Weird groan leaving a stop.

[BR3W CITY]

My 05 Yukon has a weird little issue, that I'm not even sure is an "issue" as much as I just don't know what its doing.

When leaving from a stop or low speed accel, I get a "groan" until I get to around 9-15mph. Its not everytime, and it doesn't seem to react to particular conditions.

It sounds a bit like a power steering groan, but it feels like its coming from a bit further "back" than a PS issue usually would, and it doesn't react to steering input from what I can tell.

Any thoughts? Possibly something in the transfer case or 4wd system?
Its snowing AF out today so I'm planning on playing with the 4wd a bit to see if being in Auto, 4l or 4H makes a difference.

[99LS1500]

Have you checked your PS Fluid level lately ?
Is it clean and at the correct level ?
Check to see if your rack & pinion is leaking. It whines / groans just the power steering would if the PS Fluid is low. Fill the PS Fluid to the correct level and if the whine / groan stop you found your cause.

[BR3W CITY]

PS looks fine, and I've never seen a leak from it. I'm going to drain and change it for fresh stuff.

Semi related, I'm confident its time for a new alternator as well. Its the factory unit with 130k on it, and the brushed aren't putting out reliable juice anymore (seen it on many higher mileage LS's). From what I can tell the alt isn't the groan source tho.

[izzy_Britton]

my truck started making a funky new noise last night after work while letting it warm up before hitting the road... as with most cars for the past 20+ years, when my defroster is ON the AC pump is pumping. something i never understood but, i noticed last night that my AC pumps constantly, not on again off again like in the old days.

possible if you dont figure out the source of your noise, remove the AC belt and see what that gets ya?

Izzy

[dennislbrooks]

Probably not your prob but I had a 2004 Yukon --it was a good horse -- but the muffler shroud did break loose--vibrate-- and would make an annoying sound on start up and when starting a load. I used some stainless spinning wire to tie it back down to the muffler. It had 140K on it.

[izzy_Britton]

Originally Posted by dennislbrooks

Probably not your prob but I had a 2004 Yukon --it was a good horse -- but the muffler shroud did break loose--vibrate-- and would make an annoying sound on start up and when starting a load. I used some stainless spinning wire to tie it back down to the muffler. It had 140K on it.

my daily driver SHOP TRUCK has this going on now, but it is an obviously tinny noise...

[BR3W CITY]

Originally Posted by izzy_Britton

when my defroster is ON the AC pump is pumping. something i never understood

A/c turns on with defrost because of cars that exist in northern climates. Manufacturers didn't use to do that, but too many A/c pumps would seize the clutches from lack of use. They decided the easiest way was to add a clutch trigger from the defrost switch as well so it would run in winter as well.