Mike07LT

Hi y'all!

Intermittent issue here. My 2007 Tahoe (LT/4x4/220,000 miles) has twice now done this weird "spindown" or "whine" when I'm slowing down from speed. Sounds like it's coming from the front driveline.

The first time it happened I noticed the 4x4 actuator was engaged in 4Hi mode. I just came to a stop, put it back into 2WD and went on with my day. Yesterday we were on a 2-hour trip (each way) in the rain and I when I was slowing down from 55 at a stop light on this back country road I heard it again. It's very loud and rumbly and definitely sounds like maybe the front driveshaft is spinning freely or something. I pulled into a nearby parking lot and while the family ran into the store to get drinks and chips I put it into all transfer case modes and tranny modes. No issues. All worked flawlessly. Went on with the day and transmission seemed to shift perfectly fine...even kickdown/passing gear.

It doesn't throw any codes (except for an annoying weekly P0455 code and a new P0328 code - parts on order to fix the knock sensor code). No transmission codes and no 4WD system codes. Once in a while I DO see the "Stabilitrak Off" message in the DIC. It's also totally random and doesn't occur in tandem with this thread's main issue.

Does anyone here have a clue what this could be? If this is a transmission going out, I'm getting rid of it.

04Z71SuburbanDude

Try replacing the fluid in the transfer case and the diff. It’s very easy to do and inexpensive if you know what you’re doing. Look up Chris fixes video on replacing all fluids on YouTube. I think he even has the video split into chapters.

Mike07LT

OK I'll give that shot.

Mike07LT

Sorry for the delayed response. Finally got around to replacing the transfer case fluid. So far so good, the whine/spin down hasn’t returned. It didn’t seem low, but I went ahead and replaced it anyway.

Didn’t mention previously, but a thumping sound from the rear turned out to be the u-joint. It only was heard at low speed when there was no load on the transmission (was off the gas pedal). Dealership replaced it and no more issues there. I don’t have the right press/tools to push out the joint or I’d have done it myself and saved $200. Looks pretty simple. I really just need them to diagnose the problem.

Now that the weather is warming up, I need to get it detailed. Previous owner apparently had kids and there’s a sour milk smell starting to emanate from the rear seats/carpet 🤢. And I need to charge the AC. It cools, just not great.