I would doubt it being the hub, since if both sides are not locked in neither front tire will have power going to it. Only the back wheels will spin, unless it is half engaged.. not certain though. Are the dials turned all the way? I had one freeze up before and couldn't get it to turn the last 1/4"

Does it sound like a chain slipping on a motorcycle or dirt bike? That could be the transfer case chain.

 

Takes less time to pull the hub , than drink a beer .

 

I'm either a better drinker or worse mechanic than you😂

Kidding aside, it does only take a few minutes if you have done it before

 

Easy to see if the ujoint is bad. Jack up the wheel lock the hub truck in 2wd turn wheel all the way to the right. grab the wheel and turn around if the joint is bad it will bind bad going around or you wont be able to turn it.

 

If they mechanic can't get it up on a lift, get the creeper out and slide underneath it. It isn't that hard to troubleshoot. I would first check the u-joints. There are u-joints on each end of the drive shaft and a set on each side heading out to the hubs. If they are okay, then the hubs. With 16 years of use and 260,000 miles on it. It wouldn't be a bad idea to put a new set of u-joints in. Also, service the hubs.

I really doubt it is the transfer case. It sounds like your reputable mechanic didn't do proper diagnostics and would rather throw parts at the problem instead of following the process.

 

I'm assuming that's the auto-locking hub. All it takes is a regular set of needle-nose pliers and some patience (and maybe a small wood/sand mallet). Plenty of YouTube videos on that. Getting it back on is the hard part. It might line up right the first time or it might line up right on the 50th time.

I agree on the second opinion. From what has been described it sounds like something in the front driveline area. Pulling the wheel hub and axle in the front is not a difficult job, just time consuming. Unless the shop isn't confident on what the problem is or really doesn't have the lift capabilities, I don't know why they wouldn't want to do the job.

To test the transfer case possibility you can manually lock the hubs and stay in 2WD to see if the noise is there. It will spin the axles but not load down the transfer case. While stuff is still spinning in the transfer case it will not be engaged and unloaded. It's free and if nothing else adds to the troubleshooting.

16 years is beyond a good life for those u-joints. If you do have the axle pulled, I'd recommend replacing the u-joint whether it is the problem or not as 1979 Ford said.

Just my .02