Noise when in Auto or 4W high

[2018TahoeRST]

I have a four wheel drive 2018 Tahoe with the 6.2L. I often drive in "auto" and yes I know that is not recommended. Maybe my tires are shit but if I don't my ass end slides on left hand turns. Anyway I get a loud humming (whirling) noise when I am in "auto" or 4 wheel when I hit the gas. When I take my foot off the accelerator the sound stops. The car has 70k miles and has never made this noise before. I take it to the dealer and the guy just goes "well put it in 2 wheel - problem solved". I slide all over the place in 2 wheel and even the steering seems looser (if that's a word). I figured I would turn to the forums as you guys always seem to know about issues like this. Has anyone experienced anything like this before?

 

[Blackcar]

I'm sure you have bought new tires at some time and if you have, they do anything to change in the way vehicle drives in 2WD. I don't have as many miles on mine and still have same tires which aren't great in stability, but they are getting worn.

 

[Patten]

Mine used to have a whirring sound caused by a loose fit of the front axle and going into the t case. Parts were worn. Seems that is coming back around too even after a t case rebuild.

 

[B-train]

All my vehicles that had the AUTO selection over the years made a little more noise when selected. You're activating the front axle and relying on a clutch in the t-case to engage the front axle when slippage is noticed from the rear wheels. You're going to have more noise, there are more parts moving.

There is one caveat though: if your tires are not a matched set and/or worn like you do burnouts with the rear and the fronts are new, you can end up with driveline binding issues. It will be very noticeable on hard surfaces, not noticeable on slippery ones. 2 sets of tires fighting each other will result in more driveline noise.

Also, I agree with not using AUTO all the time. Just ends up giving you less mpg and more internal wear. That being said, I would highly recommend changing the t-case and front dif fluid if you haven't already.

 

[lbenson]

I've been told driving in Auto on dry pavement will slowly destroy the 4WD system. I always avoid it and only use Auto in snow, and Auto 4WD is only to be used at 55mph and less (been told by GM Mechanics). Not sure why you're sliding all over the place in 2WD - could be the tires on the truck. I never have traction issues in 2WD with Michelin Defenders, not even in rain.

 

[B-train]

Maybe his right foot is made of lead.....LOL. I drive a 2017 with the 6.2L and it will DEFINITELY get squirrelly when the GO pedal is tromped on. However, the stabilitrac keeps the fun to a minimum for sure.......even when I turn it off. Almost impossible to get sideways with it on.

 

[sealandsky]

Hi - I'd start with new tires. I'm running Michelin Premier LTX and have zero issues with the truck getting loose unless I try (and I usually drive with the traction control off). Additionally, my Yukon has the Callaway 560 HP option. It sounds to me that the "auto" clutches are getting worn out and there could be a new transfer case in your future.

 

[RLC2020]

Running in 4wd is not a fix for having crappy tires. There is ZERO reason to drive in 4wd or auto 4wd on dry pavement. Get new tires or stop flooring it in turns. My truck is only ever in 4wd at the boat ramp or when I am off road and actually need it. You're burning up your driveline for zero reason.

 

[shekmark]

Is the four wheel drive system different in an 18 . All the ones I’ve had from GM, while in four Auto, they are two wheel drive and the front only activates if slip is detected. It was perfectly fine to drive in “ ato” all the time. Four high is a different story and you would not use that except in loose or very slippery conditions.

 

[mb1500]

Is the four wheel drive system different in an 18 . All the ones I’ve had from GM, while in four Auto, they are two wheel drive and the front only activates if slip is detected. It was perfectly fine to drive in “ ato” all the time. Four high is a different story and you would not use that except in loose or very slippery conditions.

You are correct. The front axle is engaged and the TC clutch is minimally engaged during AUTO. Will have some additional wear driving around in auto all the time but is within the parameters the system was designed for.

If OP has been letting the 6.2 eat in auto for 70k than he might need to have the TC looked at maybe some new fluid:

https://static.nhtsa.gov/odi/tsbs/2019/MC-10163252-9999.pdf