This is not the rear end "thump, bump, or clunk", because I've got that too. What this is is a slight bump from the front end of the truck soon after take off when it is parked for a while. It's subtle, but it's enough to hear it and feel it in the pedals. In fact, the bump occurs a second after the doors auto lock. I've disabled the door locks to see if that was it with no change. Truck turns and handles fine, with no other sound if going over speed humps or anything similar. The only other issue I could see being related is with the front hubs, and that's only because I've had issues with the 4wd engaging or disengaging well. I usually have to rock the truck some to get it out. Otherwise, it sits there revving up with the speedometer creeping up. I place it back in neutral until I can get it rolling enough to engage in 2wd.

 

it would make sense that it's related to the IWEs or the vacuum lines, solenoids, or check valves related to them if you have issues engaging and disengaging 4wd... when you shut off your truck the iwe's would lose vacuum until they were engaged and when you start back up the truck they should be pulled back.

 

School me, please. What are IWEs?

 

IWE = integrated wheel End which are where your cv axles attach to your hub.

its in place of manual lock out hubs so your wheels free spin when not in 4wd. they are disengaged by vacuum so when your truck is not running they engage even though you are in 2wd and your transfer case is disengaged. if you are having trouble shifting in and out of 4wd, it would either be at the IWE's or the transfer case. if this sound is related to your 4wd engagement/disengagement issues, to me it would make sense that it's at the IWE's since they are being engaged and disengaged everytime to start and turn off your truck in 2wd,

 

find anything Fireman? Have you checked the sounds while on dirt and in 4wd?

 

I haven't checked either way yet. I will do it this weekend.

 

Well, knock is still there. I've just dealt with it, but it's about to head to the shop. It seems to get more obvious, where before it was subtle. It won't do it in 4WD, which makes me lean towards to IWE. I suppose this is something that needs to be replaced, and not something that I can try to resolve myself. I have a few other items that the dealership needs to address anyways, but I wanted to check back in here and see if anyone else had any ideas.

 

Sounds like the driveshaft slip bump that gets talked about around here so much.

 

See original post. I have that bump as well; this one is different, and I am having a hard time describing it. It's a dull knock/bump/hit of some kind that only occurs after I have it parked for a while, then drive forward. It feels like a valve is settling in place when I get going a certain speed, but it doesn't keep doing it. I can't remember if I mentioned it before, but it won't do it when I put it in 4WD, but once I take it out it will. I'm fairly certain it's the IWE the more I think about it. I just wanted to check and make sure it couldn't be anything else, because it doesn't have a rattle or grinding sound to it like the IWEs can get when they go bad.