Well not too happy about this…picked up my truck last summer from my mechanic. When turning at low speed in the parking lot there was a clucking sound coming from the front end. Thought it could have been my new suspension. We couldn’t figure out what it was so I drove it home 35-40 miles hoping to figure it out in the near future. No light on dash indicating that diff lock was engaged.

The truck has been mostly in my garage since then while I’ve been fixing things here and there. I’ve taken the occasional drive in it and may have racked up 150-200 miles total. No issues when driving and no unusual sounds. Definitely no diff lock light on dash still. Clunking still there when the wheels were turned while maneuvering in parking lots.

I just had it at a different shop for some service (transmission filter/fluid change, transfer case fluid change, and diff fluids changed - told me nothing unusually wrong with fluids or excess metal shavings) this week and they noticed the center diff lock has been engaged this whole time. I’ve never touched it since I got the truck 1.5 years ago. So it was either the previous owner or my other mechanic.

Well there’s no more clunking up front obviously but I’m hearing a rotational clicking noise from the rear when my foot is off the gas and I’m coasting. I feel like I only hear it after the car is warmed up and driven a bit. Granted I’ve only driven it twice yesterday, once back from the shop and then doing an errand later that day.

Am I screwed? Or could it be unrelated? Stuck brake pad? I want to take it back to the shop but I’m not sure if I should drive it or have it towed.

 

the CDL being locked while annoying if the fluid is all good then you should be fine. These are at the age where brake components are going out. I've had a few bum calipers and definitely dead guide pins. Brakes is where I'd start bc they are easy. Do a inspection on the rear drive shaft and grease it, make sure the rubber donut is in good shape.

 

Highway speed shouldn't be too much of a problem; the real issue with the CDL is turning on high-grip surfaces. That can put a lot of strain on the drivetrain because the transfer case doesn't act like a front/rear differential when it's locked.
As said above, check the rear driveshaft and try to isolate the location of any sounds as an indicator of what could be causing the clicking noise.

 

Ok thanks. Hopefully it’s nothing major.

I greased both shafts recently (front shaft is new from lucky 8). The zerk was missing on the rear u-joint and this most recent shop replaced it and greased it for me.

I had the brake pads recently changed but I’ll check the calipers and check for any looseness in the rear driveshaft.

 

I'd check that front shaft too while you're at it...I've had one of those go out on me in under 5k miles.

 

Will do. When I greased it, it seemed tight. I'm a little annoyed to find out that it didn't come greased from Lucky 8. I only noticed that while driving on the highway and hearing a squeaking at 70mph and above. After greasing it though it seems quiet.

Transfer case doesn't make any unusual noises thankfully. My last truck had a whining transfer case which I ended up replacing so I know what that sounds like.

 

I just got a Lucky 8 front shaft and made sure it was greased before installation... My previous one lasted five or six years and I did grease it every oil change... Plan to take it to a drive line shop for an inspection and rebuild for use as a spare. Then I will know what failed but it looks and feels tight when not under load. I suspect the center ball but have no idea yet. At first I thought I had an idler or tensioner going bad... then it got all metallic sounding and I stopped driving it and ordered a replacement. All noises now gone and it runs smoothly.

Regarding calipers, YES, pull the guide pins and do a thorough cleaning of the pins and the tubes then relube. It will most likely need it.

 

Going to drive by my shop in a little bit and have them take a quick look. Since they have a lift, it might be easier to inspect some things rather than me on my back under the car in the garage.

 

Just got back from my shop. Confirmed it was just the brake pads moving around (it's a rhythmic knocking sound). Sound stops as I lightly depress brake pedal. Also did a test where I depressed brake pedal with light acceleration and noise wasn't there. Glad it's not driveline related.

I guess I'll get under the truck when I have time and make sure everything is tight. I've got the Akebono EUR493s in the rear.

Back to the Center Diff Lock, is it common for the dash light to not come on?

 

it is not. usually means the switch that tells the light to turn on and off is bad or unplugged.

had the same thing happen on one of my '04's.