Front end noise

[sagebel]

A guy on one of the hunting boards is having a problem and is going to stop by today. Any thoughts:

"I think I have a problem with the hubs or transfer / transmission. It is a 02 4x4. When I leave the driveway, and drive a few hundred yards to the stopsign, as I slow to stop, I can hear and feel something kinda like gears grinding and then a clunk , like something comes out of gear. Then nothing else, drives fine after that.
I am taking it in this week, after newyears. Just wanted to float this out there and see if anyone else has had this. It has the shift on fly, and has hubs that can switch from auto to lock. I recently put a new vaccum pump on it to repair the ac vent issue.
Thanks"


I am thinking a hub issue but I am not ruling out the bearings.

 

[bushpilot]

is this happening in 2wd or 4wd ? does the transfer case switch
from 2wd to 4wd ok ? hubs locking & unlocking ok ?

hub unit bearings ?? brakes ?? (could make a grinding noise, but
wouldnt do it and then STOP).

the following wouldnt necessarily make a grinding noise....
and they wouldnt make a noise and then stop either but are
kinda typical parts that wear out and make popping noises
when turning or hitting bumps (like driveway to street transitions)

ball joints ?? shocks ?? sway bar bushings ??

makes me wonder...if he just had a vac. pump replaced
"for the a/c vent issue" did they have the hubs off ? (did they
get it all back together right ?)

usually if the vents dont work its cause theres a vac. (hub seals) leak.
ask 'em if he was able to lock the hubs and transfer case before
they replaced the vac. motor...were the vents defaulting to defroster ?

the vac. motors do go bad, but its not as common as a hub seal leak.

 

[sagebel]

I also had a bunch of questions for him as well, it is occuring in 2hi. My thought is that the sound is always there but only audible when slowing. Hopefully he will stop by today. He doesn't have a jack to get the front of the truck off of the ground to be able to check everything out.

 

[bushpilot]

obviously in 2wd the transfer case AND the hubs should NOT
be engaged....so makes me wonder where the "grinding noise"
(that stops) is coming from.

perhaps the one or BOTH of the hubs are NOT un-locking...(he could
be the victim of a poor diagnosis of vac. leak someone may have
replaced the pump...taking the quick/easy way out).

1st thing (easiest) id be doing is climbing under it, try to turn the
half-shafts attached to each front wheel (see if the hubs are
locking/unlocking)

a hand vac. pump should show you if hes got a problem at one
or BOTH hub seals.