I was rolling downhill and I shut the truck off and coasted a bit in neutral and about 1/4 mile downhill the front end started to make a grinding sound. I quickly started the truck back up and it went away. Any reason why something would grind with out engine power?

I don't plan to do that again for testing but it would be nice know what it is in case it ever dies.

 

coulda been the breaks. don't they run on vacume. I'd just throw it in neutral and leave the engine on if your gonna do it that way and try to pinch gas. I've done it before trying to save gas till I could find the next station

 

probably front hubs trying to engage, not sure though.

 

ur hub vac solenoid is ran off the ignition, go under the hood and have someone switch the ignition on it is audible on the pass side towards the firewall. The front hubs are engaged with the ignition not in the "on/start" position. Be careful I'm not sure if that can damage ur hubs or not but the hubs are not what I'd call reliable I believe one of mine is shot but I'll find out when I fix the tcase.

 

boy am I glad I have one of those 2wd thingies

 

Josiah is correct. When you shut off the engine the vacuum went away allowing the hubs to engage. This alone shouldn't have made any noise but my guess is this was from the transfer case. Since you weren't turning the shift **** to 4x4 setting the front driveshaft was trying to engage the transfer case while it was still in 4X2.

 

I was thinking it might be those hubs as well. Thanks all!

 

its from the hubs, there is a service message about this. but its not while coasting, its during normal driving and the hubs partialy engage. it has to due with the solenoid being faulty.

 

This reminds me of a little story.. Back when I had my 2005 GTO I was goin’ around 35mph and pulled the parking break to try a little rear slide. But instead of lockin’ up the rear tires, it made loud popping sounds kinda like a machine gun goin‘ off!! Freaked me out, but now I know not to use a parking break as an emergency break! Still don’t know what happened. Just learned not to do it again!!

 

Josiah, is right it is due to you not having vacum on the solenoid. Don't worry you probably didn't hurt a thing. Mine, errr I mean I have heard people with solenoid problems have had there hubs grind at 80mph for a hour or two. (not recomended, but was on a push)