[NickTransmissions]

My 2017 Chevrolet Silverado 1500 LT with the 6spd is making an odd whirring noise when accelerating from a stop through 1st and 2nd. The truck is almost at 103,000 miles. The issue only happens when in drive and doesn't seem to be wheel bearing or accessory drive related, so I am starting to narrow it down to the drivetrain. It also will occasionally happen with moderate to hard acceleration, such as getting onto the interstate. With as many miles that are on the truck, I am worried it may be torque converter issue. If it is the torque converter, I hope it's possible to catch it before it takes out my transmission, $600 vs $6000 is a big difference. Has anyone experienced this issue before?

Literally tons of people have experienced this with that transmission...It's likely the converter but could also be among the following:

1. Front planet/sun gear/ring gear starting to break up - if it fails completely you lose all forward and reverse movement
1B. Rear planetary carrier / ring gear(s) or sun gear(s) failure

2. One of the hubs (1-2-3-4, 3-5-R or 4-5-6) - the 4-5-6 hub is the most vulnerable in the transmission and common practice is to replace it with a Sonnax billet hub (36 or 45 lugs on the hub)-45 lugged versions allow for Powerglide frictions to be used)

3. Torque converter - the TCC is a pos and likes to fail early and often; bearing failure or stator one-way clutch failure is also somewhat common

The above assumes its actually coming from the transmission/TC and not the driveline (u-joints, pinion bearing, diff (pinion and ring gear worn on the drive side) or engine somewhere (pulley, belt, etc)...I'd not think the ring/pinion gears and/or bearings in the diff are worn out at only 103k - it'd be further down on my list of suspects.

 

[NickTransmissions]

All bearing and u-joint related problems have been ruled out by a local shop. It doesn't sound too much like it'd be an accessory drive problem considering the noise falls at mid to high rpm and is nonexistent when driving normally or cruising.

Also talked to a local transmission shop, and they are a bit perplexed as well considering the conditions the noise occurs under.

The one thing that comes to mind that would be rpm and acceleration dependent is maybe a VVT solenoid? based on the conditions that cause the noise and how VVT works, it seems plausible, but I am not a professional mechanic. I am bringing it to another mechanic I know to get him to give it a once over to see if he can pinpoint it.

Yes, please keep the thread posted...is the noise coming from the engine bay or does it sound like it's coming from underneath you?

Keep this in mind also - when you accelerate you load up the hubs and planetary carriers whereas when you coast, the load comes off. The gear train (front and rear) has a designed-in amount of longitudional travel that allows it move back/forth a little bit as its loaded up then relieved while you go on and off the gas pedal...

 

[NickTransmissions]

The location of the noise doesn't sound quite from underneath me but doesn't sound like front of the motor either. What makes it more confusing is that the noise does not occur if you are parked and rev it. Tested that to see if it was accessory drive. Kinda lends its hands to my VVT solenoid theory if VVT only occurs when the vehicle is in drive and moving.

Your second point also brings up another theory. I am trying to find a shop that has the time to change motor mounts. Having all that mass freely moving would test the tolerances a bit, so it could be that as well.

Unfortunately, I have never heard what VVT whine sounds like so can't comment...If it's only present under load (i.e. not parked or coasting while driving) then it's got to be either transmission, driveline (which sounds like you've already ruled out but prob worth having your mechanic check again to be sure while he has the vehicle) or something in the engine that's only working when under load (or where there's a state change from idle/coasting to acceleration while in gear).

Check you rear transmission mount also, assuming you haven't already and replace it if it's worn out (excessively worn rear trans mounts can actually damage the rear planet over time due to excessive vibrations on those units). Both motor and trans mounts can cause a variety of noises though bad motor mounts will also cause a sharp vibration/bumping or 'shoving' sensation when accelerating from a stop so you'd likely would have felt that if your motor mounts are bad.

Have you looked at the motor mounts and confirmed they are worn?

Do you have a mechanics stethoscope?

If so, perhaps you can poke around the engine and transmission while it's idling to see if you hear anything unusual through the scope that isn't audible with the naked ear.

 

[NickTransmissions]

I've been aware that the motor mounts and the trans mount were on their way out since I had the shop check them around 80,000 miles. Started having that bump sensation about 3,000 miles ago. They are past due, and I should've done them last month, but life has been doing what it does best in making that difficult.

I do not have a mechanic's stethoscope, but I think one of my buddies does. I might have to ask if I can borrow it.

Rgr that - yea get them changed for sure...could be them causing the noise you're hearing indirectly...if nothing else, you address a potential problem area before major problems are caused...

Same here in Vegas - heat kills so many things prematurely...everything from tires to batteries...Suspension wears faster here too due to all the off-roading we do...