You should only lock the transfer case if you are driving on low-traction surfaces, or if you remove one of the driveshafts. Removing a driveshaft without locking the transfer case will render the vehicle immobile.
I think that locking is being suggested as a way to remove each driveshaft in turn in order to eliminate (or identify) one of them as the source of the noise.

 

Once again, it is a very good idea to fully remove the front driveshaft every oil change and inspect all the joints and grease them fully. A catastrophic drive shaft failure can be very expensive. It can also be removed and the truck driven with the tcase diff locked to see if it is the source of a driveline noise. That said, the typical driveshaft noise is best described as a chirping sound at walking to jogging speed.

 

OK, just to be clear. I’ve read that the center locking differential should, in general, only be engaged when driving on low traction surfaces. However, it sounds like you both are saying that if the front driveshaft is removed, it is OK to lock the center differential and drive over normal paved road. Is this correct? Is it also safe to do this at relatively high speed, say 60 mph? As noted in the OP, there really is no noise below 45 mph, so I would need to be going pretty fast to do this test with the front driveshaft removed.

Again, thanks to everyone for their input.

 

Yes, it is safe to do what you are proposing. However with no noise under 60 it is highly unlikely it is the front driveshaft.

 

Ok, thank you. Just to be clear: no noise under 45, then increasingly loud rumble as speed increases over 45.

Side question: I saw on your website that on at least one of your vehicles (in blue) you painted just the hood and the top, with the top done in white. It’s really attractive, and I’m considering the same for my crimson Disco. Can you recommend a specific paint facility for the job? I’m in Alabama, but I don’t mind driving for high quality work.

And btw: like everyone else, the inline thermostat is working out great, with consistently much lower engine coolant temps.

 

Yes, there is a way to easily manually do it with a 10mm open end crescent wrench. It's a bit of a fiddle, and you can burn yourself on the exhaust if you do it when the car is hot - but search on here, it just 'clicks' over 90 degrees which locks the CDL (center diff lock). The light on your dash will even come on! Only do this with the front drive shaft removed.

 

Ok, thank you. I take it that this is the bolt/switch located on top of the transfer case?

 

Yes. from inside the car with the center console removed it should look like this. While you won't be able to see it from underneath hopefully this will give you insight on the shape and location in reference to the front driveshaft. Note the shape of the stud/nut whatever the name of it is. It can be turned by a 10mm wrench if I remember correctly. Hopefully there isn't as much grease and gunk as there is on mine.

 

Sounds like a wheel hub bearing going out, try to see if it is louder turning and then notice right vs left. BTW, still a good idea to check the front driveshaft. Wheel hubs usually start going out with a low grade roar that gets louder as they wear but you would really have to ignore it a long time for it to fail catastrophically.

I actually plasti-dipped the roof myself because I had mixed reviews on the white roof and I wanted the buyer to be able to undo it if they wanted. The buyer loved it, so he has not changed it but will have to redo it in a few years (too tall to go in the garage so exposed to the sun all the time). I have a local painter I use - suggest going to your local car show/cruise ins and ask around about the best local doing side work. Car show guys are usually pretty picky about paint.

 

[QUOTE=Extinct;913646]Sounds like a wheel hub bearing going out, try to see if it is louder turning and then notice right vs left. BTW, still a good idea to check the front driveshaft. Wheel hubs usually start going out with a low grade roar that gets louder as they wear but you would really have to ignore it a long time for it to fail catastrophically.

I will check that. I’ve replaced a couple of hubs previously. But we did check for movement a couple of months ago, and everything was solid. Maybe I drove over something.